Institute of Theoretical and Applied Mechanics
The Institute of Theoretical and Applied Mechanics (ITAM) is a part of The Czech Academy of Science.
ITAM works on scientific research in the field of solid phase mechanics, oriented particularly on micromechanics, biomechanics of solids, statistical dynamics of systems and media, nonlinear mechanics of systems, processes of failure of materials, mechanics of multifunctional materials, mechanics of particulate media, and computer and numerical mechanics.
The research is also concerned with the economic assessment of structures, buildings, etc. incl. proposals for new methodologies for special-purpose buildings and structures and the assessment of environmental and territorial effects, particularly in the safeguarding and evaluation of historical buildings and settlements.
Since 2000 the Institute has been supported by a grant from the European Commission as a "Centre of Excellence" responsible for the project ARCCHIP (Advanced Research Centre for the Cultural Heritage Interdisciplinary Project).
Mechanics of materials
- Fracture mechanics, computational mechanics, software development, theory of finite deformations.
- Mesomechanics, thermomechanical behavior of shape memory materials.
- Mechanics of polymer composites.
Application of high-performance materials is a trend worldwide. Nowadays these materials are used in astronautics, aeronautics, industry and medicine, and the number of applications and the fields of application continue to increase. Among the most important representatives of this group of materials are materials with shape memory. The phenomenon of shape memory can be detected in many materials, but only those materials can be practically used, where the extent of shape memory is expressive.
There are two groups of such materials: (i) binary and ternary metallic alloys, and (ii) shape memory polymers. The advantage of metallic alloys lies in the high recovery stresses they are able to exhibit (up to 300MPa), while the advantage of polymers in their high recoverable deformation (up to 400%).
Mathematical modelling of the complicated thermomechanical properties of these materials is a difficult problem. The difficulty lies in the substantial dependence of these properties on temperature and in the strong hysteresis they exhibit. Up to now mathematical modelling has usually been based on broad thermodynamic considerations followed by phenomenological assumptions. Our specific approach - aimed at metallic shape memory materials - is based on a description of heterogeneity on the atomic scale that is characteristic for metallic materials exhibiting significant shape memory.
The other important representatives of the group are polymeric composites. Studies of the rheonomic behaviour of polymer composites form the main part of research activity in the field. Attention is paid to experimental methods to define their mechanical characteristics, constitutive equations, ageing, dependence of structural and mechanical properties, and assessment of their rheonomic behaviour.
Dynamics and stochastic mechanics of systems in interaction with the environment
- Dynamics of systems.
- Reliability of structures.
- Dynamic effects of wind, seismic activity and traffic.
Basic research in the field of stochastic mechanics, focusing on the dynamics of systems of rigid and deformable bodies, stability of motion, aeroelasticity, natural and technical seismicity, reliability of structures and dynamics of structures with high-speed movable load. An inherent part of this research concerns sustainable developments in the branch of signal analysis, developments in the field of stochastic finite element method, stochastic differential equation solutions, numerical and experimental methods.
Mechanics of plate and shell structures under the action of repeated loading
Research on damage to plate and shell structures under the action of combined operational loading and an aggressive corrosion environment.
Modelling of the initiation and growth of cracks in the welds of thin-walled cylindrical shells and in thin-walled plate elements with the aim to ensure (i) their integrity under extreme conditions of exploitation, (ii) methods for increasing barriers against the degradation of bodies, and (iii) means of diagnostic of damage.
Analysis and modelling of particular and cemented materials and environments
Selection of a material model plays a key role in the numerical simulation of boundary value problems in geotechnical engineering (e.g. bearing capacity of foundations or deformations in the vicinity of deep excavations). Therefore, development and testing of constitutive models is a major research task of the Laboratory of Soil Mechanics ITAM.
Due to the complexity of the phenomena observable for various types of soils it is not possible to define a unique approach leading to a perfect model. It is always necessary to take into account specific features and ways of loading of particular geomaterials. The research at ITAM concentrates on structural phenomena and formulations in the framework of hypoplasticity. The hypoplastic approach represents a relatively new model which does not distinguish between elastic and plastic deformations. Incorporation of critical states (e.g. Kolymbas et al., 1995) enables a consistent way of describing of noncohesive soils of different densities, and simplifies the calibration of material parameters (Herle and Gudehus, 1999). The cyclic behaviour can be described by introducing a further state variable, so-called intergranular strain (Niemunis and Herle, 1997). At present, the research is focused on enhancing the model for cohesive and cemented soils. Another research direction covers implementation of the model into FEM and evaluation of its influence in simulations of boundary value problems.
The geotechnical part of the research activity involves fundamental research and developing theories of lateral pressure of multi-phase granular materials together with designs theories, especially Limit State Design. In spite of the focus on the theoretical research, the results are directly useable for implementation in codes and standards.
The concept of a new, more general "General Lateral Pressure Theory" has been elaborated and is being verified and further developed by physical and numerical experiments. Due to the originality of the conception, the new original experimental equipment, instruments and computing programmes have had to be developed. The development of very advanced concepts of computing programmes is supported. At present, the stand is being modernised, the monitoring of the pressure and movements of the arbitrarily moved wall are being digitised and adapted for computer drawings. The new stand set-up will enable arbitrarily slow and continuous movement of the retaining wall, which will be drawn, monitored and recorded by the computer, as will the contact pressures.
The two components (normal and shear vertical) of the contact pressures are monitored separately, using the Czech invention of a two-component sensor (Šmíd-Novosad). The development of a three-component pressure sensor (normal, shear vertical and moment) is near to completion.
Work on design theories concentrates on Limit State Theory connected with the upcoming implementation of European Building Codes, especially EUROCODE 7-1 "Geotechnical design". A number of analyses carried out by us and by other scientists and engineers have shown that EC 7-1 is less suitable and less effective than contemporary Czech standards.
Acceptance of EC7-1 without the changes and appendices in the National Annex would be a retrograde step. Present-day Limit State Theory does not take into account the special character of geotechnics and granular materials. Thus, the basis of Limit State Theory, i.e. definitions of the characteristic and design values, is being verified. The development of appropriate alternative design approaches has already begun.
Interdisciplinary problems of architectural heritage materials.
Research at ITAM focuses on physical properties of historic materials, particularly on properties of lime mortars (Válek J. 2000), fibre reinforced mortars and their modern substitutes (Drdácky M. et al.
2003), in-situ testing of renders, mortars and historic masonry. It also involves work on problems of compatibility of new renders with historic renders and masonry.
Biomechanics of the human musculo-skeletal system
Biomechanics is a significant interdisciplinary science that studies the mechanical principles and functions of living organisms during their movement. In spite of the successful use of total endoprosthesis of joints, there are still a number of problems connected with the artificially created co-existence and interaction between the bone tissue and the technical material of the endoprosthesis. Currently we are working on extending the selection of joint replacements that will ensure optimum function for each patient after therapy. This effort requires biomechanical research on the implant during everyday activity.
Mathematical models in biomechanics are constructed on the basis of data obtained from Computed Tomography (CT), Magnetic Image Resonance (MRI) or Ultrasound Scanning (US). Algorithms from computer graphics are applied for automatic tissue segmentation, surface reconstruction of different organs and mesh optimisation for use in the Finite Element Method (FEM). The resulting models are used in stress analysis of new types of implants of the human skeletal system (total hip replacement, finger joint replacements, etc.) and their influence over the stress state of the respective tissues.
Another area of research is the development experimental methods for assessment of the mechanical properties of human tissues, in particular of long bones, muscles and ligaments. Algorithms are developed for assessing surface deformations of small samples using an image registration method with the help of a fast CCD camera able to capture up to 25 images per second. The experimental results are applied for numerical modelling of spongy bone (material models for FEM - viscoelastic properties).
Experimental methods in material and structural mechanics
In order to understand the mechanical properties of materials, bodies and structures there is a need for theoretical models of the mechanics of solid bodies. The required data is acquired by methods of experimental mechanics. In addition to generic measurement (based on the use of traditional measurement elements like tensometers, strain gauges, etc.) various methods utilizing 2D fields of data acquired by application of various physical principles (e.g. optical pixel detectors, X-ray pixel detectors, thermography, scanning electron microscope) are widely used. These methods have manifested significant development in recent years thanks to the introduction of digital means of data recording and computer assisted data processing.
Evaluation of the properties of civil (mainly historical) structures is an additional field of research. A technique for remote data transfer using the GSM network is under development for long-term observation of the mechanical properties of structures.
Elements of large civil structures are assessed by a method based on detecting of changes in the dynamic characteristics of the studied element. The development of extremely precise gauges and the availability of computational power encourages the idea of utilizing changes in dynamic characteristics for estimating the size and location of damage in a structure. Theoretical tools for this task have been prepared for both continuum and discrete systems. This task requires an experimental approach to identify the fundamental system and to locate imperfections in the system.
Diagnostics and sustainability of historical structures, materials and sites
- Sustainability of historic materials, structures and sites
- Historic timber structures including analysis of traditional technologies
- Forensic analysis in civil engineering
For safeguarding architectural and built heritage a broader interdisciplinary research of historic materials, structures and sites has been developed in recent years. It includes development of relevant methods for diagnostics, monitoring and failure analysis of mainly timber and masonry structures as well as methods of their surveying, investigation, documentation, consolidation and conservation. The Institute takes part in formulation of strategies of scientific research in this field, on building up the necessary research infrastructure, support of application and dissemination of results by means of creating methodologies for management and safeguarding historic objects and cities. There has been also developed forensic analysis which is important for the Institute activity as an Expert Institute of the highest rank listed at the Ministry of Justice of the Czech Republic and elaborating expert opinions for courts in especially difficult cases requiring scientific approach.
Laboratory of material mechanics
The laboratory is capable of providing a wide range of analysis of mechanical properties of materials, including monitoring of materials and structures. State of the art equipment in the hands of professionals provides a large number of parameters for further use both in science and in industrial areas.
Mechanical laboratory is equipped with a loading device Criterion C45
· Determination of compressive strength , tensile , flexural
· Load cells 5 , 100, 300 kN
· Climate chamber for temperature - 129-315 ° C
· Testing of building materials (wood, stone , mortar , concrete, etc ... )
· Evaluation software TW Elite
· Camera to observe the deformation of the sample
· Extensometer to determine the deformation of the sample
· Determination of strength properties , modulus
Preparation of mortars serve to prepare mortars and samples for subsequent testing. Preparation room is equipped with basic units.
· Laboratory mixer Hobart , Robot N50 - preparation of a mixture of mortars, concretes
· Vibratory screening machine Retsch AS 200 - device for screening bulk materials
· Oven with range up to 150 ° C
· Saw Dakar MEKANO 400
· Saw Clipper TT250G
· Device to measure air content in the mortar
· Device for sampling masonry in- situ + in- situ sample preparation
· Compaction table ZSC 40 - compacting cement paste
· Hägermanns percussion table - consistency of fresh suspension
· Scales Kern DS
Thermal expansion of waste glass
Effect of grinding on chemical analyses
Coal combustion byproducts analyses
Material Fatigue Laboratory
The Material Fatigue Laboratory specializes in determining the mechanical properties of construction materials, experimental fracture mechanics and the study of material damage mechanisms under repetitive or fatigue load.
HF resonance pulse generator Rumul-Mikrotron 20 kN and Instron EMR 1603 - 100 kN, used for fatigue and cyclic tests (e.g. crankshafts, CT samples)
Charpy hammer Instron/CEAST 9050 of 50 J with instrumentation for impact tests, IZOD and fast tension
Charpy hammer WPM 300 J for impact tests with thermal imaging camera
Electro-hydraulic loading frame Instron 1343 (120 kN, tensile/compressive use) for static, cyclic and dynamic tests and electromechanical testing machine Wolpert 100 kN for static tests; Meopta hardness tester and other minor equipment (CLEM laboratory)
Climactic Wind Engineering Laboratory
Climatic Wind Tunnel
- designed as a closed circuit with controlled wind velocity and temperature conditions. It consists of climatic and aerodynamic parts. While the aerodynamic part provides well-fitted conditions to study wind effects on scaled model of prototypes, an equipment of the climatic part is suited for investigation of influences of weather including the wind, temperature, rain and heat radiation. Using the cooling/heating exchanger, cycle temperature changing of the airflow is available in the whole tunnel within the range of -10 to 30 C in relatively short time period. Integral part of the tunnel equipment consists of instruments for airflow diagnostic, data acquisition system, direct pressure surface measurement, precise thermometry and of many other types of handy accessories for instant use. Workshops for manufacturing of testing models are available in the same building.
Climatic Section – experiments related to the research in engineering problems within civil engineering, architecture, heritage care and in other fields where wind effects appear along with further factors like freeze, radiant heat or rain. The climatic section is in a rectangular cross-section of 2.5 × 3.9 m with length of 9.0 m. In this section, the wind speed ranges from 0.8 to 18 m/s (depending on the position of the vertically moveable ceiling and flow nozzle). The rain intensity together with the size of drops is regulated to simulate the effects corresponding to drizzle or heavy rain. The radiation system with four infrared lamps with total power of 8 kW, and maximal incidence of 60° to the floor, is available. The power is regulated in full extent and, if needed, just one lamp can be in operation.
Aerodynamic Section - experiments in the field of wind effects on structures, wind characteristics, local wind environments, pedestrians comfort, aero-elastic structural response, diffusion, pollutant dispersion and matter transport, wind effects on building heat losses and ventilation, wind effects on transport systems, wind power generation. The aerodynamic section consists of the converting nozzle with a honeycomb and the working part with turning table. The working part is in a rectangular cross-section area of 1.9 × 1.8 m. The total length of the working part is 11.0 m, including the turbulent generators. The simulation of the atmospheric boundary layer with demanded characteristics is based upon turbulent elements, such as spires, grids, barrier and floor roughness. The wind speed range for empty working section is 1.5 – 33 m/s.
· CTA (Constant Temperature Anemometry) – also known as thermal anemometry, for the measurement of velocity and turbulence in 1, 2 or 3-dimensional air flow.
· PIV (Particle Image Velocimetry) – a non-intrusive image based measurement technique for velocity pattern diagnostics, turbulence, microfluidics and spray distribution.
· DEWETRON – the modern data acquisition system of the simultaneous sampling provides 24-bit A/D conversion with anti-aliasing filtering and the top-notch signal conditioning. Usable for analogue and digital signal capturing with advanced post-processing tools. Can be used for individual pressure measurements using pressure transducers, combined with other dynamic measurement like potentiometers, strain-gages, etc. 32 analogue channels are available.
· Traverse System Dantec - auxiliary instrument for accurate spatial mapping of measured position in the wind flow.
· Pressure Scanner Scanivalve - mean value based pressure transducer is used for the direct pressure measurement on structural surfaces.
· Pressure transducers – direct surface pressure measurement using fast sampling transducers.
· Environmental measurement – thermo cameras, vane anemometer, thermo-anemometer, temperature probes, thermo-hygrometer, atmospheric pressure sensor.
· Five-Hole Probe Aeroprobe – used to obtain the scalar and vector properties of complicated flow fields in terms of three-dimensional velocity component.
· Flow Visualization – high volume liquid droplet seeding generator, fog generator, helium (He) bubble generator system.
· Manometer LU 200 – vertical liquid column manometer for measuring variations of pressure, depression or differential pressure of air.
· Pitot Tubes – a pressure measurement instrument used to measure air flow velocity.
Laboratory of Material Analyses I
The laboratory specializes in determining the chemical composition and physical properties of rocks and mortars. We perform measurements of moisture content, porosity and pore parameters, and chemical and mineralogical characteristics of materials using XRF; thermal analyses and wet silicate analyses; and determinations of the sorption and water transport properties of construction materials. We use standard as well as proprietary testing methods. We use proprietary instruments for in-situ measurements of surface water absorption in civil engineering structures and proprietary procedures for measuring material surface cohesion. We are currently developing equipment to measure the forces generated during the salt crystallization process.
Laboratory of Material Analyses II
Chemical laboratory
This laboratory is dedicated to sample preparation and general chemical analysis. It is equipped with instruments for milling, chemical attack, physical characterization (e.g. pH, conductivity, sieving, weighting), titration, microwave digestion, ultrasonic bath, muffle furnace for the synthesis of compounds, etc.
X-rays diffraction (Bruker D8 Advance diffractometer - Bragg-Brentano theta-theta geometry)
Applications
This is the technique of election for investigating solid samples. It’s mainly used with samples in form of powders. Typical use is execution of qualitative analysis: phase identification in polycrystalline samples, identification of minerals in geological samples, detection of polymorphs in pharmaceutical samples, the determination of impurities in a pure phase (down to 0.1 weight %).
More advanced data treatment (Rietveld method) allows also to perform powder diffraction quantitative analysis: Quantification of phases into powdered samples, like minerals in geological samples, in raw materials, in industrial ceramics, refractories, cements, mortars. The technique is suitable for the quantification of non-crystalline component (amorphous) as well.
X-ray Crystallography: investigation of the crystal structure of known and unknown phases.
Crystallite size and residual strain: the determination of mean dimension of diffraction domains (crystallites) allows for the characterisation of samples undergoing thermal or mechanical treatments.
Texture analysis: the reconstruction of the distribution of orientation of the crystallites in polycrystalline samples, allows for the reconstruction of the sample microstructure. Specific orientation of crystallites develops as a result of industrial production processes (as for many metallic parts) or by action of external or internal agents. Examples are the way in which carbonate crystals grow in molluscs shells, the way in which crystal habit develops in rocks subjected to oriented pressure (metamorphism), the way in which crystals grow within processed technical ceramic bodies or metals.
Grazing incidence: identification of phases deposited at the surface of solid samples in form of films in the range 10-200nm, and their thickness. Typical field of application are materials for electronics, functional materials.
Peculiar to the last two methods is that they are non destructive, the sample is analysed without preparation with the aid of specific sample stages.
Scanning electron microscopy (SEM FEI Quanta 450 FEG )
Although the best results are obtained with a superficial conductive coating of few nanometers (usually gold or carbon), it’s possible to characterize even non-conductive samples, avoiding any treatment. Working under low vacuum and ESEM enables charge-free imaging and analysis of non-conductive and/or hydrated specimens.
Applications
NanoCharacterization: Metals & alloys, oxidation/corrosion, fractures, failure analysis, welds, polished sections, magnetic and superconducting materials. e.g. ceramics, composites, plastics, films/coatings, geological sections, minerals, soft materials (polymers, pharmaceuticals, filters, gels, tissues, plant material), particles, porous materials, cements, fibers.
In situ NanoProcesses: hydration/dehydration; wetting behaviour/contact angle analysis; oxidation/corrosion; tensile (with heat or cooling); crystallization/phase transformation.
The EDS detector allows for investigating the chemical composition with high spatial resolution.
The EBSD detector, allows for accomplishing micro-diffraction on the specimen’s surface, thus, identify the nature of crystalline phases within the sample and perform texture analysis: the reconstruction of the distribution of orientation of the crystallites in polycrystalline samples, allows for the reconstruction of the sample microstructure. Specific orientation of crystallites develops as a result of industrial production processes (as for many metallic parts) or by action of external or internal agents. Examples are the way in which carbonate crystals grow in molluscs shells, the way in which crystal habit develops in rocks subjected to oriented pressure (metamorphism), the way in which crystals grow within processed technical ceramic bodies or metals.
Chemical analysis (ICP - OES Spectroblue)
Applications
ICP-OES is a widely used analytical technique for the determination of major and trace elements. The ICP-OES technique has been applied to the analysis of a large variety of agricultural and food materials, like trace metals in beer and wine; trace elements in biological systems.
Geological applications of ICP-OES involve determinations of major, minor and trace compositions of various rocks, soils, sediments, and related materials.
Environmental analysis, analysis of drinking and waste water, soils, sludge, plants, foods.
ICP-OES is used widely for the determination of major, minor and trace elemental constituents in metals and related materials.
Analysis of organic solutions by ICP-OES is important not only for analysing organic-based materials such as petroleum products but also for a wide variety of other applications. lubricating oils for trace metal content is one of the more popular applications for organics analysis by ICP-OES. Some other applications include determination of lead in gasoline; determination of Cu, Fe, Ni, P, Si and V in cooking oils; analysis of organophosphates for trace contaminants; and determination of major and trace elements in antifreeze.
Chemical analysis (IEC (Ion Exchange Chromatography) DIONEX)
Applications
Ion chromatography system is designed to perform analysis of specific anions and cations in liquid samples. Common applications are: qualitative and quantitative determination of water soluble salts from a wide range of solid samples, such as bricks, mortars, cements and chemical analysis of water samples.
Micro Raman spectroscopy (DXR microscope)
Applications
This spectroscopic technique allows for identification of specific compounds within a wide range of specimens, organic and inorganic. With the aid of the optical microscope the laser beam can be focused down to 0,6 µm, thus, onto very small particles. Typical applications include: identification of particulate contaminants, high-resolution depth profiling and subsurface analysis on transparent and semi opaque samples, characterization of coatings, multi-layer laminates, thin films, inclusions and subsurface defects.
Good representation of carbon and silicon molecular backbones provides great differentiation of pharmaceutical and mineral polymorphs as well as differentiation of amorphous and crystalline forms of silicon and different carbon nanomaterials.
Surface areas and subsurfaces can be investigated producing x-y area maps and x-z maps. Measurements can be accomplished through glass and plastic packaging.
Infrared spectroscopy (Nicolet iN10 microscope)
Applications
This spectroscopic technique allows for identification of specific compounds within a wide range of specimens, organic and inorganic. Measurements can be performed in transmission mode (producing a small pellet containing few mg of powder sample) or in reflection mode (in which the sample surface is simply investigated). Typical applications include: microspectroscopy with identification of compounds and contaminants inside the sample, particle analysis, study of inclusions, investigation of packaging and laminate, coatings, failure analysis. Maps with compound distribution can be produced.
Thermal Analysis (STA 504)
The method is based on the measurement of changes in mass (TG) and heat flow (DTA) simultaneously, as function of temperature. This can be accomplished in the temperature range -160 – 700°C or from room temperature to 1100°C.
Applications
Typical applications include: identification of compounds following their thermal decomposition/transformation with temperature (e.g. phases of hydration in mortars and concrete), and their quantification; determination of decomposition temperatures, glass transition temperature in polymers, calculation of specific heat capacity. Engine oil volatility measurements, filler content, flammability studies, measurement of volatiles (e.g. water, oil), oxidative stabilities, thermal stabilities, catalyst and coking studies, melting/crystallization behavior. The technique is particularly suitable for the analysis of construction, ceramic and geological materials.
POROSIMETRY
Laboratory dedicated to the investigation of the structure of porous materials , identifying physical characteristics and behavior of materials, particularly materials of historic structures.
Mercury porosimeter (Autopore IV 9500)
Characterizes a material’s porosity by applying various levels of pressure to a sample immersed in mercury.
Range: pore diameter 5nm - 360 micron
Helium pycnometry (AccuPyc II 1340)
Standard method for the determination of the so-called skeletal density (density of the material excluding voids)
Sample size of 0,01 to 350 cubic centimeters
Specific surface area (Asap 2020)
Determination of surface area, also known as BET surface area and distribution of pore size in solid materials.
SAMPLE PREPARATION
Equipped with modern intruments for cutting, grinding, polishing of samples and preparation of polished and thin sections.
MICROSCOPY
Petrographic polarizing microscope operated in transmitted and reflected light
Applications
Description of the components of the material, texture, size,shape, distribution of individual components, mineralogical composition
Videomicroscopes Hirox KH 7700 with transmitted and reflected light
Digital microscope for observation with a large depth of field when placed on a tripod or hand-held
Applications
Morphology of untreated surfaces
Petrographic analyzes of the through - polarized light
Stereo Microscope SZX -7
Microscope designed for materials science with magnification up to 120x
Physical laboratory is equipped with instruments to finding the granulometric composition of the material and dilatometer to determine the coefficient of thermal expansion.
Laser granulometer CILAS LD 1090
· Measuring range 0.04 - 500 micron in the wet state
· Measurement range 0.1 - 500 micron in the dry state
· Microcell for measuring small quantities of samples
· Evaluating software Size Expert
· Testing grained materials (soils , building materials , etc ... )
Dilatometer Linseis
· High temperature furnace - temperature range from room temperature to 1400 ° C , saturation of the samples with water
· Low-temperature oven - temperature range from - 60 ° C to 500 ° C , cooling with N2
· Evaluation software Linseis
· Determination of the coefficient of thermal expansion relative elongation, Δ L
· Fixed and bulk materials
· Evaluation software Linseis Thermal Analysis
· Testing of building materials ( mortar , concrete, wood, metals)
Nanoindentor Hysitron TL 750
· Nanomechanical test of materials
· Characterization surfactant - mechanical properties of materials on the nanoscale
· Testing creation of nano cracks
· Testing of building materials , composites, inorganic materials
· Maximum dynamic force of 5 mN
· Optical display surface of the material
Laboratory of Biomechanics
Laboratory of biomechanics supports research activities of the Department of biomechanics particularly in terms of the experimental determination of mechanical characteristics of biological materials and artificial biocompatible structures by various micro-mechanical loading procedures and radiographical methods. The Laboratory provides facilities not only for the experimental research, but also for design, commissioning and testing of innovative testing equipment and state-of-the-art evaluation procedures.
Experimental Equipment (current)
Modular uni-axial loading device for radiographical and optical measurements with loading capacity up to 10 kN (proprietary design)
Compact uni-axial loading device with loading capacity up to 10 kN and interchangeable load bearing frame manufactured either from high-strength polymer or from carbon-fiber composite suitable for both optical or radiographical measurements of deformations. Motorized loading axis with movement range of 22 mm can be equipped with different load cells according to requirements of the respective experiment.
Uni-axial loading loading device for optical and radiographical measurements with loading capacity up to 0.5 kN (proprietary design)
Compact uni-axial loading device with loading capacity 0.5 kN and plexiglass load bearing frame suitable for radiographical measurements with the possibility of optical strain determination. Motorized loading axis with movement range of 20 mm can be equipped with different load cells according to requirements of the respective experiment. The device is primarily intended for measurements of trabecular bone samples and samples of tissue scaffolds.
Loading device for radiographical measurements of four-point bending experiments suitable for investigation of quasi-brittle materials (proprietary design)
Compact loading device for four-point bending experiments with loading capacity 2x 1.25 kN (1.25 kN per single loading support) and carbon-fiber composite load-bearing frame suitable for radiographical measurements. The device is composed of two loading units capable of precise synchronized movement, encoder-based readout of position, and readout of the measured force. Maximum length of samples is up to 300 mm. Cables for control, measurement and power signals are plugged into rotary slip ring connector to achieve possibility of unlimited number of rotations of the device during tomographical measurements.
Uni-axial loading device for optical and radiographical measurements with optional bio-reactor chamber and loading capacity up to 3 kN (proprietary design)
Compact uni-axial loading device with loading capacity 3 kN and interchangeable load bearing frame manufactured either from aluminium alloy or from carbon-fiber composite suitable for both optical or radiographical measurements of deformations. Positioning of the loading axis (with 30 mm movement range) is performed using high-precision ball-screw and 4 guide ways forming linear guide assembly with 20 um movement accuracy. The device can be optionally equipped with bio-reactor chamber capable of stable fluid flow with selected temperature for simulation of in-vivo conditions. Cables for control, measurement and power signals are plugged into rotary slip ring connector to achieve possibility of unlimited number of rotations of the device during tomographical measurements.
Modular electronic system for control of experimental devices (proprietary design)
System for control of experimental devices capable of precise and reliable simultaneous control of up to 5 axes. The electronics also performs readouts of physical quantities related to the respective experiment (force, temperature, fluid flow, etc.). The system is mobile and suitable for effortless measurements at other laboratories. The system is compatible with all proprietary devices at the department.
Software for control of experimental devices - RAPO (proprietary development)
Software for control of experimental devices developed at the Department of biomechanics based on a community project LinuxCNC. RAPO software is extension of real-time linux kernel with LinuxCNC environment and enables to control developed loading devices in order to satisfy their specific needs. Core and all plugins are implemented in Python programming language, graphical user interface uses Qt5 toolkit. Main features from machine control point of view are: movement of all axis to define position, experiment force and displacement control, cyclic loading, readout and logging of physical magnitudes and their real-time plotting, etc. Integral parts of RAPO software are also routines for safety operation of loading devices: overload switch, software axes limit switch, etc.). Function configuration and interface customization for the specific loading device is easily performed using a configuration file.
Three-axis translation stage (proprietary design)
High-precision motorized three-axis translation stage for positioning of optical systems based on an assembly of three individual linear stages.
Loading device for creep tests (proprietary design)
Device based on lever mechanism for long-term tensile loading of samples at elevated temperatures with force and displacement readout and the possibility of optical strain measurement.
CCD camera with bi-telecentric zoom lens
A pair of CCD monochromatic cameras equipped with GigE interface and C-mount for attachment of machine vision lenses; bi-telecentric lens with 4 magnification levels.Zatěžovací stolice Instron 4301
Universal testing system Instron 4301
Electro-mechanical testing system for uni-axial compressive/tensile tests equipped with 1 kN or 5 kN load cell. The device can be optionally equipped with thermal chamber for testing of materials at elevated temperatures.
Anti-vibration table
LED cold-light illumination system for optical measurements
Equipment under construction
Device for optical and mechanical analysis using gradual abrading
Device for optical and mechanical analysis using gradual abrading and micro-hardness measurement. The device integrates functions of a precise grinding, a microindentation and an optic inspection and image analysis without removing a sample out of the device and loss its reference position. Combining the entire workflow enables to determine material hardness distribution in whole volume of the sample with approximately 10 um vertical resolution.
Laboratory of Neutron and X-ray Radioscopy
The Laboratory is carrying out work associated with the various international projects. These projects, with support from our laboratory, involve development of a compact uniaxial loading device suitable for experiments using radiographic methods. The device under construction also includes a chamber for loading the sample, which makes it possible to maintain stable fluid circulation at the selected temperature to simulate the natural environment for biological samples during experiments. Another device being developed is an instrument for the optical and mechanical analysis of samples examined in individual cross sections using the method of gradual abrasion (by micrometric layers) and micro-indentation. Another unique device, which is currently in the pilot testing stage, is a loading machine for four-point bending test. Its design allows it to be used in combination with radiographic methods and also with large samples (up to 300 mm in length).
Research Equipment
Equipment (existing):
Uniaxial loading device for radiographic measurements up to 10 kN (proprietary design)
Uniaxial loading device for radiographic measurements up to 0,5 kN (proprietary design)
Loading device for four-point bending test for radiographic measurements (proprietary design, patent bending)
Equipment (in development/production):
Equipment for optical and mechanical analyses using grinding (proprietary design)
Uniaxial loading device for radiographic measurements with optional chamber for biological samples up to 3 kN (proprietary design)
Laboratory of diagnostics I (Built Heritage Diagnostics)
- aims at collecting the necessary data for the identification of the causes of pathologies which affect built heritage, through the application of compatible investigation techniques.
Our diagnostic work is based on a comprehensive methodology which considers qualitative and quantitative approaches; the qualitative approach being mainly based on direct observation of the structural damage and material decay as well as historical and archaeological research, and the quantitative approach mainly on material and structural tests, monitoring and structural analysis.
Activities
The Laboratory focusses on research and consultancy work related to three thematic areas:
A - NDTs and MDTs (Non-destructive and minor destructive techniques) both laboratory and in-situ.
B - Damage documentation and evaluation tools.
C - Monitoring systems.
Research
The laboratory is involved in research activities aimed at developing new tools and techniques and improving existing one, for a more compatible and less invasive diagnostic approach to built heritage protection. These activities are mostly concentrated on:
Advanced building inspection tools (e.g. MONDIS apps)
Development and validation of prototypes for innovative in-situ measurements (e.g. moisture monitoring system)
New testing criteria and guidelines for historical materials and structures (WDR testing protocol)
Thermography, x-ray and ultrasound investigation.
Consultancy
The team provides consultancy services for the identification and diagnosis of building damages. In particular the Laboratory supports the individuation of optimal solutions by performing highly specialised in situ measurements and by implementing purposely designed monitoring strategies.
Integrated Mobile Unit
The Laboratory is actively involved in the management of the Institute’s Integrated Mobile Unit (IMU). This unit, further the instrumentation employed for conventional building inspections and diagnostic measurements, it can be also equipped with documentation tools for emergency situations allowing fast assessment of building conditions.
Laboratory of diagnostics II
Members of the laboratory are dealing with identifying the causes of material degradation and its actual extent on the ground injured or threatened buildings . Furthermore primarily analyzes the impacts of natural disasters and other threats to the building fund with particular attention to the sustainability of cultural heritage and design practices and technologies to mitigate the damage caused by these hazards . Among the natural hazards (especially floods and landslides) are included , the effects of weather factors . This section deals with the squad and methodological issues optimizing rescue operations using mobile diagnostic apparatus (including newly developed) .
Reserach Equipment
The mobile laboratory is equipped for use in the field , such as natural disasters , industrial accidents, or hard to reach spots and structures and archaeological sites. Furthermore CET operates several monitoring stations for research on the influence of climate and weather parameters on the behavior of engineering materials and historical monuments. Critical infrastructure is long-established historical database of properties of materials and their disorders. The mobile laboratory is equipped with 4 x 4 car and a rich set of diagnostic tools for the analysis of physical and mechanical properties of various materials , such as:
for the diagnosis of wooden structures (resistance microdrill Resistograph 4453 -S, equipment for testing flexural strength bore Fraktometr II , ultrasonic tomography microsecond Timer 3D – 10 channels, video VideoProbe XLGo + , including several modes for measuring dimensions , hammer in indentor Pilodyn 6J Forest , handheld mobile digital microscope G20 Advanced Pack 60x & 150x , incremental bits from three different manufacturers , tip hygrometer WHT860 , strap hygrometer - L620 ) .
for the diagnosis of concrete and masonry structures (gas permeability Torrent, microwave frequency measurement of moisture in the depths of 0-5 cm , 5-15 cm and 15-30 cm , plane- saw sampling kit for collecting small samples of masonry core (diameter 25 mm) , Schmidt hammer concrete and stone, the endoscope ) .
monitoring stations ( dataloggers for monitoring T and RH , non-contact IR-thermometer up to 1000C , monitoring of surface temperatures , universal measuring center with 9 inputs with sensors on the T , RH , pressure and tensile forces and displacements ) .
Laboratory of X-ray Tomography
Research Equipment
Advanced workstation computer X-ray tomography combines two pairs of " X-ray tube - Display " (the Dual Source CT - DSCT ) in an orthogonal arrangement , which has a two-fold acceleration of the process of collecting data for tomographic reconstruction . The workplace has a fully motorized axes for distance setting "RTG - sample - detector " . This makes it possible to change the magnification of about 1.2 times to 100 times . Given the size of the detector pixels can change the resolution CT reconstruction from 0.2 millimeters to micrometers , the size of the detector. Very stable high resolution is possible also with regard to the use of anti-vibration table, on which the whole assembly is placed , and last but not least, thanks to the installation of high precision rotary table tomography .
Another advantage is the ability to work DSCT parallel imaging an object in two spectra of X-ray radiation ( so-called dual energy radiography ) . This procedure allows you to highlight differences between the material components to the full X-ray spectrum similar to the attenuation of the radiation . If the sample consists of only two materials , these materials can be clearly distinguished. For multicomponent materials can only emphasize the differences .
Departments will also be equipped with detectors type Medipix / Timepix that allow you to set the display range in 4 -bit range. This will be the combination of two successive detectors collecting data 2x16 to get energy channels and tomographic reconstructions clearly distinguish up to 32 different materials.
This work is in DSCT completely unique , even in the world .
The main components of hardware and instrumentation:
X-ray tube XWT 160 TCHR :
· The micro- CT measurements
· The minimum spot size of 1 micron
· Maximum power on the target of 3 W
· The maximum energy 160 keV
X-ray tube XWT 240 SE:
· For high power
· Minimum 4 micron spot size
· Maximum power 280 W target
· The maximum energy of 240 keV
X-ray tube XWT 240 SE is designed for high- CT measurement and is therefore suitable for large samples or samples that strongly absorb X-rays . The diameter of the radiation beam based on the X-ray tube , the spot size is 4 µm. X-ray tube produces radiation with a maximum energy of 240 keV and its maximum power is 280 W.
X-ray tube XWT 160 TCHR is designed for micro- CT measurement and is therefore more suitable for smaller samples and those that do not absorb X-rays too strongly , because it produces less radiation of maximum energy and 160 keV. This X-ray tube operates in two modes depending on the desired application . High resolution mode provides a spot size of 1 µm , but the maximum power on the target of only 3 watts High energy mode provides a spot size of 4 µm , but the maximum power is 10 W.
Flat panel detectors
· Size 400 x 400 mm
· The matrix of pixels: 2048 x 2048
· Size of pixel: 200 x 200 µm
· Indirect signal conversion
WidePix detektor
· Size : 140 x 140 mm
· Matrix of pixels: 2560 x 2560
· Size : 55 x 55 micron
· unique in the world
ABRT rotary table - 150 -AS :
· Resolution 0.55 arcseconds
· Maximum speed of 1200 rpm
· The weight capacity of 20 kg axially
· The weight capacity of 3 kg radially
Rotary table APR - 150 - DR - 135 :
· Resolution 0.08 arcseconds
· Maximum speed 600 rpm
· The weight capacity of 45 kg axially
· The weight capacity of 32 kg radially
Solvayovy Quarry - Experimental Lime Kiln
Research
Study of historical construction materials (analyses, tests, consultations, case studies)
Research on and replication of historical construction technologies
Development and design of new mortar mixtures with a composition, quality and production process corresponding to the original historical compound
Design of repair procedures for authentic elements of historical buildings in cases where the repair is carried out in such a manner that the resulting copy is as authentic as possible
Documentation of sources of historical raw materials and technologies
Identification of the origin of raw materials for lime or building stone (marble) production
Material research (optimization of production and functional properties, setting and hardening processes)
Evaluation of production factors, functional properties and environmental impacts
Research equipment
Lime kiln
The experimental lime kiln is designed for burning lime in the traditional way using wood and burning lime mixed with fuel. Typically, the kiln is operated in single charge mode, i.e. the charge is burnt and unloaded after loading; nevertheless, in case of mixed loading, the fuel and lime charges can be added and removed through the lower hole during the burning process. The single charge production of lime amounts to approx. 500 kg (CaO). The kiln is fitted with a temperature monitoring system around the shaft perimeter and with a flue gas analytical system (CO2, CO, O2). The operation and experimental use are described in publications [1, 2, 3, 4]. The lime kiln is a functional sample for project NAKI DF11P01OVV010.
Specifications:
Maximum single charge: 1 ton of stone
Fuel consumption: 600 kg wood per 500 kg CaO
Maximum temperatures: 800-1200 °C
Burning modes:
Single-charge burning using wood (mixed hardwood/softwood)
Single-charge burning of fuel/limestone mixture (f 50-80); fuel: pressed wooden briquettes or wood-coal
Well-proven lime binders - results of project NAKI DF11P01OVV010
Traditional lime slurry (functional sample)
The functional sample consists of non-hydraulic lime binder in the form of lime slurry. Its benefits include a set of properties, which are determined by the quality of the initial raw material, burning method, extinguishing in excess water and maturing. The use of lime slurry is associated with well-proven traditional procedures, which warrant the resulting quality. Recently, new key properties and process influences have been defined, which were laboratory tested and now allow quality control of the traditionally produced product [1, 5, 6]. The ability to imitate the historical original is a both unique and economically significant feature of this model product.
Traditional naturally hydrated lime (functional sample)
As the functional sample, naturally hydrated lime binder is used. It is suitable for use in civil engineering and especially for repairing historical buildings. The naturally hydrated lime was produced experimentally using dvorecko-prokopské limestone. Its unique and, at the same time, economically significant feature is its ability to imitate the original (similar initial material). The key properties and quality of the lime binder were re-validated in the laboratory with regard to traditional production and processing technologies [1, 7].
Hot lime mortar (functional sample)
As the functional sample, hot lime mortar is used, produced by lime slaking directly in a sand/water mixture. It is characterized by the ability to closely imitate the historical original, maintaining its composition and preparation process, which is essential to the guarantee of its specific properties [1]. The hot lime mortar is prepared using a procedure which involves mixing unslaked lime with damp or wet sand. The lime slaking process may take place - depending on the method of processing - at different time intervals; what is essential is that it starts at the moment the lime is mixed with the sand. Naturally hydrated lime processed as hot mortar was used to renovate the protected cooling chamber in Salajna, see fig. 6.
Specialized maps of sources of raw materials and technologies for lime production
The Calcarius maps and databases are available on the website www.calcarius.cz/gis.
The map of historical and current sources of raw materials for lime technologies shows the documented quarries and material sources from the 12th century until the present. The main attribute of the map is the indication of dates of the utilization of mineral deposits in terms of the start of mining works, time of operation, end of mining works and when the sites were left. This information is collected from archive sources, literature, and inventory and mapping geological studies, which describe the given sources of raw materials. The accuracy and completeness of the map is dependent on the quality and accuracy of the information available; generally speaking, both parameters decrease with an increase in the distance in time from the 20th century.
The map of carbonate raw materials for lime production gives a more detailed visualization of locations based on the chemical composition, age and lithological description of the stone material. The main attribute of the map, therefore, is the ability to distinguish the quarries and sources of raw materials by the geological designation of limestone and its composition. Chemical compositions are expressed as the average of analyses presented in published or archived studies. In specific cases, the chemical composition is complemented by findings collected through proprietary sampling and individual analyses. The geological composition is described and completed based on regional knowledge. The map characterizes the purity level of the raw material using the cementation index. The accuracy and completeness of the map is dependent on the availability of information sources.
The map of lime technologies allows the visualization of the locations of historical kilns, bowls, carbs, charcoal piles and other lime facilities, starting with archaeological findings from the ancient and early medieval times up until the industrial and technical monuments of the 20th century. Apart from technological descriptions, the main attribute, again, is the dates. The information used to determine the locations and technology descriptions included information from literature and written sources, the Archaeological Database of Bohemia, historical map works, our own field findings and information from regional museums, archives and websites focused on historical and technical monuments. The descriptions of archaeological findings from Moravia were taken from published written sources.
Notice: Please contact international@erc-assoc.org if you represent this Research Institution and have identified any required additions or modifications to the above information.