6.2 Mechanics

7_DEGRADATION OF MATERIALS

Technological capacity:

• Mechanical testing laboratories with unique testing compositions constructed internally for fretting resistance tests, high-frequency resonance and axial torsion hydraulic fatigue machines, a system of electro-hydraulic load cylinders and framework loading structure. Three load testing machines (of these 1 VF, one axial-torsion with the possibility of induction heating).
• Sensors, actuators and processors for the control of mechanical tests and experimental analyses of stress and deformation. Strain gauge systems are available, as well as devices using optical fibres and FBG sensors for static and dynamic measuring, accelerometers, laser scanners, 3D image correlation cameras and high-temperature extensometers.
• Software tools for the prediction of fatigue strength and durability. The unique software tools allow for: The effective design, optimisation and evaluation of the useful life of structures under multiaxial mechanical stress and taking into account the influence of variable temperatures. Collection of existing fatigue experimental data from various sources at a large scale and their aggregation into a built-in database of experimental results.
• A number of microscopes (light metallographic, stereo, optical digital and electron) are available in the area of tools and devices for material analysis, a set of hardness testers, optical emission spectrometers and analysers. Additional software for carrying out image analysis and the evaluation of structures and phases.

8_INTERNAL DEFECTS OF AM COMPONENTS

Key equipment includes:

• A direct current potential device with a high level of parasitic effect compensation (for example changes in conductivity as a result of temperature changes, etc.) with the option to measure reference potentials in the surrounding area of the crack mouth, followed by numerical calculations of the crack length. Here the evaluation of the theoretical relationships and distribution of potentials in the cracked specimen is applied via the method of gradual iteration.
• A set of modern optical and electron microscopes with computerised image assessment. The microscopes serve primarily for subsequent checking of the numerical calibration of the crack measuring method.
• A set of SCHENCK and Amsler high-cycle fatigue tools, innovated using modern Zwick control electronics covering the whole necessary spectrum of loading forces, from the maximum capacity of 3000 N to 200 kN.
• Device for testing the fatigue life of railway axles and wheels at actual size by bending and rotation in accordance with European standards ČSN EN 13261, 13262 and associated standards. This unique next-generation device from Sincotec GmbH allows for a significant improvement in accuracy of bend loading and its uniformity over the whole circumference, which is achieved by the patented extra-massive structural framework of the machine. Part of it is a sophisticated computer-controlled regulatory system with a high number of monitoring measuring tools and regulated feedback locations.

9_CRITICAL APPLICATIONS

Technological equipment of the node:

The node is comprised of a creep laboratory with a set of more than forty creep machines (a number of them constructed internally) with the unique possibility of carrying out and comparing creep tests of materials in a regime of constant stress and load, under torsion as well as compression. Due to the internally developed furnaces with unique inserts, tests can be carried out up to temperatures of 1400°C in various atmospheres. The “small punch testing” methodology is also unique, and the node is very actively participating in its EU standardisation. The laboratory includes:

• Creep machines for helicoid samples – two machines for highly sensitive deformation experiments under low loads and two machines for medium loads.
• SATEC creep machines – eight creep machines for conventional tests of metal materials up to 1000°C in open air.
• Creep machines developed internally – a total of 35 creep machines up to 950°C, allowing for various load modes.
• Zwick/Roell creep machine – Messphysik KAPPA LA spring 20kN with a MAYTEC furnace up to 1400°C.
• Zwick/Roell test creep machine – Messphysik KAPPA LA spring 20kN, with MAYTEC furnace up to 1400°C, tests in an Ar atmosphere or vacuum.
• Zwick/Roell creep machine – Messphysik KAPPA LA spring 50kN, with a MAYTEC furnace up to 1200°C.
• Zwick/Roell test creep machine – Messphysik KAPPA LA spring 50kN, with MAYTEC furnace up to 1200 °C, tests in open air and Ar atmosphere.
• Torsion creep machine.
• A creep machine for torsion testing with high deformation sensitivity under low loads.
• ISOTECH Pegasus movable calibration furnace.

The capacities of the node also include a fatigue resistance and material durability laboratory, which offers unique experimental devices for the establishment of the fatigue characteristics and mechanical properties of materials. Key devices:

• A testing system for high-temperature tests up to 1 600°C (unique construction with internally developed inserts for extremely high temperatures similar to creep machines).
• MTS 810 servohydraulic testing machine for thermomechanical fatigue tests from room temperatures to 1000°C (a unique combination of the ability to study the behaviours material under mechanical as well as heat cycles).
• Electrodynamic testing fatigue systems with closed control loop.
• Experimental devices for multiaxial fatigue loading.
• In order to carry out extensive numerical simulations in the area of useful life prediction for industrial components, a number of powerful computer stations are available on site.

10_TRIBOLOGY

The current equipment of the node includes among other things 18 optical tribometers built internally, three universal tribometers and a 3D optical profilometer. Key equipment includes:

• The optical tribometer – unique around the world, this is an optical tribometer (laboratory device) for the measurement of ultrathin lubricating films in 15 typically different configurations, taking into account specific applications (lubricant flow in rolling bearings, vacuum conditions for aerospace applications, orientation of the rotational axes of the friction bodies, dynamic changes in speed and load on friction bodies and more), Another part are these globally unique software tools: ACHILES for the processing of interferograms and the automatic evaluation and visualisation of the thickness distribution of lubricating films in contact, ATILA for the evaluation of heat distribution both on contact surfaces and inside the lubricating film itself. Parameters: Load up to 350 N, friction surface speed up to 4 ms^-1, Hertz contact stress 3 GPa, tempering up to 150°C, sensitivity of the coefficient of friction 0.002, range of lubricating film thickness measurement up to 1500 nm, range of thermographic measurement in contact up to 300°C.
• The simulator of wheel and track contact with real geometry allows for the study of contact between friction bodies during full slip for various lubricants and friction modifiers. Also uses optical module for observation of the contact area with the possibility of assessing contact thickness and temperature distribution. Parameters: Slip speed up to 1 ms^-1, Hertz contact stress up to 0.5 GPa (UIC-ORE vs. UIC60), geometric scale 1:1.
• Twin-disc experimental device – for precise control of slippage and determination of adhesion curves. The device enables the study of the influence of various contaminants (water, lubricant, leaves, sand) on friction contact and on a laboratory scale also the ability to incline the disc. Makes use of optical modules for the observation of the contact area, using colorimetric interferometry. Parameters: Maximum rolling speed 6 ms^-1, Hertz contact stress up to 1 GPa (linear contact), geometric scale 1:12 (1:3).
• Hip and knee-joint simulator – this world-unique laboratory simulator allows for the direct observation of contact areas in grafts of the large human joints when considering changing load conditions and kinematics and taking into account actual applicable standards for implant testing. For observation of the contact area, it is possible to use colorimetric interferometry and fluorescent microscopy. Parameters: Movement frequency up to 1 Hz, load up to 3000 N, rotary flexion / extension range -20° to +60°, anterior / posterior translation range 0 to 6 mm, geometric scale 1:1.

11_TRANSPORTATION PHENOMENA

The node is based on technologies built up in atomisation and spray laboratories, aerosol laboratories and climatic chamber laboratories, built on a unique combination of experimental methods for fluid mechanics and thermomechanics. The node includes:

• Test stand for research and diagnostics of atomising devices: this is a unique machine in the Czech Republic, which can test jets to a large range of pressures (up to 16 MPa), flow rates (0-3000 l/hr), temperatures: low (up to -35°C, freeze tests) and high (up to 100°C for heavy / waste fuels) and operating substances (water, fuels, waste products, suspensions with solid particles) including complex property measurement.
• An aerodynamic tunnel for the research of dispersion systems: patented compact, segmented solution for the research of various cases of two-phase liquid-gas systems with variable flow and interaction with the surroundings.
• High-speed visualisation change – a compact, portable, autonomous unit comprised of a battery of cameras (2× high-speed (VR, Photron FASTCAM SA-Z), 3× PIV, PIV+PLIF, 2× thermal vision (VarioCAM), a set of optical elements and light sources (custom-built laser knife [Nd:YAG laser with a power output of 3 W], set of equipment for the preparation of particles to be introduced / calibrated [Safex smoke / mist generator, 2× He bubble generator Sage SAI 5]) for the recording, processing and analysis of speed, temperature and concentration fields.
• Equipment for Doppler anemometry – this combination of three compatible anemometers creates a unique set of laser diagnostic systems with large variability in settings and the ability to measure under complicated optical conditions. FDA is irreplaceable in thick sprays, flows with a broad spectrum of particle sizes, high concentrations or speeds. Parameters: diameter of particles 0.5 ÷ 2000 µm, 1D ÷ 3D speed up to 180 m/s.
• Aerosol laboratory – equipment with devices for the preparation, dispersion and measurement of solid and liquid particles from several nanometres to several tens of micrometres in size. (Condensation generation of the monodisperse aerosol TSI – CMAG 3475, particle dispersing agent TSI – SSPD 3433 with spectrometer TSI – APS 3321. Detailed measurement of nanoparticles is possible using the scanning mobility particle sizer. Among other things, the laboratory is equipped with patented models of the respiratory tract and human head replicas with plastic surfaces skin simulation (for respirator and mask tests).
• Breathing simulator – a unique device worldwide, allowing for individual setting of the breathing volume of each of the five lung lobes, chronological progression of each breath, phase delays, etc., so as to be able to simulate any kind of lung disease. Together with a patented internal lung model, it is possible to simulate the flow and settling of both medicinal and toxic particles.
• Fibre classifier – a unique fibre classifier whose main components are a result of a collaboration with Clarkson University, Potsdam, NY, USA, and which makes use of the principle of dielectrophoresis for the sorting of glass and other conductive and non-conductive materials. The only other functional device of this type worldwide is held by the Environmental Protection Agency in the USA.
• Climatic chamber – this is an entirely unique device on academic ground within Central Europe – and makes it possible to carry out experiments and developmental testing of machine products in precisely defined and repeatable climatic conditions. The internal volume of the chamber is 155 m³, temperature range -40 to +85°C, humidity 0 to 100%. Mobile solar simulator of 200 to 1100 W/m².
• Thermal manikin – shaped according to an average human body, divided into 34 zones and allowing thermal loss, convection, radiation and wiring measurements. In combination with the software developed internally, it is possible to set up the manikin to mimic the corresponding thermophysical parameters of human metabolism. The manikin is also equipped with adjustable breathing apparatus with filters. The entire system is portable and can be used not only in laboratories, but also during field measurements.

12_MACHINE DYNAMIC BEHAVIOUR

Key node instrumentation:

• Dynamic laboratory – a universal measurement space that is 18 × 12 × 6 m with defined measurement conditions (saving the measured object, environment properties, excitation of the object). The specially designed mass floor plate is isolated from the surrounding structure, including a system for anchoring the measured objects.
• The thermodynamic laboratory – a universal 12 × 12 × 6 m measurement space that is unique in the Czech Republic and has an adjustable environmental temperature at a range of +5 to +40°C. The specially designed mass floor plate is isolated from the surrounding structure, including a system for anchoring the measured objects and thermal isolation for the given temperature range. This allows for example the measurement of heat effects on machining and other tools. 
• Semi-reflective chamber – a reference laboratory space that corresponds to a free acoustic field above a reflection plane. The room is set up for measurements in the 80 Hz to 20 000 Hz range in accordance with the requirements of ISO 3745 for a maximum half-circle measurement area of 4 m. The dimensions of the space are 11.9 × 8.7 × 5.4 m. Currently, for academic and industrial partners, this is one of the largest spaces of its kind available in the Czech Republic.
• Reverberant chamber – a reference laboratory space providing a diffuse acoustic field, it is possible to precisely set the temperature and humidity of the space. The room complies with the standard ISO 354, the volume of the space is 224 m³.
• The workshop is equipped with a broad range of machinery for the static and dynamic measurement of a number of physical quantities. To begin with there are accelerometers, load cells, torque meters, sensors of displacement, angular velocity and acceleration, angle, temperature and many more quantities. Apart from the measurement of local quantities, it is also possible to record the physical field (temperature, deformation or noise). The measured signals are recorded by measuring analysers on a chronological or angular level, the current potential for measurement is 100 or more channels at simultaneously. State-of-the-art commercial or proprietary software is used for analysis.
• Apart from the standard portfolio of measurement technology, there are also unique devices such as the pair of high-speed cameras with up to 1 million fps and the option of mutual synchronisation, a thermal camera with a high dynamic range and resolution of 0.05°C including accessories for non-destructive defectoscopy, two microphone arrays (handheld rectangular and circular), a set for precise measurement of angles and angular velocity developed in-house over several generations with patented principles (up to four sensors, angular resolution of up to 0.0001°), rotating and plate dynamometers for the measurement of cutting strength and momentum from the company Kistler, making this the most comprehensive set of these sensors in the Czech Republic.