DEVELOPMENT TRENDS AND RESULTS IN SPINAL TESTS

Spinal tests have been performed by an ultrasound-based movement test system at the Biomechanical Laboratory of the Department of Applied Mechanics of the Budapest University of Technology and Economics for several years. The system is suitable for rapid tests of the mobility, structure, and deformations of the spine, screening tests, and monitoring. Tests and evaluation take a short time: a complete screening test takes 20 to 25 minutes, a simplified test about 5 minutes. Besides its numerous advantages, it should be noted that the total cost of installing the system - equipment, software, hardware - is only about 8000 EUR. This article presents the structure and use of a modern ultrasound-based system as well as the results of our investigations

Friction of PA6 and peek composites in the light of their surface characteristics

Our present work is connected to a broad tribology research project with different polymer composites on PA6, POM, PET and PEEK matrix and targeted to create a detailed map of tribological features. Measuring the hardness and surface energy of the tribology tested materials gave some new approach about friction results. The small-scale laboratory friction tests were carried out with an alternating (reciprocating) cylinder/plate model system, which is able to measure the dynamic and the static friction force on-line during the sliding process. This special test system opens up new possibilities for understanding the phenomena of friction. In the article we give a short introduction from the surface energy and the shore D hardness test methods also. The research results plot a connection between the surface (polar and adhesion components) energy and the friction (static and dynamic) behaviour. Furthermore the experienced difference between the static and dynamic friction coefficients and its time function will offer a new approach during evaluation of the stick-slip behaviour of PA6 and PEEK composite materials

Effect Of The Different Loads Onto The Friction And Stick-Slip Of Polyamide Composites

Our present work is connected to a research project, which is based on PA6, POM, PET and PEEK polymer matrix and aimed at making a map of the features of tribology. Our work analyses the friction and connection with this, and the stick-slip behaviour of polyamide composites with different load relations. The friction tests are prepared in alternating (Reciprocating) cylinder/plane model system, developed in both the dynamic and the static friction force which is continuously measured. This special tribology test system is extremely suitable to investigate among other things the stick-slip phenomenon also. You can find detailed presentation in our earlier articles. Expected results from our research may serve in a context the effect of the different loads have on a static and dynamic friction. Our research shows the effects of friction on different levels and susceptibility of the tested materials in this direction in the stick-slip PA6 and PA66 composites

EFFECT OF THE DIFFERENT LOADS ONTO THE FRICTION AND STICK-SLIP OF POLYAMIDE COMPOSITES

Our present work is connected to a research project, which is based on PA6, POM, PET and PEEK polymer matrix and aimed at making a map of the features of tribology. Our work analyses the friction and connection with this, and the stick-slip behaviour of polyamide composites with different load relations. The friction tests are prepared in alternating (Reciprocating) cylinder/plane model system, developed in both the dynamic and the static friction force which is continuously measured. Expected results from our research may serve in a context the effect of the different loads have on a static and dynamic friction. Our research shows the effects of friction on different levels and susceptibility of the tested materials in this direction in the stick-slip PA6 and PA66 composites

Abrasive wear and abrasion testing of PA 6 and PEEK composites in small-scale model system

Abstract: Abrasion is the most common and aggressive type of wear in industrial practice. As a solution we can replace original metal components by up-to-date engineering polymer composites. However, it is not so easy to choose from the wide choice of polymers (mechanical properties, price, etc.), therefore we investigated two polymer composite groups (PA 6 and PEEK) with different mechanical properties and price. The main objective of our study was to compare the tribological properties of different PA 6 and PEEK composites, based on the results of different laboratory friction model tests. Also we wanted to investigate the effect of different additives against abrasive surface. The tests were carrying out with different load (11,5N and 23N) relations. We used emery-(grinder)-cloth to produce the abrasion mating surfaces in a special test rig. The friction tests were prepared in pin on plane (band) model system, where the friction force and the wear were continuously measured. Our present work is connected to a research project, which aims to map the tribological features of different polymer composites

A járás és a futás sebességváltozásának hatása a mozgás kinematikai és kinetikai paramétereire = Effect of the changes of the speed at walking and running to the kinematical and kinetical parameters of the motion

1./ Megfelelő mérési eljárások kidolgozása a műszerezett futópadon végrehajtott járás és futásvizsgálatok kinematikai és kinetikai paramétereinek rögzítéséhez, valamint minden egyéb szokásos és szükséges paraméter meghatározásához. 2./ Mérési protokolok kidolgozása 3./ Szoftverek kidolgozása a CMS-HS rendszer mérési adatai utófeldolgozásához járásvizsgálatok esetén: - simitó, javító és utófeldolgozó eljárások - EMG jelek kezelése, utófeldolgozása - reakcióerőmérők analóg jeleinek utófeldolgozása - Mérési eredmények szétválasztása - Anatómiai szögek meghatározása a mérési adatokból - A kinematikai adatok utófeldolgozása (deriváltak, foronómiai görbék, fázisdiagrammok stb) - A csuklóponti (izületi) igénybevételek meghatározása (inverz dinamikai feladat megoldása) - A testszegmensek szögsebességének, szöggyorsulásának meghatározása a mérési adatokból - A pillanatnyi forgástengelyek szemléltetése, a mozgások utólagos vizualizálása, stb 4./ Protokolok kidolgozása a teszteredmények megjelenítéséhez, számszerűsítés, statisztika adatfeldolgozás megoldása 5./ Szükséges mérések elvégzése, kiértékelése 6. Szoftverek tesztelése, leírások elkészitése, dokumentálása | 1./ Development of measurements methods for determening the gait and running parameters using instrumented treadmill (position of markers, anatomical points, biomechanical modell, local coordinate systems etc.) 2./ Development of protocols for measurements 3./ Software packages for postprocessing of data getted from CMS-HS system - Smoothing - EMG postprocessing (anvelope curve) - Separation of measured data - Determination of anatomical angles - Kinematical parameters (motion diagrams, derivatives, phase diagrams etc) - Solution of the inverse dynamical problem - Determination of the angular velocity of a body segment 4./ Report pages 5./ Measurements and post-processing of the measured data 6./ Tests of software packages and documentatio

Simulation of laser drilling of Inconel X-750 and Ti-5Al-2.5Sn sheets using COMSOL

This study aims to investigate the simulation of laser drilling processes on Inconel X-750 and Ti-5Al-2.5Sn sheets. To this end, COMSOL Multiphysics 5.2 software was employed to carry out the virtual experiments. A JK 701 pulsed Nd:YAG laser was used for drilling through the entire depth of Inconel X-750 and Ti-5Al-2.5Sn plates with a thickness of 2 mm and 3 mm, using laser pulses of a millisecond in time. The laser parameters varied in different combinations for well-controlled drilling through the entire thickness of the plates. Effects of laser peak power (10-20 kW) and pulse duration (0.5-2.5 ms) have been determined via studying the temperature distribution on the cross-section of the images taken in the simulation tests. Characterizing the optimum conditions obtained from the combination of parameters that improve the hole quality is an essential objective in this paper. The results suggest that the hole's diameter and depth have increased linearly as the laser beam's peak power and pulse duration are elevated. An improvement in the hole's taper ratio (the best value is 0.72) was observed as the laser beam pulse duration was longer, since an isosceles trapezoid shape was formed instead of a conical. The pulse duration exhibited more impact on the crater depth progression than the peak power. This work's outcomes might be helpful for researchers in terms of the optimum parameters proposed when studying the laser drilling of the mentioned alloys experimentally. The procedure and findings of this study are not presented elsewhere

Influence of the 3D Printing Process Settings on Tensile Strength of PLA and HT-PLA

Fused Deposition Modelling (FDM) is presently the most common utilized 3D printing technology. Since this printing technology makes the bodies anisotropic, therefore, investigate the process with different settings is worthwhile. Tensile test specimens of two plastics have been carried out to examine the mechanical properties. Polylactic acid (PLA) and High Temperature PLA (HT-PLA) are the used materials for this purpose. A total of seventy-two test pieces of the two used polymers were printed and evaluated. Three parameters were examined in twelve different settings when printing the tensile test specimens. The considered settings are; six raster directions, three build orientations and two filling factors. The differences in stress-strain curves, tensile strength values and elongation at break were compared among the tested samples. The broken specimens after the tensile test are illustrated, which gave insight into how the test pieces printed with different parameters were fractured. The optimum printing setting is represented at crossed 45/−45° raster direction, X orientation and 100 % fill factor, where the highest tensile strength of 59.7 MPa at HT-PLA and the largest elongation of about 3.5 % at PLA were measured

Tribological Behaviour Comparison of ABS Polymer Manufactured Using Turning and 3D Printing

Additive and subtractive manufacturing of Acrylonitrile Butadiene Styrene (ABS) were employed for fabricating samples. The Additive manufacturing was represented through 3D printing, whereas subtractive manufacturing carried out by Turning. Some developments have been applied for enhancing the performance of the 3D printer. Tribological measurements of the turned and 3D printed specimens have been achieved. Studying the difference between static and dynamic friction factors and the examination of wear values were included. A comparison of the tribological behaviour of the turned and 3D printed ABS polymer has been investigated

Hydrodynamic modelling and analysis of a new-developed mobile refrigerated container

In this paper the hydrodynamic air flow relations in two adjustable compartment units of the mobile refrigerated container were examined. Analytical solution of the hydrodynamic equations describing the cooling air flow motion is not possible. We applied two possible methods for the solution: (1) – small scale test, (2) – approximate solution of the ordinary differential equations with finite elements simulation. The objective of the performed tests is to define the cooling air flow kinematical conditions, such as air velocity distribution in empty and fully loaded state, testing the shape of the air inlet profile and furthermore to determine the necessity of auxiliary ventilators adaptation. According to the performed test results a proposal to the final development of the cooling and ventilation elements has been made