Friction contact with both external and internal environments can significantly influence its efficiency, which could cause friction instabilities, vibration, and noise. Focusing on the effects that troubles brake pad, rotor, and friction-induced NVH, the main motivation for this study is to understand its drawbacks for some extent in a braking system. By proper study on applied statistics, an experimental design is planned. The design has friction tests that are performed by scaling down real test properties used in dynamometer to scaled-down properties in a subscale tester by using scaling law of physics. The test has two different types of rubbers with different humidity conditions with respect to two different brake pads in a small-scale tester, the Universal Mechanical Tester (UMT). This friction experiment helps in determining how different rubbers impact its stiffness on the coefficient of friction and noise levels, also to evaluate which scenario has the better damping capacity. The effect on the coefficient of friction and noise levels with and without rubbers is also compared. The results are subjected to the Design of Experiments analyses test know the statistical relationship between factors affecting the process and output of that process at different controllable variables namely humidity and temperature.

A method of locating structural damage is developed and tested to aid in the evaluation of structural health. This method will help minimize the cost of structural inspection and repair by informing engineers of where damage, due a seismic event, has occurred before the removal of finishes for visual inspection. This thesis begins to answer the question “can structural damage be detected solely through analysis of experimentally measured mode shapes?” The work encompasses construction of a test structure, with three braces that can be repeatedly engaged or dis-engaged, thus allowing for testing of a variety of braced configurations. For this thesis, damage is assumed to cause a change in stiffness. Experimental testing is conducted to acquire mode shapes and frequencies for the 6 dominant modes of the test structure. Lastly, the data is analyzed to identify the configuration of braces engaged on the structure. The accuracy of the method is assessed by the number of configurations that it correctly predicts and the confidence of the predictions.

The subject of this master’s thesis is manufacturing design and production of CFRP swingarm prototype for off-road motorcycle. Theoretical part describes conventional types of swingarm, provides basic introduction to composites and manufacturing technologies. Practical part describes production steps, assembly jigs and assembly process. The last part of thesis deals with measuring stiffness properties using photogrammetry system TRITOP.

Surface fault rupture poses a serious threat to infrastructure in many seismically active regions, but knowledge about the factors which control the likelihood of surface displacement is limited. Current probabilistic frameworks rely only on fault mechanism and moment magnitude to predict the probability of rupture to the ground surface. However, recent work has shown that there may be other parameters which also deserve consideration. For example, statistical analyses have demonstrated that variation in near surface material stiffness may significantly affect the probability of surface rupture over reverse faults. In addition, numerical investigations indicate that the rupture history of native soil deposits also greatly influences the nature of rupture propagation. Given that evidence exists which suggests multiple variables are at work, this study aimed to improve our understanding of which are most critical for predicting surface fault rupture hazard. We sought to generate physical evidence concerning the impact of near surface soil stiffness, soil type, and rupture history on fault rupture propagation. A 3 meter long by 1 meter wide fault box apparatus was constructed to simulate idealized reverse fault rupture oriented at 45° beneath 60cm of soil. Relatively large dimensions were chosen so that shear wave velocity measurements could be taken directly without interference from the walls of the apparatus. Experiments were conducted on loose sand, dense sand, stiff clay, and soft clay. The same sand was used for both the dense and loose sand experiments and is identified as Monterey #2/16. The clay was a scale model mixture of San Francisco Bay Mud and consisted of kaolinite, bentonite, class C fly ash, and water. Separate batches of clay were mixed with differing final water contents for the stiff and soft clay experiments. In each case, the fault box was filled to 60 cm and rupture was driven to the surface in two phases. The first phase represented an undisturbed native soil deposit with no existing shear band. The second simulated repeat rupture along a pre-existing shear band. The results indicate that increasing material stiffness promotes rupture propagation in both sand and clay. When disturbed soil is re-ruptured, surface rupture occurred much more readily in all materials. Overall, the presence of a pre-existing shear band was shown to have the greatest impact on the likelihood of surface rupture, though both material stiffness and type were also found to have a strong influence as well. The fault box experiments support the findings from previous work as well as shed new light on which parameters are most critical for accurate surface rupture predictions.

This thesis describes the steering system parts, the most common used parts and rates their advantages and disadvantages. These findings are then transferred into the Formula Student steering system design. The thesis also presents procedures leading to determine load of steering system, which is taken into account in steering system design. The final version of steering system is analyzed of stiffness.

This work deals with the design of chassis for race car category E2 made from aluminium honeycomb sandwich, design of roll cage and conception of engine mount. In the text are FEM analysis, which are focused on torsional rigidity of chassis and strength properties of roll cage.

The Master´s thesis deals with the design of device for vehicle steering stiffness measurement. In the first part were shown the most famous design solution of steering systems and basic parameters of steering geometry. The next part of the thesis is about design of the device which is using power screw. The final part of the thesis is dedicated to analysis of the most important errors which may arise during the measurement.

The thesis deals with the front part stiffness of modern vehicles, especially for the use in the field of forensic engineering in the traffic accident analysis. During the traffic accident analysis, an inquiry into the collision between vehicles is carried out which is an integral part of determining the energy loss of the vehicle at the impact, or more precisely the deformation energy expressed in the form of Energy Equivalent Speed (EES). In case of known stiffness of given part of the vehicle and based on the depth of deformation, it is possible to calculate the deformation energy, or more precisely EES corresponding with given damage of the vehicle. In the field of forensic engineering, the values of stiffness of individual vehicle components are not known and therefore, alternative methods are used to calculate the EES, they are outlined in the research part of this dissertation. However, the current methods of EES determination have some limitations when it comes to usability, and therefore, new EES calculation for the front part of the vehicle was designed in the research. It was based on the real crash test results using real stiffness characteristics of the front part of a vehicle. The front part of the vehicle is divided into individual areas and each of these parts is characterised by its own stiffness coefficient. The designed EES calculation can thus be also used for collisions with partial overlapping, taking into account the real stiffness of the damaged part of the vehicle, which was not possible with existing methods. In the research part of this dissertation, a computer programme to calculate deformation energy and EES was processed. It works with individual stiffness characteristics in given areas where the input data are entered by the user and include the depth of permanent front part deformation in individual areas, vehicle weight, the direction of an impact force and the friction coefficient on the contact surface. Considering the fact that the vehicle stiffness is also one of the control parameters at solving collisions in the PC-Crash simulation programme, which is used in forensic engineering practice for the analysis of a collision process, a supplementary computer programme was designed. Based on the above-mentioned input data, the supplementary programme can further calculate data for collision solving in the simulation programme, namely stiffness, restitution coefficient and the vehicle damage stated in the output report of the simulation programme. Based on these data, the expert thus has the opportunity to solve the collision of two vehicles in the simulation programme with as much preciseness as if it was a real collision.

There are well over 100,000 Americans on the kidney transplant list with a median wait time of 3.6 years. However, about 17 American die each day waiting for a kidney transplant, with vascular calcification being one of the most common causes [1, 2]. One vessel that is highly susceptible to vascular calcification is the aorta leading to negative cardiovascular outcomes that are secondary to kidney disease [3]. Therefore, understanding the effects that kidney disease has on disrupting the physiology of the vasculature, and finding potential therapeutic options, are imperative to those waiting for a life-saving kidney transplant. The present study aimed to test two hypotheses: (1) Aortic calcification leads to a decrease in stress in the thoracic and abdominal aorta of a young adult mouse. (2) The attenuated aortic stress seen in aortic calcification is due to the decreased expression of smooth muscle ⍺-actin (SM⍺-Actin). To test these hypotheses, calcification was induced in the ex vivo mouse aorta, followed by histological staining for calcium deposits, immunoblots for SM⍺-Actin, and measurements of aortic stress. The results of this study support the hypotheses in that calcification impairs aortic stress and it does so by decreasing the expression of SM⍺-Actin. The present study is the first to show the effect of phosphate-induced calcification on stress and expression of SM⍺-Actin in an ex vivo mouse aorta. This study is relevant to researchers as it shows key differences between studying vascular calcification in vitro compared to ex vivo. Therefore, investigating the mechanisms of aortic calcification using an ex vivo model, may be more applicable to human patients. / 2024-05-17T00:00:00Z

Acute stretching increases postural stability in nonbalance trained individuals. J Strength Cond Res 26(11): 3095-3100, 2012-Studies into the relationship between acute stretching and maintenance of postural balance have been inconclusive. It was hypothesized that familiarization with the task and subsequent learning might be involved in the conflicting results. Therefore, this study was to designed determine if a regimen of static stretching exercises after a familiarization period would improve a person's ability to maintain a stabilometer in a neutral position and whether stretching had the same effect on individuals with extensive involvement with balancing tasks. Forty-Two college students (21 male, 21 female) and 10 surfers (all male) performed tests on a stabilometer on 2 separate days after 3 days of familiarization. Testing followed either 30 minutes of quiet sitting (nonstretched) or 30 minutes of stretching activities (stretched). Stretching exercises consisted of various assisted and unassisted static stretches of the muscles around the hip, knee, and ankle joints. Improved flexibility after the stretching exercises was demonstrated by significant (p , 0.05) 6.5 6 2.7 cm (mean 6 SD) increase in the sit and reach. Balance time for the students improved significantly by 11.4% (2.0-second increase), but the surfers had no significant change. Thus, stretching improved maintenance of balance perhaps by helping the subjects to eliminate the gross muscle contractions that caused large stabilometer displacements and to replace them with fine muscle contractions that caused little or no stabilometer displacements. However, it appears that experience doing balance tasks supplants any stretching benefit.