There exists considerable motivation to reduce vehicle weight through the adoption of lightweight materials, such as aluminum alloys, while maintaining energy absorption and component integrity under crash conditions. To this end, it is of particular interest to study the crash behaviour of lightweight tubular hydroformed structures to determine how the forming behaviour affects the axial crush response. Thus, the current research has studied the dynamic crush response of both non-hydroformed and hydroformed EN-AW 5018 and AA5754 aluminum alloy tubes using both experimental and numerical methods. Experiments were performed in which hydroforming process parameters were varied in a parametric fashion after which the crash response was measured. Experimental parameters included the tube thickness and the hydroformed corner radii of the tubes. Explicit dynamic finite element simulations of the hydroforming and crash events were carried out with particular attention to the transfer of forming history from the hydroforming simulations to the crash models. The results showed that increases in the strength of the material due to work hardening during hydroforming were beneficial in increasing energy absorption during crash. However, it was shown that thinning in the corners of the tube during hydroforming decreased the energy absorption capabilities during axial crush. Residual stresses resulting from hydroforming had little effect on the energy absorption characteristics during axial crush. The current research has shown that, in addition to capturing the forming history in the crash models, it is also important to account for effects of material non-linearity such as kinematic hardening, anisotropy, and strain-rate effects in the finite element models. A model combining a non-linear kinematic hardening model, the Johnson-Cook rate sensitive model, and the Yld2000-2d anisotropic model was developed and implemented in the finite element simulations. This combined model did not account for the effect of rotational hardening (plastic spin) due to plastic deformation. It is recommended that a combined constitutive model, such as the one described in this research, be utilized for the finite element study of materials that show sensitivity to the Bauschinger effect, strain-rate effects, and anisotropy.

This thesis focuses on the analysis of the cardiac electrical and kinematic function for heart failure patients. An expected outcome is a set of computational tools that may help a clinician in understanding, diagnosing and treating patients suffering from cardiac motion asynchrony, a specific aspect of heart failure. Understanding the inverse electro-kinematic coupling relationship is the main task of this study. With this knowledge, the widely available cardiac image sequences acquired non-invasively at clinics could be used to estimate the cardiac electrophysiology (EP) without having to perform the invasive cardiac EP mapping procedures. To this end, we use real clinical cardiac sequence and a cardiac electromechanical model to create controlled synthetic sequence so as to produce a training set in an attempt to learn the cardiac electro-kinematic relationship. Creating patient-specific database of synthetic sequences allows us to study this relationship using a machine learning approach. A first contribution of this work is a non-linear registration method applied and evaluated on cardiac sequences to estimate the cardiac motion. Second, a new approach in the generation of the synthetic but virtually realistic cardiac sequence which combines a biophysical model and clinical images is developed. Finally, we present the cardiac electrophysiological activation time estimation from medical images using a patient-specific database of synthetic image sequences.

There exists considerable motivation to reduce vehicle weight through the adoption of lightweight materials, such as aluminum alloys, while maintaining energy absorption and component integrity under crash conditions. To this end, it is of particular interest to study the crash behaviour of lightweight tubular hydroformed structures to determine how the forming behaviour affects the axial crush response. Thus, the current research has studied the dynamic crush response of both non-hydroformed and hydroformed EN-AW 5018 and AA5754 aluminum alloy tubes using both experimental and numerical methods. Experiments were performed in which hydroforming process parameters were varied in a parametric fashion after which the crash response was measured. Experimental parameters included the tube thickness and the hydroformed corner radii of the tubes. Explicit dynamic finite element simulations of the hydroforming and crash events were carried out with particular attention to the transfer of forming history from the hydroforming simulations to the crash models. The results showed that increases in the strength of the material due to work hardening during hydroforming were beneficial in increasing energy absorption during crash. However, it was shown that thinning in the corners of the tube during hydroforming decreased the energy absorption capabilities during axial crush. Residual stresses resulting from hydroforming had little effect on the energy absorption characteristics during axial crush. The current research has shown that, in addition to capturing the forming history in the crash models, it is also important to account for effects of material non-linearity such as kinematic hardening, anisotropy, and strain-rate effects in the finite element models. A model combining a non-linear kinematic hardening model, the Johnson-Cook rate sensitive model, and the Yld2000-2d anisotropic model was developed and implemented in the finite element simulations. This combined model did not account for the effect of rotational hardening (plastic spin) due to plastic deformation. It is recommended that a combined constitutive model, such as the one described in this research, be utilized for the finite element study of materials that show sensitivity to the Bauschinger effect, strain-rate effects, and anisotropy.

Der Vortrag verdeutlicht die Möglichkeiten der Mathcad-Funktionen "Minimieren" bzw. "Maximieren" durch ein komplexes Beispiel aus dem Gebiet der parallelkinematischen Robotik. Innerhalb eines technologisch geforderten Arbeitsbereiches werden durch Auswertung der Vorwärts- und Rückwärtsinformation Bewertungskriterien erfasst und anschaulich dargestellt. Durch eine geeignete Formulierung mit den "Programmier"-Werkzeugen von Mathcad kann die Bewertung in einer Funktion über den gesamten Arbeitsraum automatisiert aufgerufen werden. Diese Aufbereitung gestattet die Anwendung der "Maximieren"-Funktion auf die Arbeitseigenschaften der Maschine durch Variation der kinematischen Abmessungen. Das Ergebnis der Optimierung sind die Maße des mechanischen Führungsgetriebes.

Many bridges are damaged by collisions from over-height vehicles resulting in significant impact to the transportation network. To reduce the likelihood of impact from over-height vehicles, steel pedestals have been used as a cost-effective, efficient means to increase bridge clearance heights. However, these steel pedestals installed on more than 50 bridges in Georgia have been designed with no consideration of seismic loads and may behave in a similar fashion to high-type steel bearings. Past earthquakes have revealed the susceptibility of high-type bearings to damage, resulting in the collapse of several bridges. Although Georgia is located in a low-to-moderate region of seismicity, earthquake design loads for steel pedestals should not be ignored. In this study, the potential vulnerabilities of steel pedestals having limited strength and deformation capacity and lack of adequate connection details for anchor bolts is assessed experimentally and analytically. Full-scale reversed cyclic quasi-static experimental tests are conducted on a 40' bridge specimen rehabilitated with 19" and 33" steel pedestals to determine the modes of deformation and mechanisms that can lead to modes of failure. The inelastic force-deformation hysteretic behavior of the steel pedestals obtained from experimental test results is used to calibrate an analytical bridge model developed in OpenSees. The analytical bridge model is idealized based on a multi-span continuous bridge in Georgia that has been rehabilitated with steel pedestals. The analytical bridge model is subjected to a suite of ground motions to evaluate the performance of the steel pedestals and the overall bridge system. Recommendations are made to the Georgia Department of Transportation (GDOT) for the design and construction of steel pedestals. The results of this research are useful for Georgia and other states in low-to-moderate seismic zones considering the use of steel pedestals to elevate bridges and therefore reduce the likelihood of over-height vehicle collisions.

RHex is an autonomous hexapedal robot capable of locomotion on rough terrain. Up to now, most modelling and simulation efforts on RHex were based on the linear leg assumption. These models disregarded what might be seen as the most characteristic feature of the latest iterations of this robot: the half circular legs. This thesis focuses on developing a more realistic model for this specially shaped compliant leg and studying its effects on the kinematics and dynamics of the resulting platform. One important consequence of the half circular compliant leg is the resulting rolling motion. Due to rolling, the rest length of the leg changes and the leg-ground contact point moves. Another consequence is the varying stiffness of the legs due to the changing rest length. These effect the resulting behaviour of any platform using these legs. In the first part of the thesis we are studying the effects of the half circular leg morphology on the kinematics of RHex using a simple planar model. The rest of the studies within the scope of this thesis focuses on the effect of the half circular compliant legs on the dynamics of a single legged hopping platform with a point mass. The formulation derived in this work is successfully integrated in a readily working but rather simple model of a single legged hopping system. We replace the equations of the straight leg in this model by the equations of the half circular compliant leg. Realistic results are obtained in the simulations and these results are compared to those obtained by the simpler constant stiffness straight leg model. This more realistic leg model brings us the opportunity to further study the effects of this leg morphology, in particular the positive effects of the resulting rolling motion on platform stability.

The cut slopes at a segment between Km 25+600 and 26+000 of the Antalya-Burdur Breakaway-Korkuteli State Road to be newly constructed have slope instability problems due to the existence of highly jointed limestone. The purpose of this study is to investigate the engineering geological properties of the units exposed at three cut slopes, to assess stability of the cut slopes, and to recommend remedial measures for the problematic sections. In this respect, both field and laboratory studies have been carried out. The limestone exposed at the cut slopes are beige to gray, fine grained, fossiliferous, and highly jointed. It has two joint sets and a bedding plane as main discontinuities. The kinematic analysis indicates that planar failure is expected at Km: 25+900. Limit equilibrium analysis show that the cut slopes with bench have no slope instability problems except rockfalls which endanger the traffic safety. In this thesis it is recommended to covering the cut slope with wire mesh and fibre reinforced shotcrete

This study focuses on kinematic calibration of industrial robots. Kinematic modeling, parameter identification and optimal pose selection methods are presented. A computer simulation of the kinematic calibration is performed using generated measurements with normally distributed noise. Furthermore, kinematic calibration experiments are performed on an ABB IRB 6600 industrial robot using full pose measurements taken by a laser tracking system. The kinematic model of the robot is developed using the modified Denavit - Hartenberg convention. A nonlinear least-squares method is employed during the parameter identification stage. According to the experiment results, the initial robot positioning errors are reduced by more than 80%.

The purpose of this Paper was to examine kinematic characteristics of a mechanism according to a given its kinematic schema and the dependency of the characteristics on parameters of the mechanism; to prepare a visual material for lectures and laboratory activities intended for students of physics and technology majoring in theory of machines and mechanisms. The Paper covers a review and interdependent comparison of basic methods of kinematic analysis: graphical, graphic-analytical and analytical. It is shown that in case of ordinary mechanism it is possible to make an ordinary mathematical model of mechanisms intended for examination of kinematic characteristics. Applying Visual Basic software there was a crank-slide-block mechanism and various cam-gears were designed and examined here. There are proposals given regarding application of this program during lectures and for preparation of tasks intended for laboratory activities of students.

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