Morphology and function of ankylosaur dinosaur limbs are explored and analyzed using comparative morphology and finite element analysis. Reconstruction of the forelimb and posture of Pinacosaurus grangeri matches well with trackways attributed to ankylosaurs. A flexed humerus angled away from the body, perpendicular radius and ulna, and upright metacarpus forming an arch proximally result in a crescent configuration of the manus, and a semi-supinated posture relative to the main axis of the body. The ankylosaurid metatarsus has a twisted proximal articular surface, metatarsals being optimally adapted for bearing weight at increasing angles, from medial to lateral. Metatarsal counts of Thyreophorans and other basal ornithischians do not match well with currently accepted phylogeny of these taxa, indicating that a revised phylogeny should be considered. Finite element analysis results, the twisted proximal articular surface, and other morphological features support a rolling motion in the foot while pushing off in locomotion. This is perhaps an adaptation to cope with the wide hips of ankylosaurids, bringing the pes closer to the midline of the animal during locomotion to increase maneuverability. / Systematics and Evolution

Despite many research pieces on brake systems, there is still research to be done on brake pad geometry and the dissipation of heat during brake engagements using the finite element analysis method. Brake application is a process in which the kinetic energy of the vehicle is mostly converted into thermal energy and then dissipated in the form of heat. Based on dynamometer test results it was seen that brake pad temperatures could reach up to 600° C [23]. Preliminary research using computer modeling software has shown that heat dissipation in brake pads with wavy geometries and air channels from the top to bottom is much better compared to pads that do not have those specific features. Brake pads that dissipate heat faster are prone to brake fade and other braking issues that may arise due to overheating [15]. For this research, two readily available brake pads and two designs of brake pads with new geometry were modeled using CAE software. Finite element analysis was then performed to test how well each brake pad dissipated heat after reaching brake fade temperatures. The readily available brake pads were from Power Stop and Wagner [26]. ANSYS Space Claim [25] was used to design and model the brake pads, ANSYS 18.2 [24] was used to perform the finite element analysis on the pads. After performing the analysis, results indicate that a brake pad with a design that had zones for turbulent air at ambient conditions and convection slots from the top to the bottom decreased in temperature by about 90° C more in the same time compared to the conventional design. By studying the changing values of the convection heat transfer coefficient with velocity, the placing of the turbulence zones can be more precise in order attain greater airflow to remove heat from the brake pad quicker.

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Heat exchangers and steam headers are at the heart of any boiler and are susceptible to a range of failures including tube leaks, ligament cracking, creep and fatigue. These common forms of header failure mechanisms can be exacerbated by local thermal stresses due to temperature and flow maldistribution at full and partial boiler load operations. The purpose of this project is to develop process models of the outlet stubbox header of a final superheater (FSH) heat exchanger in a 620MW coal-fired drum type boiler. The process models were used to assess the impact of steam flow and temperature distribution on the thermal stresses in the header material. The process models were developed using Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). Thermocouples were installed at key locations on the stubbox headers to monitor metal temperatures and the measured metal temperatures served as boundary values and for validation of the CFD results. The thermocouple data was analysed for three different steady state boiler loads, namely full load, 80% load and 60% load. It showed that the temperature distribution across these headers was not uniform, with a maximum temperature difference across the outlet stubbox of 40℃ at full load and 43℃ at partial loads. Other relevant power plant data, such as steam pressure, was provided from the power plant's Distributed Control System (DCS) and was used as boundary conditions for the CFD models. The exact mass flow distribution across the inlet stubs of the outlet stubbox header was unknown and was estimated using a CFD model of the inlet stubbox header and steam mass flow values from power plant's DCS system. A CFD model was created for each of the three boiler loads at steady state conditions. The CFD results provided the metal temperature profile, internal steam temperature distribution and pressure distribution across the header. The CFD solid temperatures were validated using the thermocouple readings and found to be in agreement. The CFD results were exported to the FEA models, where specific displacement constraints for thermal expansion were utilised. The FEA models were used to assess the extent of thermal stresses due to thermal expansion only, as well as stresses due to thermal expansion combined with internal pressure. High local stresses were found at the borehole crotch corners of the rear outlet branch and inlet stubs. However, these are below 0.2% proof strength at elevated temperatures. The high local stresses thus did not result in local plastic deformation but contribute to exacerbate steady state failure mechanisms such as creep.

Aim of this master´s thesis is a design of tractor hook loader and stress analysis of selected parts using the fine element analysis. The theoretical part of the thesis describes general characteristics of hook loaders and summarizes critical research aimed on similar designs used by competition. Practical part deals with own design which consists of repetitive steps: design, analytical check, software simulation- if necessary, stress analysis. The last part is dedicated to drawing documentation. Assembly drawing, sub-assembly drawings and few parts drawings were composed.

Indiana University-Purdue University Indianapolis (IUPUI) / High-temperature alloys have been extensively used in many applications, such as furnace muffles, fuel nozzles, heat-treating fixtures, and fuel nozzles. Due to such conditions, these materials should have resistance to cyclic loading, oxidation, and high heat. Although there are numerous prior experimental and theoretical studies, there is insufficient understanding of application of the unified viscoplasticity theory to finite element software for fatigue life prediction. Therefore, the goal of this research is to develop a procedure to implement unified viscoplasticity theory in finite element (FE) model to model the complex material deformation pertaining to thermomechanical load and implement an incremental damage lifetime rule to predict the thermomechanical fatigue life of high-temperature alloys. The objectives of the thesis are: 1. Develop a simplified integrated approach to model the fatigue creep deformation under the framework of ‘unified viscoplasticity theory’ 2. Implement a physics - based crack growth damage model into the framework 3. Predict the deformation using the unified viscoplastic material model for ferritic cast iron (Fe-3.2C-4.0Si-0.6Mo) SiMo4.06 4. Predict the isothermal low cycle fatigue (LCF) and LCF-Creep life using the damage model In this work, a unified viscoplastic material model is applied in a FE model with a combination of Chaboche non-linear kinematic hardening, Perzyna rate model, and static recovery model to model rate-dependent plasticity, stress relaxation, and creep-fatigue interaction. Also, an incremental damage rule has been successfully implemented in a FE model. The calibrated viscoplastic model is able to correlate deformations pertaining to isothermal LCF, LCF-Creep, and thermal-mechanical fatigue (TMF) experimental deformations. The life predictions from the FE model have been fairly good at room temperature (20°C), 400°C, and 550°C under Isothermal LCF (0.00001/s and 0.003/s) and LCF-Creep tests. The material calibration techniques proposed for calibrating the model parameters resulted in a fairly good correlation of FE model derived hysteresis loops with experimental hysteresis, pertaining to Isothermal LCF (ranging from 0.00001/s to 0.003/s), Isothermal LCF-Creep tests (withhold time) and TMF responses. In summary, the method and models developed in this work are capable of simulating material deformation dependency on temperature, strain rates, hold time, therefore, they are capable of modeling creep-stress relaxation and fatigue interaction in high-temperature alloy design.

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Finite element analysis was performed on an implanted femur, using loads of daily living activities, performed by total hip replacement patients. A probabilistic bone fatigue failure model was utilized to analysis the risk of post-operative femoral fracture in different patient groups, depending on bone fatigue strength for young and elderly patients, and activity levels for normal and active patients. Different bone-implant interface conditions were considered: after surgery, osseointegrated, fibrous tissue covering, and loose. For young patients, the probability of failure is less than 4% for all cases. While in elderly patients, high of 28.2% and 57.9% are reported for normal and active groups respectively. For both age groups and activity levels, loose stems had the highest probability of failure, while osseointegrated had the lowest.

No description available.