A numerical model that predicts high temperature pressure vessel rupture was developed. The finite element method of analysis was used to determine the effects that various parameters had on pressure vessel failure. The work was concerned with 500, 1000 and 33000 US gallon pressure vessels made of SA 455 steel. Experimental pressure vessel fire tests have shown that vessel rupture in a fully engulfing fire can occur in less than 30 minutes. This experimental work was used both to validate the numerical results as well as to provide important vessel temperature distribution information. Due to the fact that SA 455 steel is not meant for high temperature applications, there was little published high temperature material data. Therefore, elevated temperature tensile tests and creep rupture tests were performed to measure needed material properties. Creep and creep damage constants were calculated from SA 455 steel’s creep rupture data. The Kachanov One-State Variable technique and the MPC Omega method were the creep damage techniques chosen to predict SA 455 steel’s high temperature time-dependent behaviour. The specimens used in the mechanical testing were modeled to numerically predict the creep rupture behaviour measured in the lab. An extensive comparison between the experimental and numerical uniaxial creep rupture results revealed that both techniques could adequately predict failure times at all tested conditions; however, the MPC Omega method was generally more accurate at predicting creep failure strains. The comparison also showed that the MPC Omega method was more numerically stable than the One-State Variable technique when analyzing SA 455 steel’s creep rupture. The creep models were modified to account for multiaxial states of stress and were used to analyze the high temperature failure of pressure vessels. The various parameters considered included pressure vessel dimensions, fire type (fully engulfing or local impingement), peak wall temperature and internal pressure. The objective of these analyses was to gain a better understanding of the structural failure of pressure vessels exposed to various accidental fire conditions. The numerical results of rupture time and geometry of failure region were shown to agree with experimental fire tests. From the fully engulfing fire numerical analyses, it was shown that pressure vessels with a smaller length to diameter ratio and a larger thickness to diameter ratio were inherently safer. It was also shown that as the heated area was reduced, the failure time increased for the same internal pressure and peak wall temperature. Therefore, fully engulfing fires produced more structurally unstable conditions in pressure vessels then local fire impingements. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-07-04 10:55:32.008

The present study describes the development of an FE model of tooling during production of a transmission gear. Results of the simulation at the puck/die interface during ejection examine the behavior of friction. Machine component deflections under pressure and areas of wear/binding are also predicted. The tooling was developed and modeled in Abaqus, an FE pre- and post-processor. A metal PM (Powder Metallurgy) puck is simulated from the point at the end of compaction, and then at several positions during ejection. A test setup was designed and built. The apparatus will be used to create iron powder compacts, and experimental results will be used to evaluate future models. Experiments with the new design will enable future studies of friction at the puck/die interface. The current design is for a simple puck and an increase in part geometry complexity is proposed with preliminary design requirements. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-10-02 13:53:50.789

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Many soft food materials, including vegetable shortening, exhibit complex rheological behaviour with properties that resemble those of a solid and a liquid simultaneously. The fundamental parameters used to describe the rheological response of vegetable shortening were obtained from uniaxial compression tests, including monotonic and cyclic compression, as well as creep and stress relaxation tests. The fundamental parameters obtained from the various compression tests were then used in two mechanical models (viscoelastic and elasto-visco-plastic) to predict the compression and conical indentation response of vegetable shortening. The accuracy of the two models was studied with the help of the commercially available finite element analysis software package Abaqus. It was determined that the viscoelastic model was not suitable for the prediction of the rheological response of shortening. On the other hand, the proposed elasto-visco-plastic model predicted with reasonable accuracy the uniaxial compression and indentation experimental response of vegetable shortening.

Many soft food materials, including vegetable shortening, exhibit complex rheological behaviour with properties that resemble those of a solid and a liquid simultaneously. The fundamental parameters used to describe the rheological response of vegetable shortening were obtained from uniaxial compression tests, including monotonic and cyclic compression, as well as creep and stress relaxation tests. The fundamental parameters obtained from the various compression tests were then used in two mechanical models (viscoelastic and elasto-visco-plastic) to predict the compression and conical indentation response of vegetable shortening. The accuracy of the two models was studied with the help of the commercially available finite element analysis software package Abaqus. It was determined that the viscoelastic model was not suitable for the prediction of the rheological response of shortening. On the other hand, the proposed elasto-visco-plastic model predicted with reasonable accuracy the uniaxial compression and indentation experimental response of vegetable shortening.

The jaw musculature of Champsosaurus has been enigmatic since the taxon was first described. The extant phylogenetic bracketing method is used to determine the morphology of the jaw adductor musculature. Rotational mathematics is used to calculate the muscle forces, torques, angular accelerations, and angular velocities generated by the jaw muscles. The mechanical strength of the skulls of neochoristoderes and crocodilians are investigated using finite element analysis. Finally, the hydrodynamic performance of the skulls of neochoristoderes and crocodilians is studied. The analysis is used to compare neochoristoderes to their extant ecological analogues, crocodilians, and determine the palaeoecological implications of the results. It was found that Champsosaurus rotates the lower jaw faster, the mechanical strength was lower, and shows better hydrodynamic performance than crocodilians. The results suggest that Champsosaurus was ideally suited to prey upon small or juvenile fish, and did not overlap its niche with sympatric crocodilians. / Systematics and Evolution

Scoliosis is defined as the abnormal three dimensional curvature of the spine with 80% of all cases being idiopathic in nature. If left unchecked, this condition can cause cardio-pulmonary complications and occasionally death. Currently, the most common method of treatment of scoliosis is through mechanical bracing or in extreme cases, corrective surgery. Current treatments can be further improved with a greater understand of the growth patterns of scoliotic spines. The objective of this study is to develop a finite element spine model capable of responding to loading conditions in a similar fashion to previous finite biomechanics spine model and utilize the ‘vicious cycle’ scoliosis theory in an effort to model scoliosis growth. Using CT images of a healthy spine, a three dimensional finite element model of the L3-L4 vertebra is generated. Asymmetric loading due to compression and muscle forces can then be applied on the spine and the resultant stresses are then translated into equivalent thermal load. Using this thermal load, it is possible to cause the spine model to grow, thereby predicting the growth pattern of a spine due to asymmetric loading.

The thesis presents a Finite Element Analysis (FEA) based wear modelling algorithm devised in the course of the reported research activity. FEA is used as a tool to calculate nodal pressures at the contact region for small sliding steps. These pressures are then inputted to a customised wear calculating routine. The routine uses averaged wear coefficients (wear rates) obtained from custom designed experiments. The FEA contact geometry is modified after each sliding step to account for the contact height decay, thus determining the volume loss due to wear over usage time, thus predicting the worn geometry. Consequently, the designer gains invaluable insight into the extent of wear-caused component deformation along with the number of usage cycles lapsed prior to such deformation.

Gussets plates are used in truss structures to connect multiple members. It is for this reason that it is important that the gusset plate have adequate strength to transfer forces between members, otherwise a failure in a gusset plate can cause the entire truss structure to fail. This study will focus on a gusset plate that is believed to have been under designed on the I-35W Minneapolis bridge. Three possible sources of failure will be investigated: yielding of the gusset plate, fracture of the gusset plate, and buckling of the gusset plate. Various sources such as the plans for the truss and an interim report on its failure will be utilized to construct the model for the finite element analysis. The results obtained from the finite element analysis and the traditional analysis approach using uniform force method will be used to investigate the failure of the gusset plate.