This thesis investigates the stress inside Retroreflective Raised Pavement Markers (RRPMs) under tire-marker impact and laboratory testing scenarios. Many RRPMs have poor durability although they meet certain standards of the existing laboratory tests. It has been suspected that the current testing procedures might not be adequate to decide the field performance of RRPMs. Thus, it is necessary to evaluate the existing laboratory testing procedures and develop additional ones that could simulate the field performance of RRPMs more accurately. The tire-marker impact on rigid and flexible pavement will be investigated to identify the critical locations and magnitudes of stress inside markers during the impact. Various external factors, such as tire loading, tire speed, contact angle and contact location, might have effects on the stress inside markers during the impact and be considered as critical factors when developing a laboratory test. On the other hand, RRPMs have different profiles in terms of height, lens slope, and size etc, which affect the structure and field performance as well. The study explores the stress inside markers during the impact by varying the external factors and marker profile. In addition, the interface forces between RRPMs and pavement surface will be studied. Furthermore, the tire-marker impact simulation on rigid and flexible pavement will be compared so that specific testing procedures can be distinguished based on pavement type. Finally, the existing laboratory tests will be examined and additional tests be recommended based on the tire-marker impact analysis. The researcher found that the critical compressive stress is produced at the top edges of the markers on both types of pavement, while the patterns of critical tensile stress can be different between the two types of pavement. In addition, tire loading and contact location were determined to have effect on the stress inside the markers. Furthermore, different loading rates should be used in laboratory test based on pavement type. Finally, the researcher evaluated four laboratory tests and found that each test has its merit but none of them can test RRPMs comprehensively, so it is recommended that the four tests are used together to test RRPMs.

Aluminum bond pads on semiconductor chips play an important role in IC device reliability and yield. In the paper, the vertical tension loading transferred from the capillary is clarified as the direct driving force for bond pad metal peeling. The crack on the bonding pad is identified as the root cause of the pad peeling. It is simulated by finite element method to find the effect of driving force resulting in the crack during the ultrasonic wire bonding process. It indicated that the horizontal vibration of the capillary controlled by ultrasonic power of the bonding machine was the main factors led to the crack on the bonding pad as well as its propagation into the oxide layers in chip. The degradation of Au wire/Al bond pad has become a major bonding failure problem. It is because that the molding resin with low thermal stability (e.g. bi-phenyl epoxy resin) and the IC devices under high thermal environments were used in packaging process. For the lifetime to bond failure, the bi-phenyl epoxy molding becomes shorter than that for cresol novolac epoxy due to the corrosion reaction of Au-Al intermetallics with bromine (Br) contained in the resin compounds. It was clarified that the reactive intermetallic was Au4Al phase formed in the bond interface. In addition, by utilizing the SEM, AES, EDS and XPS techniques, it could be carried out to reveal and identify defects underneath Al layer, and the contaminated Al bond pads could cause poor intermetallic growths led to the failed or unreliable connections from the chip to the outside world.

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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No description available.

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.