Coke drums are vertical pressure vessels used in the delayed coking process in petroleum refineries. Significant temperature variation during the delayed coking process causes the useful life of coke drums to be shortened. In order to better understand the failure mechanisms, a experimental study of elastic/plastic mechanical properties and deformation behaviors of typical coke drum materials was performed. A new biaxial thermal-mechanical material testing system has been successfully developed. Basic characterization of mechanical properties of coke drum materials is achieved through uniaxial monotonic and cyclic loading tests. In addition, strain-rate dependence and creep of coke drum materials were further experimentally investigated. Complex thermal-mechanical cyclic tests were conducted. The experimental findings help us to understand the damage mechanisms of coke drums such as bulging. In addition, experimental data serve as benchmark data to verify the predictions of the temperature dependent elastoplastic constitutive model.

No description available.

TRIP-assisted multiphase steels exhibit an excellent balance of strength and ductility, which makes them very attractive for the automotive industry. These remarkable mechanical properties can be attributed mainly to the continuous transformation of retained austenite into martensite during straining (TRansformation Induced Plasticity). The aim of this thesis was to clarify the interaction between the hot rolling conditions, the formation of microstructure, and the resulting mechanical properties. Various rolling simulation techniques were employed to determine how the composite microstructure is formed during the various steps of multi-stage thermomechanical processing. The interaction between deformation and phase transformation is highlighted, particularly from the viewpoint of the transformation texture.

The drying sequence in the manufacturing process for paperboard involves evaporation of water, primarily from within the fibres. The vapour is then transported out of the web by pressure or concentration gradients. As the moisture transport from the paper web to the ambient is quicker than the moisture transport within the fibre network to the surfaces of the web, moisture gradients develop through the thickness of the web. This work concerns effects on the mechanics of paper drying from the variation in moisture through the relatively thin structures of paper and paperboard. Distributions of inplane residual stresses through paper materials in the unloaded state after drying are believed to be caused by the varying moisture through the thickness during drying. The distributions in general exhibit compressive stress near the board surfaces and tensile stress in the interior of the board. This may be modified after drying and is also affected by structural variation in the material between different plies of multi-ply paperboards. The stress development during drying is important because it influences the resulting material properties of the paper and because it can lead to curl, which is a quality problem. The residual stresses themselves are an error source in simulation or evaluation of the mechanical behaviour of paper. In this work, residual stress distributions in paperboard were determined experimentally, to clarify the mechanisms of residual stress build-up. An experimental method for such tests was also developed. Based on the experimental findings, the mechanics of paper drying was modelled and the stress build-up simulated. Simulation offers a way of studying how the properties of paper develop during drying of wet paper webs.

No description available.

No description available.

No description available.

Coronary heart diseases are a significant cause of death among both men and women in the industrialized world; thus finding ways to detect factors which cause coronary heart diseases is worthy challenge for researchers. Ultrasound elastography system (50MHz) for measuring mechanical properties of arteries was developed as part of this thesis. Ability to discriminate between various tissue types was demonstrated using fresh and modified porcine coronary arteries, which closely models the plaque in human atherosclerosis. Elastographic measurements agreed well with uniaxial mechanical testing over a range of compression moduli.

No description available.

The primary function of the lens capsule of the eye unfolds during the process of accommodation; wherein, tension imposed onto its equator is released, allowing the elastic capsule to mold the underlying lens nucleus and cortex into a more quasispherical morphology to change focus from distant to near objects. Given its highly mechanical nature, it is prudent to study the native lens capsule from the perspective of biomechanics for such applications as understanding the mechanism of accommodation. Further, cataract surgery introduces alterations to the geometry of the lens capsule that lead to changes in resident cell behavior from quiescent to contractile and synthetic. Though resultant changes in capsule histology are well documented little has been done to quantify the corresponding altered mechanics, which is important for elucidating related post-surgical pathologies and improving prosthetic lens design. In this study we present the first data on the in situ multiaxial mechanical behavior of the native and hyperglycemic anterior lens capsule in both the porcine and human models. From these data, native stresses in the lens capsule are calculated using a finite element analysis, and alterations in the corresponding strain field are calculated after the introduction of a continuous circular capsulorhexis, which is imposed during cataract surgery. Finally, we quantify both the altered mechanical behavior and contractile loads imposed onto the lens capsule after cataract surgery.