In Taiwan, a motorcycle is the most important and general transportation. It is no denying that wearing a motorcycle helmet could prevent the rider from head injuries in the accidents. However, the ventilation of helmets still has to be improved. This study aims to set several ventilation channels in the energy absorption liner. They apply the Venturi effect to increase the ventilation of helmets. But it may affect the protection performance of helmet. The purpose of this study is to estimate the protective ability of the ventilative helmet. Therefore, the various ventilative helmets are designed by the computer-aided design software SolidWorks, and simulations of the impact test of the helmet are investigated by the finite element analysis software ANSYS/LS-DYNA. In addition, the effect of using different foam material is also discussed in this study.

In the past ten years, various sewage treatment technologies have got extensive and profound studying in the field of water pollution control in Taiwan. In each unit apparatus of the sewage disposal system, a lamella separator as the sewage treatment facility, is an important link in the structure, has irreplaceable functions. This research investigated the lamella separator structure by means of the static analysis, add factors of earthquake, and typhoon. To achieve the purpose, the researcher used the computer-aided design software Solidworks to set up this structure model. After that, he used finite element analysis software, ANSYS, to analyze the structure. This research simulated in three situations. In static, earthquake, and typhoon analysis, the researcher found the stress of the original modal is over the yielding stress of materials. So, the researcher modified the support of a model to reduce the stress. Generally, the researcher hoped that this study could provide helpful references for designers¡¦ relevant studies on lamella separator structure in the future.

This research investigates the stress anslysis of a tower skirt support respectively by the earthquake and the wind pressure loading. The researcher used the computer-aided design software Solidworks to set up the tower model and he used finite element software ANSYS to analyze the structure. This study aims to analyze the safety of a tower support for different models. By the finite element analysis, this study found the largest displacement of tower, the von Mises stresses, and the safety factor for the skirt support. Among them, the butted-flared skirt support has the smallest displacement. According to the analysis result, the empty crate type design of skirt support revealed the safety factor of stress greater than two, which ensure that the equipment safety and material-savings. It is expected the study findings can provide a reference for designing or repairing a tower skirt support.

Thesis (M. Phil.)--University of Hong Kong, 1989.

Thesis--M. Phil., University of Hong Kong, 1984.

Thesis--Ph. D., University of Hong Kong, 1986.

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 68-73).

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 145-149).

A nonlinear finite element program to simulate the behavior of reinforced concrete (RC) members under the action of monotonic increasing loading has been developed. The nonlinear response of the RC members is mainly due to the nonlinear material characteristics including nonlinear biaxial stress-strain relations and cracking of concrete and yielding of steel reinforcement. A constitutive model of concrete under biaxial stress state is adopted in this thesis. In this model, concrete fails and critical cracks occur when the tensile strain of concrete exceeds the limiting tensile strain. The complete stress-strain relationship of concrete under compression and tension are employed in the study to investigate the post-peak behavior of reinforced concrete members. An elaborate cracking model has been implemented which allows concrete to crack in one or two directions. The tension stiffening effect of cracked concrete is also incorporated into this model by including a descending branch in the stress-strain curve of concrete under tension. Other nonlinear effects such as crushing of concrete in compression and yielding or strain hardening of steel reinforcement are also taken into account. A nonlinear finite element program was developed, in which the abovementioned nonlinear effects have all been included in modeling the reinforced concrete structures. The nonlinear equations of equilibrium are solved using an incremental-iterative technique performed under displacement control. The validity of the model including the confinement effect of secondary reinforcements has been examined by analyzing three reinforced concrete beams. The performance of the numerical model was assessed by comparing results with those from available experimental data. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

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