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朴商洽,朴仁圭,李龍福,南炳燦 弘益大學校 科學技術硏究所 1999 科學技術硏究論文集 Vol.10 No.1
Fabrication by welding may result in stress concentration regions in the joints and it may be caused by weld imperfections on geometrical discontinuities. Thus, fatigue strength of welded details was essential for fatigue design of welding structures. In this study, constant amplitude fatigue tests on load-carrying fillet welded specimen carried out, and fatigue strength were evaluated. Also, in this investigation an attempt is made to develop a new analytical model to predict the fatigue crack propagation life of fillet welded cruciform joints of SWS 490B steels containing lack of penetration defects with more accuracy. From the result of this study, fatigue crack growth characteristics of load-carrying fillet welded cruciform joints, containing lack of penetration defects are found to be influenced by the weld size and geometry.
Steering Wheel Core 진동해석을 통한 최적화 설계에 대한 고찰
채천우(Chunwoo Chae),박동진(Dongjin Park),홍찬호(Chanho Hong),남병찬(ByungChan Nam) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
With rapid change of automotive market, multi-function and complexity in limited shape, cost reduction and weight lightening become more and more popular topic in these days. So it is necessary to study on design optimization. Steering Wheel is one of the parts that drivers touch very often in a car and its main function is steering. Especially, steering wheel vibration and noise becomes one of important quality evaluation criterion. Steering Wheel needs to meet basic strength, resonance by low natural frequency, natural frequency that meets more than optimum level and avoids fatigue fracture. Though steering wheel weight will be increased and natural frequency will be decreased relatively, designers often add rib shape on weak part for strength reinforcement and optimum natural frequency. So those methods do not work effectively. This study focus on the method that improves both of strength and natural frequency by change of geometric moment of inertia through changing cross section shape of spoke (2~4 spoke) and keeping mass at same time.Model of steering wheel core for study was simplified and every model’s rim and base keep its own shape and changed only cross section shape of spoke. Natural frequency of steering wheel core was checked by Nastran FX that used as study solver (Mesh size: 2㎜, node qty: 390,000 ~ 430,000EA, element qty 240,000 ~ 250,000). The study was conducted at same condition of armature mass by every spoke quantity. It is possible to confirm the correlation between cross section size change and its natural frequency of steering wheel core through natural frequency study and it is also possible to apply cross section size change on stress concentrated point occurred for strength reinforcement. As result, it can be judged that cross section change in same mass works on strength reinforcement, high natural frequency and cost reduction.