Applications of Finite Element Analysis in Structural Engineering
Advances in the field of computer aided engineering during the last two decades have been quite extensive and have led to considerable benefits to many engineering industries. In the building industry, use of advanced finite element tools has not only allowed the introduction of innovative and efficient building products, but also the development of accurate design methods. High performance computing facilities and advanced finite element programs are now available for research and development activities in many universities in collaboration with industries. In this paper, four examples of successful applications of advanced computer tools are presented and discussed. The structural performance of steel cladding systems, innovative hollow flange beams, plasterboard lined cold-formed steel stud walls and an innovative cold-formed steel building system was accurately simulated by finite element models and thus considerably reduced the number of time consuming and expensive large scale experiments required. Both local and overall failures of various building components were investigated. New design rules, structurally improved and optimized building products and systems, and simplified behavioural and computer models were developed. This paper presents a summary of the four detailed investigations using advanced finite element tools, and selected results.
Study on ultra-light secondary baffle for coaxial two-mirror telescope
The coaxial two-mirror telescope consists of two mirrors facing each other. Classical two-mirror arrangements are Gregorian and Cassegrain. These systems are usually applied to space telescopes and often have optical baffles to prevent stray light from entering the focal plane. The optical baffles consist of concentric rings suspended between the secondary and the primary mirror. The secondary baffle for a large two-mirror optical system is designed and analyzed in this paper. According to mission of a telescope, the structure should have high stiffness and high reliability and light weight. Compared with invar, aluminum alloy and titanium alloy, carbon fiber composite is currently the best material in terms of weight-to-strength ratio. It also has advantages of high temperature tolerance and low thermal expansion. So carbon fiber composite is chosen as material to meet requirements of the coaxial telescope. In this paper, optimization method based on finite element analysis (FEA) is used for design the secondary baffle. Minimum weight of the baffle is chosen as an objective function. Thicknesses of former tube and vanes are chosen as variables. Analysis results show that the designed secondary baffle has maximum diameter of 180mm, total length of 120mm and weighs 142g. And its fundamental frequency reaches 651Hz. Therefore the baffle has many advantages, such as ultra-light weight, high stiffness and dimensional stability, etc. The optimization method and the baffle design can be helpful to other coaxial telescopes, such as Cassegrain, Gregorian and their subdivisions.
The relation of food quantity to rumination behavior.
Preliminary work suggested that the quantity of food ingested by retarded individuals who usually ruminated following meals was related to the frequency and duration of ruminating responses. This possible relation was experimentally examined by systematically varying food quantity from regular portions to satiation levels for three retarded individuals who exhibited high levels of ruminating. A clear functional relation of food quantity to ruminating emerged, with satiation procedures producing rapid and large decreases in the relatively high frequencies and durations of ruminating characteristic of baseline food quantity conditions.