| Summary: | 碩士 === 國立臺灣大學 === 機械工程學系 === 85 === A new two-point approximation method for optimum design
of structures isdeveloped in this thesis. In formulation of the
optimum structural design problem, member sizes of the structure
are chosen as design variables, theweight of the structure is
considered as the objective function and differentkind of
behavior constraints, such as displacement, stresses and
naturalfrequencies, can be included in the design problem. In
the design process,a conventional two-point approximate form is
used to establish the approximateproblem. In this approximate
problem, function values and first derivatives of constraint
functions are satisfied at the current design point. Moreover,
function values of constraints at the previous design point are
also satisfied.A new method for determining the order of each
intervening variable of the approximate problem is developed
based on comparison results of design variablevalues at current
point and two latest previous points. With this newapproximation
method, optimum design of many demonstration examples in other
references can be obtained with convergent results and fewer
design interations.Finally, optimum design of a machine tool
structure and a ultra-precision XY table are carried out and
satisfactory results are obtained. It proves that this new two-
point approximation method can be used efficiently in optimum
designof large scale structures.
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