Patent ID: 7308387

Claim:
A method for simulating structural responses of a compressible material in a finite element analysis, the method comprising: defining a plurality of finite elements and a strain-stress curve to represent the compressible material; calculating a plurality of stress function f(λ) values, with each value at a particular stretch ratio λ of interest, independent of trial-and-error curve fitting determination of material constants of Ogden strain energy function, wherein each of the plurality of stress function values equals to summation of a sequence of λ 1−υj j σ 0 (λ 1−υj j ), where j is an integer related to j-th term of the sequence, ν is Poisson's ratio of the compressible material, and σ 0 (λ 1−υj j ) is the stress value at λ (−υ) j defined by the strain-stress curve for the compressible material; storing the plurality of stress function values into a lookup table; and evaluating element stresses, representing structural responses, in a local coordinate system from the lookup table in accordance with a set of principal stretches at each integration point of each of the finite elements in the finite element analysis of a structure including the compressible material.