Modeling Methods for Detailed Local Analysis

In a local detailed analysis, the flexible adhesive is modeled with three-dimensional solid elements to enable the refined capture of any local stress or strain gradients. The adhesive material is described as a rabber-like, nearly incompressible, hyperelastic material characterized by a strain energy function. Using U as the strain energy potential per unit of the reference volume, the form of the Ogden strain energy potential is shown in Eq. (1) jii and u are material parameters which are determined from adhesive material test data. 

Generally, multiple experimental test data of adhesive material are necessary for an adequate representation of the joint behavior under loading. Uniaxial tension, compression and single lap shear tests were therefore performed. 

The lap shear fatigue test for the joints of the front cab module of the Maglev Transrapid TR08 has been analyzed by a fine detail analysis with 3D solid elements using the real cross-section geometry. The adherend materials are aluminum on one side and GRP on the other see also Section 32.5.1. The PU adhesive Sikaflex -254 Booster is modeled with the Ogden strain energy equation (Eq. (1), with N=2). The computed stiffness correlates well with the test results. The local stress distribution is visualized in Fig. 32.11. 

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