Keywords: Single lap joint Double cantilever beam End notch flexure Adhesive bond Parameter interaction Composite Computer experiments Fracture Kriging analysis Latin hypercube sampling Toughness Strength Sensitivity a b s t r a c tThe influence of adhesive parameters on the outcome of cohesive zone finite element simulations is reported. The simulations are of adhesively bonded joint configurations that are used to characterize joint performance (including the double cantilever beam, the end notch flexure, and the single lap joint). The coupon level experiments are often used individually to determine a single parameter in an adhesive constitutive model (such as a cohesive strength or toughness). In this study, the influence of strength, toughness, and other parameters are considered simultaneously in examining their effect on the finite element (FE) output for each test. In specifying input parameters, the assumed shape of the cohesive traction law is also considered. It is shown that the double cantilever beam model output is dependent primarily on one parameter, whereas the end notch flexure and single lap joint models are dependent on multiple adhesive parameters. By extension, these dependencies require consideration when mapping the results of physical experiments into a set of adhesive model inputs. It is also shown that the shape of the traction law appears insignificant to the outcome of the models. Sensitivities to input parameters are illuminated through kriging analysis of the finite element results; the parameter values are chosen via Latin hypercube sampling. Surrogate models are created and are used to quantify the sensitivities. A mapping technique is described for evaluating the output of physical tests.

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Micro-Raman spectroscopy has been widely used to measure local stresses in silicon and other cubic materials. However, a single (scalar) line position measurement cannot determine the complete stress state unless it has a very simple form such as uniaxial. Previously published micro-Raman strategies designed to determine additional elements of the stress tensor take advantage of the polarization and intensity of the Raman-scattered light, but these strategies have not been validated experimentally. In this work, we test one such stategy [S. Narayanan, S. Kalidindi, and L. Schadler, J. Appl. Phys. 82, 2595 (1997)] for rectangular (110)and (111)-orientated silicon wafers. The wafers are subjected to a bending stress using a custom-designed apparatus, and the state of (plane) stress is modeled with ABAQUS. The Raman shifts are calculated using previously published values for silicon phonon deformation potentials. The experimentally measured values for xx , yy , and xy at the silicon surface are in good agreement with those calculated with the ABAQUS model.

Two thermomechanical analytical models are proposed for orthotropic double lap joints, and are compared to a finite element model. The solutions, based on the principle of virtual work, differ in the complexity of the assumed stress field. The first solution is similar to Volkersen, with the addition of thermal effects. The second solution captures the peel stress as well as the traction free boundary condition at the adhesive edge. Relevant non-dimensional parameters are presented for geometric, material, and load quantities. A dimensionless load ratio is identified which dictates the shape of the stress distribution. This ratio can also be used to quickly determine the dominant loading mechanism. Dimensionless stress plots are presented for representative lap joints.

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