Modeling and Experimental Assessment of Bending Characteristics of Laminated Bilayer Sheet Materials

Abstract

Many mathematical models based on the advanced theory of bending to predict bending characteristics for monolithic sheet materials are available in the literature. In this work, a similar approach is utilized to develop bending models for a bilayer laminated sheet material. The principal stresses and strains through the thickness and change in relative thickness, at specified bend curvatures, are obtained as a function of increasing curvature during bending. Additionally, three-dimensional (3D) finite element (FE) based models for bilayer laminate bending are developed to overcome simplifications of the analytical models. In order to experimentally validate the two models, a new experimental bend test-jig is developed and experiments are performed on bilayer steel–aluminum laminate for different clad to matrix thickness ratios. These experiments have enabled continuous measurements of strain along the width at the bend line and through the laminate thickness at one of the specimen edges using an online strain mapping system based on digital image correlation (DIC) method. Analytical model results indicate how the through-thickness strain distribution and relative thickness of the specimen in bending are influenced by the location and thickness of the soft clad material. The FE model and experimental results exhibit similar trends in the relative thickness change for different geometric arrangements of steel–aluminum layers. The tangential and radial stresses decrease in magnitude with increasing aluminum clad thickness ratios. The 3D FE model of laminate bending provided strain predictions across the specimen width at the bend line on the tension and compression sides that increased with increasing clad thickness ratios. Also, relative thickness data from the 3D FE model showed uniaxial and plane strain stress states at the edge and midwidth sections of the test specimen. The results from analytical and FE models and from DIC and microscopic thickness measurements indicate that thickness at the bend line increases with increasing clad thickness for the case of clad layer on the compressive side of the laminate (i.e., C-C case) and vice versa for clad layer on the tensile side (C-T).

Experimental study on bending behaviour of aluminium-copper clad sheets in V-bending process

“…Moreover, aluminium undergoes higher strain in compression when it is on the inner curve (Al/Cu setting condition) compared to it in tension when it is on the outer curve (Cu/Al setting condition). The total thickness variation depends on the thickness ratio of layers [14]. As the thickness ratio between aluminium and copper is 17/3, the total thickness change in the clad sheet is decided by the change in thickness of aluminium layer.…”

“…The results were validated with the experimental results obtained by the previous authors. Ganesh and Mukesh [14] developed a bending model for bilayer laminated sheet to determine the change in relative thickness as a function of bending curvature. The results of the model indicated that the relative thickness of the sheet after bending is influenced by the location and thickness of the softer material of the clad.…”

Loading path optimization of shaft clinching forming assembly using finite element simulation and response surface methodology

“…18,19 A corresponding FE model is shown in Figure 3, and it employed the C3D8R element type. 20 The large deformation area of the flange shaft was refined with the mesh size of 1 mm × 0.6 mm and 0.5 mm along the thickness direction. A frictionless interface mode was chosen because of using grease in the clinching process.…”