nmcnmc
Aerospace
- Sep 25, 2014
- 2
Hello, I am modelling a step lap joint in ABAQUS CAE 6.13 in 3D using solid elements (C3D8R) with cohesive contacts between matting parts to represent a bond (preliminary simplified study). At the moment my model has 5 steps in the step lap joint configuration. I am seeing the behaviour of shear stress distribution across the entire overlap (S13).
My ply has a thickness of 0.227mm and I am modelling steps with 2 plies per step, 3 plies per step and 4 plies per step, these use othotropic material properties where the layup is done in the composites property tab.
I have one issue at the moment. When modelling the bonded 2 ply thick step specimens, I get a S13 distribution as expected with peaks showing at the ends of each step. However when doeing the exact same thing but now for 3 plies and also physically increasing the geometry step height to (0.227mm * 3). I got a worng shear stress distribution. The contour plots are showing that there are no peaks at the ends of the overlap but at the edges of the 25.4mm wide specimen?
I have tried to see why this is the case. I have then modelled a 4 ply thick step specimen and get the same incorrect result again. However if I model a 2 ply thick specimen with (0.227mm * 2) thick steps and just put in 4 plies per step in the layup process I get a shear stress distribution as expected. However it still doesn't work if I am using 3 plies??
Does anyone know what might be happening here as I am completely confused by why the contour plots change to not showing peak stress at ends of the steps to the edges of the width of the specimen. Is there something wrong with simply using cohesive contacts and using surface to surface. Note that meshing is all uniform and match between the two assembled parts.
I am happy to provide the two .inp files if it will aid in people understanding the problem.
My ply has a thickness of 0.227mm and I am modelling steps with 2 plies per step, 3 plies per step and 4 plies per step, these use othotropic material properties where the layup is done in the composites property tab.
I have one issue at the moment. When modelling the bonded 2 ply thick step specimens, I get a S13 distribution as expected with peaks showing at the ends of each step. However when doeing the exact same thing but now for 3 plies and also physically increasing the geometry step height to (0.227mm * 3). I got a worng shear stress distribution. The contour plots are showing that there are no peaks at the ends of the overlap but at the edges of the 25.4mm wide specimen?
I have tried to see why this is the case. I have then modelled a 4 ply thick step specimen and get the same incorrect result again. However if I model a 2 ply thick specimen with (0.227mm * 2) thick steps and just put in 4 plies per step in the layup process I get a shear stress distribution as expected. However it still doesn't work if I am using 3 plies??
Does anyone know what might be happening here as I am completely confused by why the contour plots change to not showing peak stress at ends of the steps to the edges of the width of the specimen. Is there something wrong with simply using cohesive contacts and using surface to surface. Note that meshing is all uniform and match between the two assembled parts.
I am happy to provide the two .inp files if it will aid in people understanding the problem.