I have created a part in Abaqus: An airfoil with polyurethane interior and carbon fibre composite exterior. I have assigned polyurethane to the part. I then created a shell skin represented by two carbon fibre composite layers of 1mm thickness each. When I run a stress simulation with a force of 100s of newtons on the airfoil surface with the shell skin on my results are much much less than expected for the stress experienced in the part (on the order of E-22Pa - the part I am working on is in metres). If I take the composite shell skin off, my results are closer to what I am looking for in terms of stress in the part. Is there a better way to make a composite outer layer over a polyurethane foam interior? I am partial to ways that do not involve making a separate part for the skin layer (i.e. preferably I do not want to have to assemble from separate interior and skin parts).

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