Dome Profile Optimization and Stress Analysis of Type IV Composite Cylinders using a CLT-based MATLAB Program and FEA Validation

Type IV composite pressure (CP) vessels composed of a plastic liner and composite layers require special design attention to the dome region. The cylindrical portion of the composite cylinder is wrapped with composite layers consisting of the 900 hoop layers and low-angle helical layers, whereas the dome surface carries helical layers only. The winding angle of the helical layers being a constant over the cylindrical portion starts to vary from the cylinder-dome junction toward the boss at the top continuously. Along with the winding angle, the composite thickness also varies continuously resulting in a maximum thickness at the top crown region. The complete analysis and layer-wise stress prediction of Type IV composite cylinders for service pressures up to 70 MPa was analyzed by the Classical Lamination theory (CLT)-based MATLAB program. The MATLAB program developed in this work for the dome initially performs the dome profile generation through the numerical integration of the dome profile differential equations involving meridional and circumferential radii. A CLT formulation is successfully adopted in this work for predicting the stresses and strains accounting for the winding angle and composite thickness variations along the dome profile. A novel approach is implemented in ANSYS for accommodating the varying winding angle and composite thickness over the dome by invoking a lookup table feature in the ANAYS ACP Workbench module. The varying winding angles and composite thickness determined through the CLT MATLAB program are linked to ANSYS through the lookup table. This ensures a seamless data transfer and improves solution accuracy