Common Mistakes Mistakes that will cause a singular K matrix: -v=0.5 in a plain strain,axisymmetric or 3D solid element -E=0 in an element -Unconnected nodes -No supports,or insufficient supports -Part of the model is a mechanism -Large stiffness differencesCommon Mistakes Mistakes that will cause a singular K matrix: – ν = 0.5 in a plain strain, axisymmetric or 3D solid element – E = 0 in an element – Unconnected nodes – No supports, or insufficient supports – Part of the model is a mechanism – Large stiffness differences