Different element types commonly used in structural Finite element Analysis (FEA).

A: The right choice captures membrane plus bending stiffness without artificial thickness locking. Tets with one element through thickness underpredict bending and spike stress, beams erase local load paths entirely, and axisymmetric elements violate the actual geometry before loads are even applied.

A: The correct answer explains why welds cracked despite low axial force. Axial overload would show up even in truss models, thermal fatigue needs a temperature driver that wasn't present, and buckling would have shown large displacement warnings long before 40,000 km.

A: The right value comes from σ = 6M/t² with consistent units. Half the value drops the factor of 2 from surface stress, double the value sneaks in a width error, and the smallest number quietly uses thickness instead of thickness squared.

A: The correct move attacks element quality where stiffness gradients live. Damping and modulus tweaks mask physics, and removing friction breaks the load path you’re trying to validate.