Constraint BC for Warpage Analysis

Introduction

In warpage analysis, proper constraints should be defined on the model. This is to ensure that there are no rigid body motions/rotations. Constraints can be applied in two ways. They are:

• Fixed Constraints
• Inertia Relief Analysis (default and preferred)

Fixed Constraints

This option allows users to define the constraints manually. The following steps make sure that minimal constraints are applied on the model.

• Click on the Fixed Constraint icon in the Tool Bar under Molding ribbon.
• Make sure the vertex entity is selected. This feature is in the vertical toolbar near the graphics area.
• Select a node on the model and constrain the x-, y- and z-direction displacement.
• Next, pick a second node and constrain the y- and z-direction displacement. Make sure that this node is along an x-axis from the first node.
• Pick a third node along the y axis from the second node and constrain the z-direction displacement. Make sure that these three nodes lie on one of the axial planes, preferably on the plane with normal same as mold opening direction.

Inertia Relief Analysis

This allows simulation of unconstrained structures. The applied loads are balanced by a set of translational and rotational accelerations. These accelerations provide body forces, distributed over the structure in such a way that the sum of total of the applied forces on the structure is zero. Please refer OptiStruct User Guide for more details on the calculations.

In warp solver settings under the export settings option, select the analysis type as inertia relief. This will automatically consider the boundary conditions for steady-state stress in the structure.