With the Loads & Boundary Condition Tools all Boundary Conditions can be created which are required for the optimisation. It can be chosen between Displacement Constraints and Structural Loads (directly or remotely applied).
Displacement Constraints:
Different displacement constraint types can be chosen. The “clamped” constraint locks the translation in all three directions. With the “general” fixation the constrained degrees of freedom can be chosen manually and can be named individually in the name sector for a better overview.
The orientation of the constraints can be influenced directly during the creation process by adding angles to the global coordinate system. Alternatively, the constraints can refer to a prior defined Local Coordinate System.
Constraints can be applied on cells, surfaces, edges and points which automatically become a Non-Design Space. To apply a constraint to a cell, the cell has to be created beforehand. This can be done using the split tool or with a Boolean operation. What cells are, how they are created and defined is mentioned here.
Forces:
In the name sector every force can be named individually.
The orientation of the force can be changed by referring to a prior defined Local Coordinate System.
Forces can be directly or remotely applied.
Direct Application
With the direct application of a force the point of load-application will be in the centre of gravity for volumes (cells) and in the centre of surfaces for surfaces. That means that the force/moment is applied of the midpoint of the chosen volume/surface/edge.
Remote Application
With the remote application the point of load-application can be placed manually. The point of load-application can be set up by choosing significant points and entering their coordinates.
Moments:
In the name sector every moment can be named individually.
The orientation of the force can be changed by referring to a prior defined Local Coordinate System.
Moments can be applied directly to a volume/surface/edge.
With the direct application of a moment the point of application will be in the centre of gravity for volumes (cells) and in the centre of surfaces for surfaces. That means that the moment is applied of the midpoint of the chosen volume/surface/edge.
Interfaces for Forces and Moments:
All forces and moments can be applied on cells, surfaces, edges and points. Please be aware, that when a boundary condition is applied on a surface/edge/point only this will automatically be an Interface. In most cases a bigger Interface is needed, which should be created separately.
The image below shows that with Interfaces on the left the functional areas that are important for the post processing are completely available. On the right side only the surfaces were used as load/constraint application points and there is very little material so that no post processing after additive manufacturing is possible.
To apply a constraint to a cell, the cell must be created first. This can be done using the split tool or with a Boolean operation. What cells are and how they are created and defined is mentioned here.
Gravity (Acceleration):
An acceleration can be created by defining the value with several g’s or a magnitude. As the direction for the acceleration, a direction of the global coordinate can be chosen. If the acceleration doesn’t correspond with the global coordinate system, a local coordinate system can be chosen. More than one acceleration can be created per optimisation however only one acceleration per load case makes sense.
The acceleration only affects the Design Space and doesn’t need to be applied on a cell or surface!
Attention: If only an acceleration and no other load is defined in the same load case, the optimisation will get rid of the whole material iterative. The acceleration force is directly dependent on the volume of the Design Space. As the Design Space is reduced so is the acceleration force until no material is left.
Pressure Load:
Pressure loads can be applied only on surfaces. It doesn’t matter if the surface is plane or not. The Pressure magnitude is the only value which is required. The chosen surface will automatically become an Interface.
Point Mass:
Point Masses can be attached to the Design Space. By default they are connected with a compliant connector (RBE3).
A Point Mass is considered for static load cases if an acceleration / gravity is active and for Frequency Optimisations. For Frequency Optimisations the connector can also be changed to a rigid one (RBE2) with the Advanced User Settings.
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