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1、Workbench - Mechanical Structural Nonlinearities,Chapter 4 Advanced Contact,Chapter Overview,The various advanced contact options will be discussed in detail in this chapter: These advanced options are applicable to contact involving both solid and shell body faces and edges. It is assumed that the
2、user has already covered Chapters 2 & 3 Nonlinear Structural prior to this chapter.The following will be covered in this Chapter: Body Types in Contact Auto Contact Detection Options Interface Treatments Initial Contact Conditions Workshop 4A Time Step Controls Friction Workshop 4BThe capabilities d
3、escribed in this Chapter are generally applicable to ANSYS Structural licenses and above.,Workbench Mechanical offers a rich library of Contact Technology Options: To simulate many different behaviors between faces and edges of solid and surface bodies (meshed with shell elements).,Solid Face to Sol
4、id Face,Surface Body Face to Surface body (or Solid body ) Face,Surface Body Edge to Surface Body (or Solid) Face,A. Body Types in Contact,When modeling contact between surface body faces, it is important to recognize that a surface body has a surface area, but no volume. The thickness of a surface
5、body is assigned by the user as a property in the Details window associated with the surface body When generating general frictionless or frictional contact involving surface bodies, it is necessary to identify which side (top or bottom) of the surface body is involved in the contact relationship. F
6、ailure to do this might result in contact not being recognized.,. Body Types in Contact,The Following Table identifies supported contact types, formulations and weather symmetry is respected for various contact geometries,. Body Types in Contact,B. Auto Contact Detection Options,By default, when an
7、assembly is imported from a CAD system, contact is automatically detected and contact regions are assigned for face/face conditions. These default conditions can be changed two different ways: Tool Options Dialogue Box under the Mechanical Connections Settings to change the global default behavior f
8、or multiple projects. OR Details of “Connections” Window to change behavior in an active project.,The contact default settings and automatic detection capabilities are sufficient for most contact problems. However, these additional controls are available to broaden the range of contact simulations y
9、ou can perform:,. Auto Contact Detection Options,Generate Contact on Update: Face/face contact regions are automatically created when a model is imported (updated) provided this preference is set to Yes. Setting this option to No still allows you to manually activate automatic contact generation, or
10、 construct contact regions manually. Tolerance Type, Tolerance Value, and Tolerance Slider: Bodies in an assembly that were created in a CAD system may not have been placed precisely, resulting in small overlaps or gaps along the contact regions between bodies. You can account for any imprecision by
11、 specifying contact detection tolerance (applicable to automatic contact detection only).,To tighten the contact detection between bodies, move the Tolerance Slider bar closer to +100. To loosen the contact detection, move the Tolerance Slider bar closer to -100. A tighter tolerance means that the b
12、odies have to be within a smaller region (of either gap or overlap) to be considered in contact; a loose tolerance will have the opposite effect. Contact detection tolerance can also be adjusted using an exact distance by changing the Tolerance Type to Value and entering a specific distance in the T
13、olerance Value field. A circle appears around the current cursor location as shown here.,. Auto Contact Detection Options,Existing gap between CAD parts,Graphical Illustration of user defined tolerance value for contact detection,Types of Contact Detection available between solid and surface bodies:
14、 Face/Face: contact between faces of different bodies Face/Edge: contact between faces and edges of different bodies Edge/Edge: contact between edges of different bodiesFace/Edge and Edge/Edge contact only applies to solid and surface bodies. Contact relationships involving line bodies are not suppo
15、rted. For Face/Edge detection, faces are always designated as targets and edges are always designated as contacts. You can select any combination of contacts to be detected during “Create Automatic Contact”. You can also set default preferences for these contact filter options.,. Auto Contact Detect
16、ion Options,Priority: For very large models the number of contact regions can sometimes become overwhelming and redundant, especially when multiple types of contact are allowed.,. Auto Contact Detection Options,209 parts 450 symmetric contact pairs 1.15million DOFs,Priority (contd),. Auto Contact De
17、tection Options,“Face Overrides” gives Face/Face contact precedence over both Face/Edge and Edge/Edge contact. Face Overrides also gives Face/Edge contact precedence over Edge/Edge contact. In general, when Face Overrides priority is set with Face/Edge and Edge/Edge contact, no Edge/Edge contact pai
18、rs will be detected. “Edge Overrides” gives Edge/Edge contact precedence over both Face/Edge and Face/Face contact. Edge Overrides also gives Face/Edge contact precedence over Face/Face contact. In general, when Edge Overrides priority is set with Face/Edge and Face/Face contact, no Face/Face contact pairs will be detected.,
