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3D modeling
The geometry of plastic components is dependent on the manufacturing technique used. Blow molded, roto-molded or thermoformed parts are essentially continuous surfaces wrapped around a form where they may or may not have a uniform wall thickness. Roto-molded or blow molded parts tend to be thicker at the outside and thinner at the inside. This is because they are formed from the inside of the tool. Thermoformed part are mostly the other way around, thicker on the inside and thin on the outside. Generally shells are a good method of modeling for blow-molded parts. For conceptual modeling, use solids.
Meshing
Use mesh controls to capture adequate details. Always account for wall thickness versus typical feature size. Shells do a good job, But one may loose effects of fillets and parting lines. So be careful if that is a concern.
If excessive stain or bending is observed, which may even lead to solution failure at times, or results wont make sense in some locations. Extremely distorted elements could be causing this. The only way out of this jam is to refine mesh and try again.
Material Properties
Only three things need to be kept in mind…..
(1) know your properties
(2) know your properties
(3) know your properties.
Not only properties for a given polymer vary from manufacturer to manufacturer they vary due to changes in temperature, strain rate, orientation and a host of other things. Many plastics exhibit significant non-linear elastic response before yielding and hence be very careful about the material model you are using. Verify the source of material properties and the conditions under which they are provide to you.
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