Finite Element Analysis of Plastic Components
Finite element analysis (FEA) has become one of the most popular methods for analysis in recent times. We are seeing it being used for engineering products. However, what are the factors that affect the FEA of the plastic component. So much can go wrong with the FEA of the plastic components. Let us explore them in this article.
One of the primary reasons for the failure is due to the use of the FEA software. Earlier the software used was favoring metals; as it is very easy to predict them however, beyond the yield limit it becomes very difficult to predict. For example; if we consider the analysis of a plastic part of an aircraft then we must consider the behavior of the plastic part and its range up to the yield point which is about 2-3% of the strain.
The most fatal mistake that the FEA analyst do while analyzing the plastic parts is that they consider the load that acts on the plastic part either uniformly; or as a point load and do not consider the corresponding strain up to the yield point. In metal parts, it makes perfect sense to consider the stress that is due to the corresponding load up to the plastic limit of the metal; and not to consider strain as the strain is proportional to the stress caused and which is just 2-3% of the stress caused due to the load. This is not true for the plastic part. The strain caused due to corresponding stress in a plastic part upon loading is 30% which is much more than the 2-3% that is caused in the metal part.
Therefore we should be careful while considering the linear codes as the software is designed for better parts, and not for the plastics due to the above mentioned reason.
Practices that yield good results in FEA of a plastic component:
· To conduct material test on the plastic part before going for the FEA
· Test the plastic part in the lab first and then do the FEA by using FEA software. Then compare the results.
· Try to analyze the strain also with the stress as this will give more information of the plastic part
· Use high-quality elements
· Do not go for the published properties of the plastic material. Test the material first in the lab and try to find out the properties of the plastic part yourself.
· In materials like steel; the stress, strain, and the bending stress is similar as far as the elastic modulus is concerned and therefore understand the load direction of the part under analysis. This is not true for the plastic part. While conducting FEA of the plastic part make sure that while analyzing the bending strain you consider the material properties for the flexural strain as the tensile properties won’t help and usually we get the wrong answer.