Thickness effect in compression testing

[SAParker]

I am testing a plastic foam core to verify its properties in uniaxial compression. We think the material we have is too soft. The specification ISO 844 I have to use specifies a thickness of 50mm. The core I can get is only 30mm thick. Will this make a difference? If it does will it be stronger or weaker? Is it possible to compensate for any difference if significant?

 

[TGund]

Check the ASTM C 365 method for flatwise compression of foam core. I believe it states that the thickness used in the test is equal to the thickness to be used in the application.

 

[RPstress]

Thickness makes a difference. ISO 844 also allows you to use a specimen the same thickness as your application if it has face sheets.

Nominally keeping the ratio of thickness to the other specimen dimensions will result in similar strengths, but there will still be some size effects.

You need to quantify your strength requirements; this will probably dictate the specimen form.