In a penetration/puncture test a probe is made to penetrate into the test sample and the force necessary to achieve a certain penetration depth or the depth of penetration in a specified time, under defined conditions, is measured and used as an index of e.g. hardness, firmness, toughness.
Both test principles cause an irreversible change in the sample and assume that the sample being investigated is of larger area than the contact area of the probe in use; a sample smaller than the probe contact area would assume compression principles.
