Influence of specimen thickness on the deformation and fracture behaviour of wide plates

The influence of specimen thickness on the deformation behaviour and the load bearing capacity has been investigated with large scale double edge notched tension specimens (DENT). The difference of the state of stress can be modelled by simplifications (plain strain, plain stress). Equations for the calculation of plastic limit loads taking into account the defect ratio a/W have been derived based on analytical, numerical and experimental investigations. Already existing equations may lead to unsafe prediction in special situations. The difference between plastic limit and maximum load is smaller for the thicker specimens due to higher toughness requirements. The toughness requirements have been quantified for the DENT specimens using the J-integral analysis. The requirements mainly depend on the overall dimensions (W, B), the thickness ratio (B/W) and the defect ratio (a/W).