The Myth of Softening behavior of the Cohesive Zone Model Exact derivation of yield drop behavior of wood

Van der Put, T.A.C.M.

The Myth of Softening behavior of the Cohesive Zone Model Exact derivation of yield drop behavior of wood

Title

The Myth of Softening behavior of the Cohesive Zone Model Exact derivation of yield drop behavior of wood

Author

Van der Put, T.A.C.M.

Faculty

Civil Engineering and Geosciences

Department

Structural Engineering

Date

2015-11-01

Abstract

It is shown that the postulate of strain softening of the fracture stress is based on the error to regard the nominal stress to be the actual, ultimate stress, at the actual area of the fracture plan. Strain sof-tening called yield drop is elastic unloading of the actual elastic stress at the intact, not ltimate, elas-tic loaded part of the specimen, outside the fracture zone. It appears that the Griffith theory only applies for the first yield drop until half unloading and further fracture follows from a ultimate stress criterion A small-crack merging mechanism explains precisely the “softening” called yield drop curve.

Subject

wood
timber
fracture mechanics
limit analysis
strain softening
yield drop
fictitious crack model
cohesive zone model
continuum damage mechanics
small crack merging mechanism
molecular deformation kinetics