TY - JOUR
AB - The paper considers the near-tip J-integral J_{tip}, the far-field J-integral J_{far} , and the experimental J-integral J^{exp} in a material with sinusoidal variation of the Young’s modulus E. The evaluations of J_{tip} and J_{far} are based on the concept of configurational forces; J^{exp} is evaluated from the area below the load point displacement curve, as prescribed by the standard testing procedures. Analytic expressions and/or approximation formulae are derived, how J_{tip}, J_{far} and J^{exp} depend on the system parameters of the material, i.e. wavelength and amplitude of the E-variation and its phase shift with respect to the crack tip position, and the global specimen dimensions. The analyses show that J_{tip} and J_{far} exhibit a strong dependency on the phase shift, but not the experimental J-integral J^{exp}. This is the reason why the current procedures for fracture mechanics testing are not suitable to determine the true values of the fracture initiation toughness J_{i} or the crack growth resistance R of a material, if the material properties exhibit a spatial variation in the direction of crack propagation. Relations are given to estimate the possible errors.
AU - R.D. Fischer
AU - J. Predan
AU - R. Müller
AU - O. Kolednik
DA - 2014/10/11/
IS - 190
JF - International Journal of Fracture
PY - 2014
SE - 2014/09/06/
SP - 23-38
TI - On problems with the determination of the fracture resistance for materials with spatial variations of the Young’s modulus
ER -