irregularities such as non-uniform ply-thicknesses and fiber distribution, incomplete ply bonding, and random voids. Two fatigue specimens sustained 10 Kc of high level cyclic loading and had a residual strength of approximately the static value; a third specimen frac-tured on cycle 1 at 75 % of the static

The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. The use of trade name(s) and/or manufacture(s) does not constitute an official indorsement or approval. DISPOSITION Destroy this report when it is no longer needed. Do not return it to the originator.

Approval of the thesis: EFFECTS OF GEOMETRICAL FACTORS ON FRACTURE TOUGHNESS

ABSTRACT: A novel crack specimen has been designed to study brittle fracture in mode II loading. The test specimen is simulated using finite element analysis and the crack tip parameters KII and T are calculated. Both tensile and compressive loading can be applied to the specimen. For tensile

ABSTRACT: The size effect on quasi-brittle fracture is modelled by considering the distance of crack-tip to specimen boundary. It is shown that the tensile strength criterion applies if specimen boundary is very close to the crack-tip, and the fracture toughness criterion applies if specimen

of the specimen bulk material. The degradation of the interlaminar connection can be taken into account by means either of an appropriate damage initiation criterion and damage evolu-tion law or using fracture mechanics approach. Onset and growth of the delami-nation pre-existing crack in the fracture specimens

The fracture behavior of the main layers used in food packaging material is studied. Investigations include aluminium foil (9µm), paper board (100 µm) and Low Density Polyethylene (27 µm). The plane stress fracture toughness of each layer is derived based on a centered crack panel. Different crack

Abstract not found

of separated concrete segments and cracks are collected and analyzed. Under increasing load, the concrete specimen can undergo size distortion. The largest segments and cracks account for 99 % of the change. Some segments and cracks merge. 1.

ABSTRACT: A unified approach is proposed to evaluate the compliance and energy release rate (ERR) of generic beam-type interface fracture specimens. Based on a sub-layer Timoshenko beam theory, the classic composite (rigid joint), shear deform-able (semi-rigid joint), and interface deformable