This bibliography is comprised of approximately 1,600 reference citations related to four problem areas in the mechanics of failure in aerospace structures. The bibliography represents a search of the literature published in the period 1962-1976, the effort being largely limited to documents published in the United States. Listings are subdivided into the four problem areas: Hydrogen Embrittlement; Protective Coatings; Composite Materials; and Nondestructive Evaluation. An author index is included.

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Bibliography of information on mechanics of structural failure (hydrogen embrittlement, protective coatings, composite materials, NDE)

This paper is concerned with the possibility of influencing the effects of chemically active environments on fracture processes in some controlled and predictable manner, such that their potentially detrimental effects on mechanical reliability are minimized, and their ability to facilitate fracture is utilized when this is desirable, as in materials removal processes. Phenomena such as stress-corrosion cracking, liquid metal embrittlement and chemomechanical effects are considered as they relate to the fracture behaviour of metals, ceramics, minerals, rocks, glasses, organic crystals and polymers.

Tewksbury lecture: Control and application of environment-sensitive fracture processes

Metal Matrix Composites

Fatigue tests with axial tension loading (R= 0.1) have been performed on aluminum alloy laminates having 8 and 22 layers. The laminates were similar to those previously reported for bending fatigue, having 7075–T6 layers joined by Hysol EA9410 epoxy. Both unnotched and notched (Kt= 2.42) specimens were tested.



Fatigue lifetimes for both 8- and 22-layer laminates were significantly less than for monolithic specimens tested for comparison, the differences increasing as the maximum stress decreased. This was true for both the notched and unnotched tests and is the reverse of the trends previously found in bending. While the unexpected inferiority of laminates in tension fatigue appears to be at least partially a result of material variability, it is also evident that changing the type of loading can have unpredictable effects on the comparative fatigue performance of laminates. For both unnotched and notched laminates, different layers continued to crack at different locations, demonstrating the uncoupled nature of the fatigue process in the various layers.

Axial fatigue of adhesively-bonded laminates

: The fabrication of Alloy 300M/1010 steel metal-metal laminates in thick section by hot bonding is described and discussed. The results of the forgeability testing of the roll-bonded laminate plate and the tensile, fracture toughness, fatigue, and stress-corrosion cracking properties of the roll-bonded and roll-bonded and forged laminate material and 300M monolithic control material are reported, evaluated, and discussed. Two thick laminate billets in which eighteen layers of 300M low alloy steel separated by seventeen interleaves of 1010 mild steel have been prepared by hot roll bonding from plate and sheet stock. Cylindrical specimens machined from these billets have been forged in both open and closed dies and the laminate forgeability established. The forgeability of the laminate in the longitudinal direction, i.e., material flow perpendicular to the lamellar plane, is limited to low strains, less than -27%, by the hot strength of the interlamellar bonds and the plastic buckling resistance of the laminate. The forgeability in the transverse direction, i.e., material flow parallel to the lamellar plane, is limited only by the acceptable reorientation of laminate fiber caused by die shape and the frictional characteristics of the process, the transverse flow of the layers and interleaves being completely stable in the 300M/1010 system.

Roll-Bonded 300M/1010 Steel Metal-Metal Laminates: Forgeability, Toughness, Fatigue, and Stress Corrosion.

Laminated plate composites were prepared by hot roll bonding together plates of 18Ni(280) maraging steel and sheets of Armco iron. Composite welds of the same geometry were also prepared by successively depositing weld layers of these two materials. Plane strain stress corrosion tests of these two types of composites in aerated 3.5% NaCl solutions showed that stress corrosion crack propagation was stopped at stress intensities well above the KISCC values of the corresponding homogeneous maraging steel base plate and maraging steel weld metal. The results demonstrate that it is possible to retard stress corrosion crack propagation significantly in both base plate and weld structures by the use of a composite approach.

S. Floreen

Papers

Stress Corrosion Cracking Behavior of Maraging Steel Composites

The Fabricability and Toughness of Laminar Composites of Maraging Steel