Axial Fatigue of Adhesively-Bonded Laminates

A B S T R A C TThe results of fatigue and crack propagation tests carried out on dog-bone specimens made of 2024-T3 are described. Two types of specimens were investigated: the first was machined from a 1.27-mm-thick sheet, while the second was machined from a bonded metal-laminated sheet, made of four 0.3-mm-thick layers. Crack propagation tests confirmed the high resistance of metal-laminated sheets to the propagation of fatigue cracks, compared to monolithic sheets, once again. At the same time, standard fatigue tests, carried out up to the final failure of the specimens, demonstrated a comparable fatigue resistance of monolithic and laminated specimens. As a consequence, it can be concluded that fatigue cracks nucleated earlier in the metal-laminated specimens, compared to the monolithic ones, but propagated more slowly. This behaviour was attributed to the presence of sharp edges in the inner laminas of metal-laminated materials which cannot be eliminated by deburring. Additional tests were carried out on monolithic specimens containing burrs and sharp edges at the holes. These specimens were drilled and reamed after stacking and pressing them to form a package. The specimens were fatigue tested without deburring the holes. A decrease in the fatigue resistance was observed. The formation of burrs and sharp edges was additionally promoted by inserting plastic foils between the specimens during the machining operations. Fatigue resistance of these specimens is progressively lower.

Section: Introductionmentioning

confidence: 99%

Fatigue properties of monolithic and metal‐laminated aluminium open‐hole specimens

Lanciotti

Polese

2008

“…Crack initiation plays a dominant r61e in the fatigue behaviour of 7075-epoxy laminates described by Alic [7]. For lifetimes in the range 104-106 cycles the laminates exhibit poorer fatigue properties than monolithic 7075, and the difference is most marked at low stress amplitudes and in unnotched specimens (see Figs 3 and 4 of ref.…”

Section: Crack Initiationmentioning

confidence: 99%

“…For lifetimes in the range 104-106 cycles the laminates exhibit poorer fatigue properties than monolithic 7075, and the difference is most marked at low stress amplitudes and in unnotched specimens (see Figs 3 and 4 of ref. [7]). Batch to batch variation of the aluminium alloy, however, obscures the influence of lamination per se.…”

Section: Crack Initiationmentioning

confidence: 99%

Fatigue Resistance and Structure

Plumbridge¹

1979

Abstract-This paper comments on the eleven papers presented in the "Materials Behaviour" section of the Extension Seminar of I.C.M.3 and reported in Vol. 2, No. 1 of this Journal. It is hoped that this permanent recording of the opinions stated during the Conference will stimulate further discussion as to the directions future work in this field should take. For conciseness, points of detail and specific aspects not related to the "Microstructure-Fatigue Resistance" theme have been omitted.

“…My paper, Fatigue Resistance and Structure , was one of these 1 . It entailed summarizing 11 quite disparate presentations 2–12 made at the Extension Seminar of ICM 3 (Sheffield, 1979), and hopefully, producing something coherent. Although I rarely read my own published work, this present retrospection indicates to me that the outcome was not bad – others may or may not concur.…”

mentioning

confidence: 99%

Fatigue resistance and structure (30 years on)

Plumbridge

2009

A B S T R A C T A summary of the findings of the 11 papers reviewed in the original article is presented, and subsequent developments in a selected few are considered from a personal perspective. While there has been substantial progress in some areas (short cracks, time-dependent effects, fatigue-creep interactions) many challenges remain. New fields of interest (notably the transition towards micro/nano-integrity and electronics applications) have emerged, and it is contended that the next 30 years will be equally demanding and exciting.Many colleagues of Keith Miller will recall his habit of landing you with 'interesting' challenges. My paper, Fatigue Resistance and Structure, was one of these. 1 It entailed summarizing 11 quite disparate presentations 2-12 made at the Extension Seminar of ICM 3 (Sheffield, 1979), and hopefully, producing something coherent. Although I rarely read my own published work, this present retrospection indicates to me that the outcome was not badothers may or may not concur. My strategy for the storyline of the paper was to consider fatigue crack initiation and propagation separately, and on a size scale covered by the 11 papers roughly atomistic (solute atoms and strain ageing) through to the macrobehaviour of laminates. Then, as probably now, uncertainty surrounded the precise interpretation of crack initiation and growth, the often different effects of microstructure on each stage and the validity of employing data from ultra-high frequency testing to more conventional applications.Following detailed consideration of each paper, the suggestions regarding how microstructural features might be utilized to improve fatigue resistance included: 1 inhibition of dislocation motion and avoidance of dislocation multiplication; 2 dispersion of plastic deformation to prevent its intensification, as in precipitate-free zones; 3 avoidance of large particles or inclusions that promoted initiation;