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Effect of Natural Aging and Fatigue Crack Propagation Rate on Welded and Non-Welded Aluminum Alloy (AA2219-T87)

Ijaz Mudasir, Qayyum Faisal, Elahi Hassan, Ullah Mudaser, Eugeni Marco, Badshah Saeed, Gaudenzi Paolo

Advances in Science and Technology. Research Journal

2019

Vol. 13, no 3

129--143

Aluminum alloys are widely used for fabrication of aircraft, civil structures, and space vehicles. Fatigue life consideration of a material is the most important design criteria in many such critical applications. In this research work, a widely used Aluminum alloy AA2219-T87 was TIG welded using AA2319 as a filler material. The effect of natural aging on Fatigue Crack Propagation Rate (FCPR) of welded and non-welded compact tension (CT) specimens (AA2219˗T87) is studied. The relationship between stress intensity factor (ΔK) and crack ratio (a/W) for different value of the crack length in base metal and the welded zone is presented. Paris curves for both welded and non-welded specimens and compared to study the effect of natural aging (NA) on FCGR and compared with non-aged specimens. The results obtained provide a base for the development of Structural Health Monitoring systems for the propagation of crack growth in such components.

Crack arrest model for a piezoelectric strip subjected to Mode-I loadings

Bhargava R. R., Setia A.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 22, nr 2

19-22

Purpose: The present paper aims at proposing a crack arrest model for an infinitely long narrow, poled ceramic strip weakened by a finite hairline straight crack when the edges of the strip are subjected to combined mechanical and electrical loads. Design/methodology/approach: (Model) As a consequence of loads the rims of crack open forming a yield zone ahead of each tip of the crack. To arrest the crack from further opening the rims of the yield zones are subjected to normal cohesive quadratically varying yield point stress. Two cases are presented when edges of the strip are subjected to: Case-I-in-plane stresses and electrical displacement or Case-II-in-plane stresses and in-plane electric field. Problems are solved using Fourier integral transform method. Findings: The stress intensity factor, yield zone length, crack opening displacement, crack growth rate have been calculated. Their variation with respect to affecting parameters viz. yield zone length, width of the strip, material constant, electrical and mechanical loads has been depicted graphically. Research limitations/implications: The material of the strip is assumed mechanically brittle and electrically ductile consequently mechanically singularity is encountered first. The investigations in this paper are carried at this level. Also the crack yielding under the loads is considered small scale hence the yield zone is assumed to be lying on the line segment ahead of the crack. Practical implications: Piezoelectric ceramics are widely used as sensors and actuators, this necessity prompts the fracture study on such ceramics under difference loading conditions. Originality/value: The paper gives an assessment of the quadratically varying load required to be prescribed on yield zones so as to arrest the opening of the crack. The investigations are useful to smart material design technology where sensors and actuators are manufactured.