Development of the delamination evaluation parameters (I) — the delamination aspect ratio and the delamination shape factors —

Abstract

Although the previous researches evaluated the fatigue behavior of A1/GFRP laminates using the traditional fracture mechanism, their researches were not sufficient to do it : the damage zone of A1/GFRP laminates was occurred at the delamination zone instead of the crack-metallic damages. Thus, previous researches were not applicable to the fatigue behavior of Al/GFRP laminates. The major purpose of this study was to evaluate delamination behavior using the relationship between crack length(a) and delamination width(b) in A1/GFRP laminate. The details of investigation were as follows : 1) Relationship between the crack length(a) and the delamination width(b), 2) Relationship between the delamination aspect ratio(b/a) and the delamination area rate ( (A_d)_n/ (A _d) a_ll) , 3) The effect of delamination aspect ratio(b/a) on the delamination shape factor (f _s) and the delamination growth rate (dA _d/da). As results, it was known that the delamination aspect ratio(b/a) was decreased and the delamination area rate ( (A _d)_n/ (A _d)_All) was increased as the normalized crack size(a/W) was increased. And, the delamination shape factors (f _s) of the ellipse-II (f _s3) was greater than of the ellipse-1 (f _s2) but that of the triangle (f_s1) was less than of the ellipse-I (f _s2).