TABLE 4.1 Typical Weibull Parameters for Composite Laminates Shape Location Parameter, Material Laminate Parameter,o oo MPa (ksi) Boron-epoxy O 24.3 1324.2 (192.0) [90 15.2 66.1 (9.6 [02/±45s 18.7 734.5 (106.6 [0/±45/90s 19.8 419.6 (60.9) [902/45]s 19.8 111.9 (16.1) T-300 Carbon-epoxy5 [Os] 17.7 1784.5 (259) [016d 18.5 1660.5 (241) E-glass-polyester SMCe SMC-R25 7.6 74.2 (10.8) SMC-R50 8.7 150.7 (21.9) a From B.E.Kaminski,Analysis of the Test Methods for High Modulus Fibers and Composites, ASTM STP,521,18L,1973. bFrom R.E.Bullock,J.Composite Mater.,8,200.1974. e From C.D.Shirrell,Polym.Compos..4.172.1983. SOLUTION Step 1:Starting with the smallest number,arrange the observed strength values in ascending order and assign the following probability of failure value for each strength. i P= n+l: where i=1,2,3,,n n=total number of specimens tested P 46.15 1/23=0.0435 2 47.14 2/23=0.0869 2 47.94 3/23=0.1304 21 72.84 21/23=0.9130 22 72.95 22/23=0.9565 Step 2:Plot P vs.tensile strength o to obtain the Weibull distribution plot (see the following figure). 2007 by Taylor&Francis Group.LLC.SOLUTION Step 1: Starting with the smallest number, arrange the observed strength values in ascending order and assign the following probability of failure value for each strength. P ¼ i n þ 1 , where i ¼ 1, 2, 3, . . . , n n ¼ total number of specimens tested i s P 1 46.15 1=23 ¼ 0.0435 2 47.14 2=23 ¼ 0.0869 3 47.94 3=23 ¼ 0.1304 ... ... ... ... ... ... 21 72.84 21=23 ¼ 0.9130 22 72.95 22=23 ¼ 0.9565 Step 2: Plot P vs. tensile strength s to obtain the Weibull distribution plot (see the following figure). TABLE 4.1 Typical Weibull Parameters for Composite Laminates Material Laminate Shape Parameter, a Location Parameter, s0 MPa (ksi) Boron–epoxya [0] 24.3 1324.2 (192.0) [90] 15.2 66.1 (9.6) [02=±45]S 18.7 734.5 (106.6) [0=±45=90]S 19.8 419.6 (60.9) [902=45]S 19.8 111.9 (16.1) T-300 Carbon–epoxyb [08] 17.7 1784.5 (259) [016] 18.5 1660.5 (241) E-glass–polyester SMCc SMC-R25 7.6 74.2 (10.8) SMC-R50 8.7 150.7 (21.9) a From B.E. Kaminski, Analysis of the Test Methods for High Modulus Fibers and Composites, ASTM STP, 521, 181, 1973. b From R.E. Bullock, J. Composite Mater., 8, 200, 1974. c From C.D. Shirrell, Polym. Compos., 4, 172, 1983.
2007 by Taylor & Francis Group, LLC