Session: 03-05-01 Design, Material Processing, and Applications of Polymer Composites

Paper Number: 94402

94402 - "Statistical Analysis of Strain Rate Dependency of the Mechanical Properties of Unidirectional CFRE Materials" 

Of interest is the characterization of the mechanical properties carbon fiber reinforced composite materials for their mechanical properties under different loading conditions. Strain rate effects on epoxy carbon fiber composite material ultimate strength was investigated. 

Statistical analysis is commonly used for evaluating the parameters affecting the material response under varying loading conditions.

With the aim of finding new materials having high stiffness to density ratio, carbon fiber composite materials have gained popularity as alternatives to traditional high-stiffness and high-density materials. This work investigates the dependency on strain rate of some mechanical properties of unidirectional carbon fiber reinforced epoxy, CFRE.

Flexure testing was conducted using a Hounsfield universal testing machine type HK1000 equipped with 10kN load cell.  All flexural bending tests were performed according to ASTM standard D7264-2007. Seventy-two (72) laminate samples with 0° (dubbed laminate type 1) fiber orientation and thirty-six (36) samples having 90° (dubbed laminate type 2) fiber orientation were flexure tested. All specimens were tested to fracture and flexural stress and strains at varying strain rates. 

The composite laminates were fabricated at fiber orientations of 0° (dubbed type 1) while others at 90° (dubbed type 2). Statistical analysis (using Minitab® software) has been applied to determine the statistical significance (modulus at confidence interval varying from 5% to 10%) of the effect of strain rate on composite material response and strength.

Flexure testing according to ASTM standard D7264-2007 is used to experimentally test the response of composite materials. ANOVA statistical analysis using Minitab® proved to be a handful instrument for analyzing the response of composite material under variable loading considering the construction type1 and type 2 composite material. Using Minitab® regression analysis, conceived linear models predicting the variation of flexural strength in addition to construction type 1 fracture shear strength and the construction type 2 fracture strength models function of operating strain rate. Also, ANOVA statistical analysis is used to validate the operating strain rate effect on operating strain rate on standard deviation of construction type 1 and type 2 material stiffness at significance level α = 0.05.

Both type 1 and type 2 composite laminates were tested at several levels of flexural strain rates varying from 1.8*10-5 s-1 to 7.8*10-3 s-1. For type 1 and type 2 laminates, the flexural fracture stress values were found to increase around 4.5% and 8.6%, respectively, for the studied range of strain rates. It was also found that the flexural modulus of elasticity increased for both 0° and 90° increase in order of 5% and 10%, respectively, for type 1 and type 2 laminates over the strain rate range. This was evidenced by the increase in the variance of the experimentally collected flexural modulus and strength values with increasing operating strain rate.

Presenting Author: Ramsey Hamade American University Of Beirut

Presenting Author Biography: Prof Hamade is professor of mechanical engineering at AUB.

Authors:

Charbel Y. Seif American University of Beirut
Ilige S. Hage Notre Dame University-Louaize
Re-Mi Hage Notre Dame University - Louaize
Ahmad M.R. Baydoun American University of Beirut
Ramsey F. Hamade American University Of Beirut