Effects of Tensile Prestress Level on Impact Value of 50 vol% Continuous Unidirectional 0 Degree Oriented Carbon Fiber Reinforced Epoxy Polymer (CFRP)

Abstract

Effects of tensile prestress level on Charpy impact value (a uc ) of 50 vol% continuous unidirectional 0 degree oriented carbon fiber reinforced epoxy polymer (CFRP) were investigated. Experimental results showed the a uc at mid-fracture probability P f = 0.50 induced by a large prestress of 17.6 MPa (109 kJm ¹2 ) was increased 30% over that (84 kJm ¹2 ) of slight prestress of 0.25 MPa. The statistically lowest impact value a s at P f = 0 calculated by 3-parameter Weibull equation was raised 26% from 73 to 92 kJm ¹2 showing increased reliability of part strength. Fracture surface observation showed a flat surface extending through the thickness from the impact side generally extends deeper as prestress level was raised. This may be due to the transition depth in the specimen thickness from compression to tension is deeper during impact as prestress level was increased acting to raise the impact values.

Viscoelastically prestressed polymeric matrix composites: An investigation into fibre deformation and prestress mechanisms

“…These elastically prestressed PMCs (EPPMCs) are produced by applying tension to fibres embedded in uncured resin, the tensile load being released after resin curing. Owing to attempted elastic recovery by residual fibre tension, a compressive stress is generated within the resin matrix, which can improve the composite mechanical properties [8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Prestressed polymeric matrix composites: Longevity aspects

“…These improvements are explained by the residual stresses (i) impeding or deflecting propagating cracks and (ii) reducing strains within the composites from external tensile or bending loads [3−5]. More recent investigations include unidirectional glass fiber EPPMCs as potential dental materials, the prestress increasing flexural strength by ∼30% and unidirectional carbon fiber EPPMCs, with increases of ∼30% in impact toughness . In addition to opportunities for EPPMCs to improve mechanical properties (without the need to increase section dimensions or weight), there has been interest in their use as bistable (morphing) composites, either as prestressed laminates or as unidirectional fiber prestressed structural elements .…”

Tensile strength of Polypropylene Reinforced by Carbon Fiber Covered with and without Sizing Epoxy Film

“…The conventional carbon fiber reinforced polymer (CFRP) of epoxy resin matrix with high strength is usually applied to the body of airplanes and blade of wind power generator. Strengthening carbon fiber [1,2] and CFRP [3][4][5][6][7][8][9] has been investigated. However, the long-term solidification of Epoxy-CFRP [3][4][5] is a serious problem to produce them.…”

“…Strengthening carbon fiber [1,2] and CFRP [3][4][5][6][7][8][9] has been investigated. However, the long-term solidification of Epoxy-CFRP [3][4][5] is a serious problem to produce them. To shorten the solidification term in production process, thermoplastic polymers are useful, since the solidification term of inexpensive Polypropylene (PP) is tremendously shorter than that of expensive Epoxy.…”