Interface/Interphase Concepts in Composite Material Systems

Abstract

The influence of interfaces and interphases on the mechanical behavior of composite materials has been widely discussed in the literature, particularly in the last few years. Several books have been devoted to the subject. Despite this fact, the systematic representation of the mechanics of this subject remains grossly incomplete, and because of this, no consistent approach has been developed towards the determination of the influence of the interphase on the properties and performance of composite materials and laminates.The present paper advances a fundamental approach to this subject. The approach is based on the premise that the "composite effect"—that which defines the difference between the mechanical response of constituents acting without interaction and the response when they are bonded rigidly together — is the proper definition of the mechanical effect of the interphase. Within these two bounds, the "real" situation is determined by the extent of this interaction. The present paper attempts to specify these two bounds for typical loading and material situations. The nature of the boundary value problems associated with the two extremes as well as the intermediate cases is discussed.The incorporation of an interphasial region into micromechanical analyses of composite stiffness and strength will necessitate a reevaluation of the boundary value problem. The anisotropic, inhomogeneous, time-dependent quality of the interphase demands a more thorough treatment in existing micromechanical models. Yet, the level of complexity modeled is limited by our ability to measure interphasial properties. The interphase offers a wealth of opportunity on both analytical and experimental aspects of the problem.

Validating the Classical Failure Criteria for Applicability to the Notched Woven-Roving Composite Materials

“…P u p p o a n d E v e n s e n [ 25] ( ] is the global of 45 ∘ tenstion test (1) Main frame (2) Main shaft (3) Self-aligning bearing (4) Bending loading arm (5) Bending transducer (7) Torque transducer (8) Intermediate shaft (9) Deep groove ball bearing (10) Guide shaft (11) Twisting moment arm (6) Specimen (13) Twisting moment coupling (12) Bending connecting rod (14) Coupling shaft (15) Driven pully (16) Twisting moment loading arm (17) Bending moment loading arm (19) Motor table (20) V belt (21) Bending coupling plain specimen, the observed failure mode was a matrix-cracking mode normal to the loading axis and along the transverse fiber direction as shown in Figure 10. This may be attributed to brittleness of the matrix compared to the filling fiber fabrics.…”

“…To improve the performance of these materials, the source of damage must be insightfully understood to prevent its subsequent evolution and the deterioration of fundamental mechanical properties. The adhesion integrity between fiber and matrix is the justification for superior composite materials properties over their constituent components as discussed by a lot of researchers [2][3][4][5]. Their investigations were focusing on the fiber/matrix interaction at micro level scale [2][3][4][5].…”

“…The adhesion integrity between fiber and matrix is the justification for superior composite materials properties over their constituent components as discussed by a lot of researchers [2][3][4][5]. Their investigations were focusing on the fiber/matrix interaction at micro level scale [2][3][4][5]. Moreover, different techniques have been proposed to measure the fiber/matrix adhesion levels [6][7][8][9].…”

“…Moreover, different techniques have been proposed to measure the fiber/matrix adhesion levels [6][7][8][9]. Swan et al [5] and Jayaraman et al [10,11] have proposed different analytical methodologies and experimental techniques to improve the interpretation of the interface region. Dasgupta and Sirkis [12] studied the effect of coating modulus and thickness on the stress distribution around an optical fiber subjected to axial loading.…”

The effect of a graded interphase on the mechanism of stress transfer in a fiber-reinforced composite

“…During the process of manufacturing composites, physical and chemical interactions between reinforcements and matrix result in the formation of interphase encompassing the reinforcement/matrix interface (Drzal, 1986;Hughes, 1991;Theocaris, 1990;Williams et al, 1994). As an intermediate transition zone linking the reinforced fibers and matrix, the interphase plays a key role during the stress transfer between fibers and matrix (Hughes, 1991;Swain et al, 1990). Via proper design of an interphase zone in composites, the interfacial adhesion can be effectively improved, leading to a more efficient load transfer at interfaces.…”