Mixed mode testing of a multi-directional woven laminate
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ORIGINAL PAPER
Mixed mode testing of a multi-directional woven laminate Leslie Banks-Sills
· Orly Dolev
Received: 11 September 2019 / Accepted: 23 January 2020 © Springer Nature B.V. 2020
Abstract Mixed-mode fracture toughness tests were carried out on a multi-directional laminate making use of a Brazilian disk specimen. The composite laminate consisted of plain, balanced woven plies with tows in the 0◦ /90◦ -directions and the +45◦ / − 45◦ directions. The delamination was placed between two of these plies by means of a polytetrafluoroethylene (PTFE) film. Tests at various loading angles were performed in order to obtain a wide range of mode mixities. Each ply was homogenized by means of a micromechanical model to obtain its effective properties. The specimens were analyzed by means of the finite element method. An interaction energy or M-integral was extended for this interface to obtain the stress intensity factors. The latter were used to determine the critical interface energy release rate and two phase angles. Employing this information, a three-dimensional failure criterion proposed elsewhere was presented. The criterion may be used to predict failure of a composite Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10704-020-00429-3) contains supplementary material, which is available to authorized users. L. Banks-Sills (B)· O. Dolev Dreszer Fracture Mechanics, Laboratory School of Mechanical Engineering, Tel Aviv University, 6997801 Ramat Aviv, Israel L. Banks-Sills e-mail: [email protected] O. Dolev e-mail: [email protected]
structure containing a delamination along the interface and material studied here. Keywords Brazilian disk specimen · Fiber reinforced composites · Fracture toughness · Mixed modes · Woven composite
1 Introduction The establishment of failure criteria of composite laminates is of great interest to manufacturers in various industries, such as biomedical, sport, automotive and aerospace. Such criteria will contribute to a low cost product with the best performance available. While designing a composite structure, first its material system should be determined. This stage is crucial, since once a material system has been chosen, it affects stages from initial design to the final product. The fact that much effort is being made in order to achieve innovations in the field of composite materials leads sometimes to confusing outcomes as a result of its complexity. These innovations may be related to the chemistry involved in developing a new material system and its constituent equations or may be related to a new analysis modeling tool or algorithm to predict the material behavior under certain conditions. Thus, a better understanding of the material structure and its behavior is the first step in establishing failure criteria. The well known advantages of composite materials, such as high strength and toughness to weight ratios,
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L. Banks-Sills, O. Dolev
Fig. 1 a Balanced plain weave with tows in the 0◦ /90◦ directions. b Delaminatio
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