Non-crimp 3D Orthogonal Weave Research Articles

Fully-reversed tension-compression fatigue of 2D and 3D woven polymer matrix composites at elevated temperature

High-temperature tension-compression fatigue behavior of polymer matrix composites with a 2D and a 3D fiber architecture was examined. The two composites studied in this work have the same NRPE polyimide matrix and carbon fiber reinforcement, but different fiber architectures. The 3D composite is a single-ply non-crimp 3D orthogonal weave material whereas the 2D laminated composite contains fifteen 0/90 woven plies. The study aims to evaluate the fitness of the two materials for service in aerospace thermal-protection systems. Thus mechanical testing was conducted under environmental conditions mimicking the realistic service environment: one side of the test specimen was held at 329 °C whilst the other side remained open to ambient laboratory air. The tension and compression stress-strain responses of the two composites were investigated and the basic tensile and compressive properties measured. The high-temperature properties were similar to those obtained at room temperature. Fully-reversed tension-compression cyclic tests were carried out at elevated temperature. The frequency was 1.0 Hz, the ratio of minimum to maximum stress was −1.0, and the runout condition was defined as survival of 200,000 cycles. The evolution of maximum and minimum strains with cycles as well as the progressive change in modulus were examined for each test. The 3D composite produced a higher fatigue limit, while the 2D laminated composite displayed a slightly better fatigue performance at higher stress levels. All specimens that survived 200,000 cycles without failure were tested in tension to failure to assess the retained tensile strength and stiffness. Examination of tested specimens with an optical microscope showed extensive delamination of the 2D composite. The 3D composite proffered enhanced delamination resistance.

Fatigue of unitized polymer/ceramic matrix composites with 2D and 3D fiber architecture at elevated temperature

Tension-tension fatigue behavior of two unitized composites comprising a polymer matrix composite (PMC) and a ceramic matrix composite (CMC) co-cured together was studied at elevated temperature. The PMC parts of both unitized composites have a 2D fiber architecture and consist of the P2SI® NRPE polyimide matrix reinforced with 12 plies of carbon fibers woven in an eight harness satin weave (8HSW). The P2SI® NRPE is a high-temperature, structural thermosetting polyimide developed for 288–316 °C service temperature applications. The CMC parts of the two unitized composites consist of a zirconia-based ceramic matrix reinforced with quartz glass fibers, but have different fiber architectures. The first unitized composite includes a laminated 2D CMC reinforced with 3 plies of an 8HSW fabric. The second unitized composite includes a 3D CMC that is a single-ply non-crimp 3D orthogonal weave composite. To assess the suitability of the two unitized composites for use in aerospace components designed to contain high-temperature environments, mechanical testing was conducted under temperature conditions mimicking the service environment. In all tests, the CMC side of the test specimen was at 329 °C while the PMC side was exposed to ambient laboratory air. The tensile stress-strain behavior of the two unitized composites was investigated and the tensile properties measured for both on-axis (0/90) and off-axis (±45) fiber orientations. Tension-tension fatigue behavior was evaluated in cyclic tests performed with an R (ratio of minimum to maximum stress) of 0.05 at a frequency of 1.0 Hz. Fatigue run-out was set to 2 × 105 cycles. Both hysteresis stress-strain behavior and modulus evolution with fatigue cycles were examined for each test. The 2D-PMC/2D-CMC composite exhibited better fatigue resistance than the 2D-PMC/3D-CMC under on-axis loading, while the 2D-PMC/3D-CMC had stronger fatigue performance under off-axis loading. Specimens that achieved fatigue run-out were tested in tension to failure in order to measure the retained tensile properties. Post-test examination with optical microscopy revealed severe delamination in the laminated 2D-PMC/2D-CMC and in the PMC part of the 2D-PMC/3D-CMC. The non-crimp 3D orthogonal weave CMC part exhibited improved delamination resistance.

Fatigue of a 3D Orthogonal Non-crimp Woven Polymer Matrix Composite at Elevated Temperature

Tension-tension fatigue behavior of two polymer matrix composites (PMCs) was studied at elevated temperature. The two PMCs consist of the NRPE polyimide matrix reinforced with carbon fibers, but have different fiber architectures: the 3D PMC is a singly-ply non-crimp 3D orthogonal weave composite and the 2D PMC, a laminated composite reinforced with 15 plies of an eight harness satin weave (8HSW) fabric. In order to assess the performance and suitability of the two composites for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions simulating the actual operating conditions. In all elevated temperature tests performed in this work, one side of the test specimen was at 329 °C while the other side was open to ambient laboratory air. The tensile stress-strain behavior of the two composites was investigated and the tensile properties measured for both on-axis (0/90) and off-axis (±45) fiber orientations. Elevated temperature had little effect on the on-axis tensile properties of the two composites. The off-axis tensile strength of both PMCs decreased slightly at elevated temperature. Tension-tension fatigue tests were conducted at elevated temperature at a frequency of 1.0 Hz with a ratio of minimum stress to maximum stress of R = 0.05. Fatigue run-out was defined as 2 × 105 cycles. Both strain accumulation and modulus evolution during cycling were analyzed for each fatigue test. The laminated 2D PMC exhibited better fatigue resistance than the 3D composite. Specimens that achieved fatigue run-out were subjected to tensile tests to failure to characterize the retained tensile properties. Post-test examination under optical microscope revealed severe delamination in the laminated 2D PMC. The non-crimp 3D orthogonal weave composite offered improved delamination resistance.

Numerical modelling of forming of a non-crimp 3D orthogonal weave E-glass composite reinforcement

A hyperelastic constitutive model is implemented to study the formability on three-dimensional complex shapes of a single layer E-glass non-crimp 3D orthogonal woven reinforcement. Experimental measurements of the main deformation modes have been used to identify the strain energy density function of the constitutive model. The comparison of the finite element simulations and experimental results of tetrahedron and double-dome shaping processes demonstrated the adequacy of the adopted hyperelastic model to describe the deformation mechanisms involved during draping and the efficiency to predict the global behaviour of the non-crimp 3D woven reinforcement during complex shape forming.

Formability of a non-crimp 3D orthogonal weave E-glass composite reinforcement

In this paper, the formability of a single layer E-glass non-crimp 3D orthogonal woven reinforcement (commercialized under trademark 3WEAVE® by 3Tex Inc.) is experimentally investigated. The study involves the forming process of the 3D fabric on two complex moulds, namely tetrahedron and double-dome. The tests are assisted by 3D digital image correlation measurement to have a continuous registration of the fabric local deformation. Moreover, the results of bending tests in warp and weft direction are detailed to enlarge the mechanical properties data set of the 3D reinforcement, necessary for understanding its deformability capacities in forming processes. The elevated bending stiffness of the 3D fabric means that use of a blank-holder during forming is not required. The reinforcement has a good drapability and it is able to form complex shapes without defects (wrinkles and fibre distortions). The collected experimental results represent an important dataset for numerical simulations of any complex shape with the considered 3D fabric composite reinforcement.

Micro-CT analysis of the internal deformed geometry of a non-crimp 3D orthogonal weave E-glass composite reinforcement

An investigation at the unit cell level of the sheared geometry of a single layer E-glass non-crimp 3D orthogonal woven reinforcement (commercialized under trademark 3WEAVE® by 3Tex Inc.) is performed by X-ray micro-computed tomography (micro-CT) observations. The aim is to observe, understand and quantify the effect of in-plane shear deformation on the composite reinforcement geometry, at meso-scale (i.e. unit cell level). It was observed that, increasing the shear deformation, Z-yarns maintain unchanged the distance between the yarns and as consequence the yarn cross-section has a reduced variation of width, mainly in the weft direction.Furthermore, the effect of the shear angle on the textile thickness during compression is measured, this being an important parameter after the forming and molding phases of a composite component production. Compression tests and micro-CT measurements of the thickness show similar values and are in agreement with the prediction obtained assuming the theoretical invariance of the volume in the considered range of shear deformations.

Forming of a Non-Crimp 3D Orthogonal Weave E-Glass Composite Reinforcement

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Deformability of a non-crimp 3D orthogonal weave E-glass composite reinforcement

Abstract Deformability of a single-ply E-glass non-crimp 3D orthogonal woven reinforcement (commercialized under trademark 3WEAVE® by 3Tex Inc.) is experimentally investigated. The study is focused on the understanding and measurement of the main deformation modes, tension and in plane shear, which are involved during draping of composite reinforcements by: (i) uniaxial and biaxial tension; (ii) in-plane shear investigation using uniaxial bias extension and picture frame tests; and (iii) measurements of the fabric thickness variation during shear. The test methods common for 2D fabrics are validated for the thick 3D reinforcement. The obtained results represent a data set for the simulation of a forming process with the 3D reinforcement.

Fatigue behavior of non-crimp 3D orthogonal weave and multi-layer plain weave E-glass reinforced composites

The paper studies tension–tension fatigue behavior of a single-ply non-crimp 3D orthogonal weave E-glass composite and of a laminated composite reinforced with four plies of a standard plain weave fabric. Both composites have same total thickness and very close fiber volume fraction. The paper presents the description of the materials, the results of quasi-static tensile and of tension–tension fatigue tests, including the damage development during fatigue tensile loading. The non-crimp 3D woven fabric composite, loaded in both principal in-plane directions (warp and fill), shows the best quasi-static tensile properties and, when loaded in the fill direction, exhibits much longer fatigue life than its laminated plain weave counterpart. During both quasi-static and fatigue loading, the latest damage initiation is observed for the 3D woven composite in both in-plane directions. The PW laminate develops delamination between the plies for each maximum stress in the cycle considered. Contrary to that, the 3D composite is not affected by delamination neither under quasi-static nor under fatigue loading conditions.

A comparative study of tensile properties of non-crimp 3D orthogonal weave and multi-layer plain weave E-glass composites. Part 2: Comprehensive experimental results

This Part 2 paper presents results of comparative experimental study of progressive damage in 2D and 3D woven glass/epoxy composites under in-plane tensile loading. As Part 1, this Part 2 work is focused on the comparison of in-plane tensile properties of two non-crimp single-ply 3D orthogonal weave E-glass fibre composites on one side and a laminate reinforced with four plies of E-glass plain weave on the other. The damage investigation methodology combines mechanical testing with acoustic emission registration (that provides damage initiation thresholds), progressive cracks observation on transparent samples, full-field surface strain mapping and cracks observation on micrographs, altogether enabling for a thorough characterisation of the local micro- and meso-damage modes of the studied composites. The obtained results demonstrate that the non-crimp 3D orthogonal woven composites have significantly higher in-plane strengths, failure strains and damage initiation thresholds than their 2D woven laminated counterpart. The growth of transverse cracks in the yarns of 3D composites is delayed, and they are less prone to a yarn–matrix interfacial crack formation and propagation. Delaminations developing between the plies of plain weave fabric in the laminate at certain load level never appear in the 3D woven single-ply composites.

A comparative study of tensile properties of non-crimp 3D orthogonal weave and multi-layer plain weave E-glass composites. Part 1: Materials, methods and principal results

Composites fabricated by VARTM technology with the use of single-ply non-crimp 3D orthogonal woven preforms 3WEAVE ® find fast growing research interest and industrial applications. It is now well understood and appreciated that this type of advanced composites provides efficient delamination suppression, enhanced damage tolerance, and superior impact, ballistic and blast performance characteristics over 2D fabric laminates. At the same time, this type of composites, having practically straight in-plane fibers, show significantly better in-plane stiffness and strength properties than respective properties of a “conventional” type 3D interlock weave composites. One primarily important question, which has not been addressed yet, is how the in-plane elastic and strength characteristics of this type of composites compare with respective in-plane properties of “equivalent” laminates made of 2D woven fabrics. This 2-part paper presents a comprehensive experimental study of the comparison of in-plane tensile properties of two single-ply non-crimp 3D orthogonal weave E-glass fiber composites on one side and a laminate reinforced with four plies of plain weave E-glass fabric on the other. Results obtained from mechanical testing are supplemented by acoustic emission data providing damage initiation thresholds, progressive cracks observation, full-field surface strain mapping and cracks observation on micrographs. The obtained results demonstrate that the studied 3D non-crimp orthogonal woven composites have considerably higher in-plane ultimate failure stresses and strains, as well as damage initiation strain thresholds than their 2D woven laminated composite counterpart. Part 1 presents the description of materials used, experimental techniques applied, principal results and their mutual comparisons for the three tested composites. Part 2 describes in detail the experimentally observed effects and trends with the main focus on the progressive damage: detailed results of AE registration, full-field strain measurements and progressive damage observations, highlighting peculiarities of local damage patterns and explaining the succession of local damage events, which leads to the differences in strength values between 2D and 3D composites.