In-plane Shear Tests Research Articles

Influence of 3D warp interlock fabrics parameters made with flax rovings on their final mechanical behaviour

The three-dimensional weaving process enables to produce near-net shaped complex preforms used as reinforcement of composite materials. However, the lack of knowledge on the mechanical behaviour of these three-dimensional woven structures may restrict their use for composite material. To fill this gap, we have tempted to highlight their specific mechanical properties according to their endogenous parameters. Based on these different architectures produced on the same weaving loom, several non-impregnated coupons have been mechanically characterized in all the directions of the three-dimensional warp interlock fabrics with quasi-static tensile tests in warp and weft directions as well as in-plane shear tests. According to our analyses, it has been revealed that the combination of several parameters as the woven pattern, the end and pick densities and the presence or not of stuffer warp yarns inside the three-dimensional fabrics may significantly influence the mechanical behaviour of the three-dimensional warp interlock architectures.

Improving the multifunctionality of structural supercapacitors by interleaving graphene nanoplatelets between carbon fibers and solid polymer electrolyte

Novel structural supercapacitors, containing graphene nanoplatelets incorporated carbon fiber mats as electrodes, crosslinked diglycidylether of bisphenol-A epoxy polymer electrolyte and filter paper separator, have been manufactured for the first time by vacuum-assisted resin transfer molding process. These supercapacitors can bear structural loads and store electrochemical energy at the same time. Loading of high surface area graphene nanoplatelets on carbon fiber mats is an effective process to improve the charge storage capacity of the electrodes. Electrochemical and structural properties of the structural supercapacitors are explored through in-plane shear testing, dynamic mechanical thermal analysis, chronoamperometry and impedance spectroscopy, respectively. As graphene nanoplatelet loadings on carbon fiber mat electrodes increase from 0 to 10 wt.%, the structural supercapacitors exhibit significant improvements in specific capacitance (8.9–118.7 mF·cm−3), energy density (19.7–263.8 Wh·m−3) and normalized in-plane shear modulus (1.7–3.1 GPa). Thus, this study has revealed that using the graphene nanoplatelet loaded carbon fiber mats as structural supercapacitor electrodes is a relatively novel and easy approach to enhance the multifunctionality of structural supercapacitors.

Direct shear tests of glass fiber reinforced polymer connectors for use in precast concrete sandwich panels

The precast concrete sandwich panel (PCSP) is a popular structural type used for prefabricated construction. In this study, three kinds of glass fiber reinforced polymer (GFRP) connector, including a flat plate, a corrugated plate, and a hexagonal tube connector, were investigated for potential use in PCSPs. In-plane direct shear tests were conducted to evaluate the performance of the connectors based on a typical push-out configuration (i.e., three concrete wythes linked with connectors and two rigid foam layers in between). Twenty-five specimens were tested, and the parameters investigated consisted of GFRP laminate thickness, projected length, and shear force direction. The shear force vs. relative slip relationships and failure modes of all types of connector were compared and are discussed in detail in this paper. Meanwhile, finite element (FE) analysis was conducted to reproduce the test results. All three types of GFRP connector exhibited a progressive failure manner in spite of the linear brittle nature of the FRP materials; the corrugated plate connector achieved higher deformability than the flat plate connector, particularly when the GFRP laminate thickness was small; and the hexagonal tube connector exhibited similar behavior along two orthogonal directions, making them well suited for use as two-way connectors. The developed FE model was able to well predict the peak shear load and stiffness of all types of connector based on comparisons with the test results.

In-plane shear strength analysis of Basalt Fiber-Reinforced Epoxy Laminates with Biowaste Catalyst Free Carbon

This study aims to analyse the effects of carbon nanospheres (CNSs) on the in-plane shear properties of basalt fiber-reinforced epoxy composite laminate (BFR). The CNSs were obtained from an economical fibrous residue attained from the sago palm tree, which is known as biowaste sago bark. Hand lay-up method was used to fabricate the unidirectional basalt fiber-reinforced epoxy composite laminates. The epoxy resin was mixed with carbon nanosphere particles (i.e., 0.6 wt% - 1 wt%). In-plane shear tests have been conducted as per ASTM standards. In addition, emphasis on the microstructural investigation using Scanning Electron Microscopy (SEM) is given, in order to study the fracture surfaces of the composite laminates. The results demonstrated significant improvement in in-plane shear strength when carbon nanosphere particles were included in the basalt fiber-reinforced epoxy composite laminate. The best result was obtained at 1.0 wt% CNSs. It displayed an increment of 37.1% in in-plane shear strength, and 36.4% increment in modulus of rigidity, respectively, in comparison to neat basalt fiber-reinforced epoxy composite laminate. The improved accomplishment of CNSs/basalt fiber-reinforced epoxy composite laminate is due to good distribution of CNSs particles in the epoxy matrix.

The effect of tension compression asymmetry on modelling the bending response of sheet moulding compound composites

Phenomenological models are required to predict the behaviour of a glass fibre reinforced Sheet Moulding Compound (SMC) composite material for use in the automotive industry. Material testing is conducted in tension, compression, in-plane shear, and three-point bending. The SMC composite exhibits tension-compression asymmetry and in-plane anisotropy. A model, which incorporates an anisotropic and asymmetric yield function, is developed. The model is calibrated to the experimental tension, compression and in-plane shear tests and are validated using the three-point flexure test. The model captures the flexure response within 8.1% of the experimental observations. The importance of including tension compression asymmetry within the model is demonstrated.

Carbon fiber reinforced modified bisphenol-a diglycidylether epoxy composites for flame retardant applications

We have developed novel multifunctional flame retardant polymer composites that exhibit better fire performance. Flame retardant polymer composites are prepared by infusing woven carbon fibers with phosphoric-acid-modified crosslinked diglycidylether of bisphenol-A epoxy matrix through the resin infusion under flexible tooling (RIFT) process. In this paper, we have explored various design factors of the fire retarding epoxy resin by modifying the resin physically as well as chemically. Different flame retardant epoxy samples are evaluated by compression test, UL 94, thermogravimetric analysis and dynamic mechanical thermal analysis. The fabricated flame retardant polymer composites have been characterized using in-plane shear test, to estimate the structural properties, and UL-94 test, to estimate the fire performance. In this study, a flame retardant composite, simultaneously exhibiting a UL-94 rating of V-0 and a shear modulus of 9.5 GPa, has been reported.

Multifunctional structural lithium ion batteries for electrical energy storage applications

Multifunctional structural batteries based on carbon fiber-reinforced polymer composites are fabricated that can bear mechanical loads and act as electrochemical energy storage devices simultaneously. Structural batteries, containing woven carbon fabric anode; lithium cobalt oxide/graphene nanoplatelets coated aluminum cathode; filter paper separator and cross-linked polymer electrolyte, were fabricated through resin infusion under flexible tooling (RIFT) technique. Compression tests, dynamic mechanical thermal analysis, thermogravimetric analysis and impedance spectroscopy were done on the cross-linked polymer electrolytes while cyclic voltammetry, impedance spectroscopy, dynamic mechanical thermal analysis and in-plane shear tests were conducted on the fabricated structural batteries. A range of solid polymer electrolytes with increasing concentrations of lithium perchlorate salt in crosslinked polymer epoxies were formulated. Increased concentrations of electrolyte salt in cross-linked epoxy increased the ionic conductivity, although the compressive properties were compromised. A structural battery, exhibiting simultaneously a capacity of 0.16 mAh L−1, an energy density of 0.32 Wh L−1 and a shear modulus of 0.75 GPa have been reported.

Some permanent effects of hygrothermal and outdoor ageing on a structural polyurethane adhesive used in civil engineering applications

This paper presents an experimental study about the effects of hygrothermal and outdoor ageing on a polyurethane (PUR) adhesive used in civil engineering applications. Small-scale adhesive coupons were exposed to different types of ageing environments for up to two years: (i) immersion in demineralised water at 20 and 40 °C, (ii) immersion in salt water at 20 and 40 °C, (iii) continuous condensation environment at 40 °C, and (iv) outdoor ageing in Lisbon, Portugal. At predetermined times, after a desorption period until constant mass, the effects of such exposure on the physical and mechanical responses of the PUR adhesive was investigated using the following techniques: (i) water sorption, (ii) dynamic mechanical analyses (DMA); (iii) flexural; and (iv) in-plane shear tests. The diffusion mechanisms observed were not purely Fickian; a long relaxation period was noticed, with water molecules being continuously incorporated in the adhesive until the end of the experiments; two alternative analytical modelling approaches were successfully used to simulate the diffusion processes. After immersion in water and salt water for two years, the viscoelastic behaviour of the adhesive showed signs of post-curing phenomena, and some of the physical degradation was found to be reversible due to drying, although it was not explicitly quantified; accordingly, the Tg showed increasing trends (11-14%). The mechanical properties of the adhesive showed signs of irreversible degradation mechanisms, more relevant on the in-plane shear properties, with reductions up to 26% in strength and 44% in modulus under the harsher conditions. Flexural properties also exhibited irreversible degradation, with maximum reductions up to 30% in strength and 36% in modulus. Increased temperature did not have a significant effect in the flexural and shear strength, but caused higher degradation in the corresponding moduli. The degradation caused by salt water immersion and continuous condensation was comparable to that in demineralized water immersion (at the same temperature).

Particle-Based Modelling of In-Plane Shear in Textiles

This paper investigates the prediction of the constitutive behavior of textiles subjected to in-plane shear loading, using a particle-based modelling method. Plain weave textiles where the fibers are represented as a series of conjoined particles were modelled using discrete mechanics, as an alternative to traditional continuum mechanics. The configurations of individual fibers were obtained from first principles, using a modified Metropolis algorithm to minimize the strain energy terms. A series of simulations replicating articulated frame in-plane shear tests were performed in order to characterize the in-plane shear behavior of woven textiles. The paper discusses the effects of varying boundary conditions at fiber ends upon the application of a displacement field, and of varying iteration parameters for particle positions towards lower levels of strain energy. Load-displacement curves were derived from the simulations; displacement fields, locking angles and shear stresses were also quantified. The results of simulations and experiments performed on woven textiles subjected to in-plane shear showed good agreement, and improvements in accuracy over other modelling techniques.

Fabrication of high-stiffness fiber-metal laminates and study of their behavior under low-velocity impact loadings

This study investigates the impact behavior of fiber-metal laminates (FMLs) (Carbon FMLs and Glass FMLs), which were fabricated by using high-stiffness steel, carbon prepreg, and glass prepreg through autoclave molding. The mechanical behavior of the FMLs was evaluated by performing tensile, compressive, in-plane shear, and low-velocity impact tests. Drop-weight impact tests were conducted to induce cracking of the FMLs, and the crack initiation along with crack propagation behavior of the different laminate sequences ([0/0], [0/90], [0/90/0], [90/0/90] and [0/90/90/0]) were also studied. The results show that the fabricated FMLs have higher strength and stiffness than conventional FMLs. Their impact strengths increased, and weights decreased simultaneously. The absorption energy was proportional to the crack length that was induced by the low-velocity impact. Moreover, it was found that the fiber orientation mainly affected the direction of crack propagation in the FMLs. This investigation facilitates the design of high-stiffness and lightweight FMLs for automotive parts.

Study of the ballistic behaviour of UHMWPE composite material: experimental characterization and numerical simulation

This paper presents a comprehensive mechanical study of UHMWPE (Ultra High Molecular Weight Polyethylene) composite material under dynamic loadings. The aim of the study is to provide reliable experimental data for building and validate the composite material model under impact. Four types of characterization tests have been conducted: dynamic in-plane tension, out-of-plane compression, shear tests and plate impact tests. Then, several impacts of spherical projectiles have been performed. Regarding the numerical simulation, an intermediate scale multi-layered model (between meso and macro scale levels) is proposed. The material response is modelled with a 3d elastic orthotropic law coupled with fibre damage model. The modelling choice is governed by a balance between reliability and computing cost. Material dynamic response is unconventional [1, 2]: it shows large deformation before failure, very low shear modulus and peeling strength. Numerical simulation has been used both in the design and the analysis of tests. Many mechanical properties have been measured: elastic moduli, failure strength and EOS of the material. The numerical model is able to reproduce the main behaviours observed in the experiment. The study has highlighted the influence of temperature and fibre slipping in the impact response of the material.

EXPERIMENTAL STUDY ON LATERAL PERFORMANCE OF SHEAR WALL OF MODERN TIMBER ARCHITECTURE COMBINED WITH BRACE AND PLASTER USING WOOD LATH

In this study, in-plane shear tests of the seismic shear walls of modern timber architecture combined with brace and plaster using wood lath were conducted, and the failure mode, deformation performance and strength properties were discussed. The specimens are shown in Fig. 1 and Table1. Two types of the steel plate are used for the joints of the brace (see Fig. 2 and Fig. 3). Specimen1 is the wall using the only brace with the joint steel plate as shown in the existing architecture. Specimen2 is the wall using the only brace with the reinforced steel plate in joint. Specimen3 is the only plaster wall using wood lath. Specimen4 is the wall combined with brace (existing joint steel plate) and plaster using wood lath. Specimen5 is the wall combined with brace (reinforced steel plate) and plaster using wood lath. The results obtained from this study are summarized as follows. In the Specimen1, the joint steel plates were rotated in the early drift angle (see Photo3), and axial force were not acted on the tensile brace. At the drift angle of 1/30rad, the beam was broken (see Photo4) by bending moment because the compressive brace pushed up the beam. In the Specimen2, the strength properties were dramatically improved (see Fig. 8) because of the reinforced steel plate in joint. However, the bending fracture of the beam, which is the same as shown in Specimen1, occurred at the drift angle of 1/50rad. In the Specimen3, many cracks occurred at the corner of the plaster because of compressive stress (see Fig. 11). The strength of the plaster was the highest at the drift angle of 1/100rad, and the load decreased rapidly after that of 1/100rad. However, the load increased again after that of 1/50rad because wood lath was contacted with columns (see Fig. 10). In the Specimen4, the diagonal crack in the central area of plaster occurred in first, and then the crack at the corner of the plaster occurred (see Fig. 13). However, the number of the cracks at the drift angle of 1/100rad was lower than that of Specimen3. In the Specimen5, the cracks at the corner of the plaster occurred at the drift angle of 1/75rad (see Fig. 15). It is considered that the compressive stress will decrease by increasing the stiffness of the brace. The strength of the walls combined with brace and plaster shows good agreement with the sum of each strength of brace and plaster using wood lath.

Interfacial bonding strength of short carbon fiber/acrylonitrile-butadiene-styrene composites fabricated by fused deposition modeling

Abstract This work aims to characterize the interfacial bonding strength between printed wires of acrylonitrile-butadiene-styrene (ABS), carbon nanotube reinforced ABS (CNTABS) and short carbon fiber reinforced ABS (CFABS) specimens fabricated by fused deposition modeling. The in-plane tensile shear test and double notch shear test methods using ±45° specimens were used. The in-plane tensile shear strength of CFABS specimen is close to that of CNTABS specimen, and both of them are greater than that of ABS specimen. Double notch shear strengths are smaller than in-plane tensile shear strength of CFABS specimens at all three printing speeds studied. Also, the shear strengths of CFABS specimens decrease with increasing printing speed and layer thickness. X-ray micro-computed tomography examination concluded that CFABS specimens have the largest porosity compared with ABS and CNTABS specimens at corresponding raster orientation, especially for ±45° specimens. Matrix fracture and fiber pull-out, as well as fiber-matrix interfacial debonding are the dominating failure modes of CFABS specimen.

A new specimen for out-of-plane shear strength of advanced high strength steel sheets

Compared with the conventional steels, “shear fracture” is one of the main issues for advanced high strength steels (AHSS). Due to rolling, anisotropy is an intrinsic property for sheet metals. Not only the plastic responses of sheet metals but also the fracture strengths are orientation dependent. In the small radius forming process, for example, the stretch-bending deformation of sheet metals under small radius condition, the normal stress cannot be neglected. Three-dimensional loading condition constructs complex shear stress states of sheet metals especially the out-of-plane shear stress. The out-of-plane performance must be considered in order to better understand the “shear fracture” phenomenon of AHSS. Compared to in-plane shear test, the out-of-plane shear test is more difficult to carry out due to the severe restriction of the dimensions in the thickness direction. In this paper, a new specimen is presented for out-of-plane shear test. Failure of the specimen occurs in shear between two centrally located notches machined halfway through its thickness from opposing sides. Meanwhile, the finite element (FE) model and possible failure modes of this specimen are investigated in detail. At last, brief experimental results between out-of-plane shear fracture strength and the in-plane shear fracture strength are compared for DP980 sheets.

Fracture loci of DP980 steel sheet for auto-body at intermediate strain rates

This paper introduces the effect of the strain rate on the ductile fracture of DP980 1.2t steel sheet. Tensile tests of DP980 sheet are performed at a range of strain rates from 0.001 s−1 to 100 s−1 with three different shapes of specimens: the diagonally notched specimen for the in-plane shear test; the dog bone specimen for the uniaxial tension test; and grooved specimen for the plane strain tension test. To trace the strain on the surface of the specimen, 2-D digital image correlation (DIC) technique is adopted to encompass the remarkable transition of the fracture characteristics including the fracture strain, loading path and strain rate sensitivity. The negative stain rate sensitivity is observed on the equivalent strain to fracture which corresponds to the experimental results at low strain rate ranging from 0.001 s−1 to 0.1 s−1. The transition of thermal condition from isothermal to adiabatic comes into play to increase the equivalent strain to fracture at the intermediate strain rate from 0.01 s−1 to 1 s−1. The fracture loci incorporating with the Lou-Huh ductile fracture criterion are developed to identify the strain rate effect in the wide regime of triaxiality.

真壁用木製パネルの開発と面内せん断試験

This paper describes a new developed wooden sliding panel wall inserted in wooden frame. In-plane shear tests for two types of these panel walls were carried out compared with the typical plywood sheathed wall. The main results are as follows. The rigidity and strength of the new developed walls are about 20% and 50% of those of contemporary bearing walls under the horizontal deformation of 0.05 rad. Although, beyond this deformation, the rigidity and strength of new developed walls gradually improve and withstand large load.

Evaluation of common tests for fracture characterisation of advanced high-strength sheet steels with the help of the FEA

The paper presents results of evaluation of common tests for fracture characterization of advanced high-strength sheet steels with the help of the FEA. The tests include three in-plane shear tests, two uniaxial tension tests, two plane strain tension tests and two equibiaxial tension tests. Three high-strength steels with different yield loci, strain hardening rates and strengths in three different thicknesses each were used. The evaluation was performed based on the spatial distribution of the equivalent plastic strain and damage variable in the specimen at the moment of crack initiation as well as on the time variation of the stress state at the crack initiation location. For in-plane shear, uniaxial tension and plane strain tension, no test can be unconditionally recommended as disadvantages of all studied tests in these groups cannot be neglected. However, in each of these groups, a test can be chosen, which represents an acceptable compromise between its advantages and disadvantages: the shear test on an IFUM butterfly specimen for in-plane shear, the tensile test on a holed specimen for uniaxial tension and the tensile test on a waisted specimen for plane strain tension. On the contrary, the bulge test on a circular specimen with a punch of Ø 100 mm can be unconditionally recommended for equibiaxial tension. In the future, optimisation of the studied tests for in-plane shear, uniaxial tension and plane strain tension appears to be necessary.

In-plane shear investigation of 3D surface-core braided composites

In-plane shear properties of three-dimensional (3D) surface-core braided composite are investigated by numerical simulation and experimental tests. Based on RVE models, the mechanical responses under in-plane shear load and the basic shear properties related to braiding parameters are predicted by using finite element method. Numerical results indicate that two groups of surface-cores possess distinct sensitivities to shear loads and identify the main load bearing components. In-plane shear tests are conducted to compare the effects of surface cuttings on the mechanical properties of present material and 3D 4-directional braided composite. The experimental data reveal that the cuttings degrade the shear moduli and strengths of the two materials to varying degrees. 3D surface-core braided composite can effectively restrain the decline of shear properties caused by cuttings. Scanning electron microscopy (SEM) is used to identify the distinct damage mechanisms of tested materials.

In-plane shear behavior of 3D spacer knitted fabrics

The shear behavior of 3D spacer knitted fabrics was investigated by using a picture frame fixture. Three different methods were used to find the shear angle during loading rate of 10 mm/min. All the tests were recorded by a CCD monochrome camera. The images acquired during loading process were used for analysis in order to obtain the full-field displacement and shear angles at chosen points on the surface of test specimen. An experimental and analytical investigation of picture frame shear fixture was conducted to determine its suitability for measuring intra-ply shear properties of 3D knitted spacer fabrics. In this work, a fixture was designed to analyze the in-plane shear behavior of these fabrics. The nonlinear behavior of shear force versus shear angle and the deformation mechanism were analyzed. The curves for shear force versus shear angle and position of buckling for in-plane shear test are recorded by considering two different frame lengths in order to compare with each other. Load–displacement curves of intra-ply shear tests are also analyzed. In addition to this, a program was developed in MATLAB using Hough transform to analyze the shear angle in the real-time image taken during displacement of specimen at various positions. The results of image analysis were compared with the actual experimental results. These findings are important requirements for further improvements in designing of picture frame fixture and to study the in-plane shear properties of 3D fabrics.

Study of the cohesion of carbon fiber yarns: in-plane shear behavior

Cohesion of the fibers network is a key element in numerous manufacturing processes of textile structures and composite parts, because it significantly affects the implementability and the obtained result. However, cohesion remains at the moment an intuitive concept. This paper aims to deal with this concept, first proposing a first interpretation of yarn cohesion. Thanks to this definition, the in-plane shear test is proposed to characterize and measure cohesion. Among many difficulties, it appears to be an interesting way to analyze the cohesion of yarns extracted from 7 different batches and to establish the link between cohesion and implementation in manufacturing processes of Herakles which supports this study. In addition, the phenomenon responsible for the yarn cohesion are tackled and the influence of the yarn constitution is analyzed.