Journal Of Composite Materials Research Articles

Investigation of the Mechanical Properties for Polymer Reinforced by Nanoparticles with Considering Viscoelasticity of the Matrix

Investigation of the Mechanical Properties for Polymer Reinforced by Nanoparticles with Considering Viscoelasticity of the Matrix

Special issue on “Impact and Dynamic Response” in the Journal of Composite Materials

Special issue on “Impact and Dynamic Response” in the <i>Journal of Composite Materials</i>

Indentation-based characterization of creep and hardness behavior of magnesium carbon nanotube nanocomposites at room temperature

The time-dependent plastic deformation response of magnesium/carbon nanotube (CNT) nanocomposites containing 0.25, 0.5, and 0.75 vol% of carbon nanotubes is investigated through depth nanoindentation tests against monolithic pure magnesium in the present study. The Mg-CNT nanocomposite materials were successfully synthesized via a powder metallurgy technique coupled with microwave sintering followed by hot extrusion to produce 8-mm diameter, long solid bars. All depth-sensing indentation creep tests were conducted at ambient (room) temperature employing a diamond Berkovich pyramidal indenter. These tests are dual-stage, i.e., loading to a prescribed peak load of 50 mN, holding the peak load constant for a dwell period of 500 s, and finally unloading. Various strain rates of 0.01, 0.1, 1, and 10 s−1 were performed to assess the effects of strain rate and dwell time on the ambient temperature creep response of the Mg-CNT nanocomposites. The outcomes of these tests are explained through material hardness, microstructure, the extent of CNT content in each material, and strain rate sensitivity. Upon analyzing the nanoindentation creep tests, the dominant creep mechanism at room temperature was found to be a dislocation creep mechanism. It is also found that CNTs increase the creep resistance of magnesium. Findings of this study can be used as a starting point for a high-temperature creep study on Mg-CNT nanocomposites. This paper is a continued study from our group on time-dependent plastic deformation of Mg nanocomposites (i.e., see Haghshenas et al., Journal of Composite Materials, https://doi.org/10.1177/0021998318808358 ). The short-term goal is to provide a compressive picture of the controlling creep mechanisms and their dependency upon, time, temperature, strain rate, volume fraction of the nanoparticles, and the type of the nanoparticles. Mg, in general, is a notorious material for high-temperature application; therefore, the long-term objective is to propose Mg nanocomposite as reliable replacements for Mg when lightweight and creep resistance are needed. However, to be able to confidently suggest such a replacement detailed understanding on the controlling phenomena, mention as short-term goals, are required.

Erratum to “Improvement on Adhesion Properties of Insert Injection Molding Composites: Effect of Inserted Parts, Adhesive Lengths and Injection Conditions” [Open Journal of Composite Materials (2017) 197-206

The original online version of this article (Pinpathomrat, B. and Hamada, H. (2017) Improvement on Adhesion Properties of Insert Injection Molding Composites: Effect of Inserted Parts, Adhesive Lengths and Injection Conditions. Open Journal of Composite Materials, 7, 197-206. https://doi.org/10.4236/ojcm.2017.74013) unfortunately contains several mistakes in Figures 1-4, and Figure 6.

Special Issue on “Impact and Dynamic Response” in Journal of Composite Materials

Special Issue on “Impact and Dynamic Response” in <i>Journal of Composite Materials</i>

Corrigendum

Corrigendum for ‘ Behavior of composite structures orientations towards their failure and damage’ by Abrar H Baluch and CG Kim. Journal of Composite Materials. 2015, Vol. 49(29) 3703–3711 .

A strain energy based failure criterion for nonlinear analysis of composite laminates subjected to triaxial loading

A new strain energy based failure model is developed for fibrous composite laminates under multi-axial loadings, taking into account the effect of hydrostatic stress. A failure mode dependent exponential stiffness reduction model is used to predict material response beyond the initial failure. Predicted mechanical responses and failure envelopes are presented for the 12 benchmark test cases of Part A of the Second World Wide Failure Exercise. The cases cover a wide variety of isotropic, unidirectional and multidirectional laminates under combined in-plane, out-of-plane and triaxial loadings. Both stress–strain curves and the complete failure envelopes were successfully predicted. In some instances, the failure envelopes were open. The predictions together with suitable adjustment of certain parameters are compared with test data in Part B of the Second World Wide Failure Exercise, to be published in Journal of Composite Materials.

Three-dimensional Elasticity Solution for Uniformly Loaded Cross-ply Laminates and Sandwich Plates

This article establishes the bending problem of cross-ply laminated plates using the three-dimensional elasticity equations as well as the technique based on the state space concept. It presents a wide variety of results for the symmetric and antisymmetric analyses of rectangular multilayer plates subjected to a sinusoidally/uniformly distributed load (SDL/UDL). In addition, this study provides a strong mathematical tool allowing one to determine, in an exact and unified manner, the state of stress and displacement of cross-ply laminated composites and sandwich plates. The well-known results (given in Pagano ((1970), Exact Solutions for Rectangular Bidirectional Composites and Sandwich Plates, Journal of Composite Materials, 4(1): 20—24.) and Pagano and Hatfield ((1972), Elastic Behaviour of Multilayered Bidirectional Composites, AIAA Journal, 10(12): 931—933.) due to the exact three-dimensional elasticity solution are in fact special cases of the present technique.

A New Method for Predicting the Fatigue Life of Fiber-reinforced Plastic Laminates

This article introduces a new methodology for predicting the fatigue life of fiber-reinforced plastic (FRP) laminates at various stress levels. This method is based on the evolution of the center of gravity (CG) of the hysteresis loops (HL), and is termed the CG method. The CG method provides precise information regarding the fatigue behavior and damage situation within FRPs, offering highly accurate predictability of fatigue failure. Furthermore, the CG method can be constructed by tests performed on only one specimen by utilizing a new periodic function that represents the response of FRP specimens under dynamic loading fatigue tests - either in displacement control mode or load control mode. The authors originated the CG method in (Momenkhani, K. (2003). Using Geometric Properties of Hysteresis Loops for Predicting Fatigue Damage Accumulation in Fiber Reinforced Plastic Laminates, Doctoral Dissertation, The George Washington University, pp. 49-130), and published it in (Momenkhani, K., Sarkani, S. and Jones, D.L. (2005). Development and Application of a Model Using Center of Gravity of Hysteresis Loops to Predict Fatigue Damage Accumulation in Fiber Reinforced Plastic Laminates, Journal of Composite Materials, 39(6): 557-575). The present article applies the CG method as an alternative model to replace and supersede S-N curve methods for fatigue life predictions of FRPs.

Damping Analysis of Unidirectional Glass Fiber Composites with Interleaved Viscoelastic Layers: Experimental Investigation and Discussion

The article investigates the damping of unidirectional glass fiber composites with a single or two interleaved viscoelastic layers. The experimental damping characteristics are derived from flexural vibrations of cantilever beams as a function of the fiber orientation. The experimental results are analyzed considering the modeling developed in a previous article, Berthelot, J.-M. Damping Analysis of Orthotropic Composites with Interleaved Viscoelastic Layers Modelling, Journal of Composite Materials (in press). The analysis considers the variations of Young’s modulus and damping of viscoelastic layers with the frequency. Finally, the article presents the effects of Young’s modulus and the damping of a viscoelastic layer interleaved in the middle plane of unidirectional laminate. The results are also reported for the case of external viscoelastic layers.

Nonlinear Response of the Macro Fiber Composite Actuator to Monotonically Increasing Excitation Voltage

A nonlinear model for a piezoelectric continuum subjected to a monotonic increase in electric field under constant mechanical load is investigated. A general model is derived and then specialized for a piezoceramic-based material with anisotropic actuation and mechanical properties, for example, the Macro Fiber Composite (MFC) actuator. This formulation includes the linear-elastic mechanical response, as well as linear and second-order piezoelectric behavior and a second-order electromechanical cross-term. Using previously published work by the same authors (Williams, R.B., Inman, D.J. and Wilkie, W.K. 2004. “Tensile and Shear Behavior of Macro Fiber Composite Actuators,” Journal of Composite Materials, 38(10):855—870) dealing with the mechanical response of the MFC, this set of material properties is determined experimentally in order to characterize the response of this device to given external loading conditions.

Dynamic Response of Sandwich Plates to Medium-velocity Impact

Overall and local deflections of a single span of a continuous sandwich plate are evaluated under local contacts with a rigid indenter, at relative velocities of 10 and 20 m/s (20-40 knots), to simulate the effect of impacts that can be applied to ship sandwich structures by floating objects or moorings. Laminated carbon-vinyl ester face sheets and a H100 PVC foam core, possibly separated from the impacted face sheet by a stiff and ductile polyurethane (PUR) interlayer, comprise the sandwich plate. As in our previous study of the effect of quasi-static contacts (Suvorov, A.P. and Dvorak, G.J. (2005). Protection of Sandwich Plates from Low Velocity Impact, Journal of Composite Materials (to appear)), the focus is on the evaluation of contact forces and deflections of the face sheet and foam core interface, and on the membrane or in-plane strains in the face sheet at the contact point. These quantities are well-known potential sources of damage, causing core crushing, and face sheet delamination and/or penetration. As expected, the results show that the magnitudes of these quantities depend on both the distance of the contact point from the nearest support, and on the initial velocity of the indenter of a given mass. Both local face sheet deflections and core interface indentations are high if the impact point is within a distance from a support that is equal to 2-3 times the total sandwich plate thickness; significantly lower values are found at more distant contact points. These deflections are much reduced by replacing the foam core with an aluminum honeycomb in the supported region of the plate. However, this reinforcement elevates both the contact force and the in-plane strain in the face sheet. Therefore, thickening of the exposed face sheets should be considered around supports. Most of the kinetic energy is absorbed by the core, hence addition of the stiff and ductile PUR interlayer does not have as much effect on the results as it had in quasi-static contact.

Injection Pultrusion Simulation for Polyester/Glass Mat/Rovings/Mat Composites

Producing quality pultruded parts requires that complete wet out of the reinforcement fibers is achieved in the injection chamber. The magnitude of the injection pressure is extremely important for achieving good wet out of the fibers. This work focused on the impact of pull speed, resin viscosity, and product thickness on resin fiber wet out in the injection chamber for a polyester resin (mat/roving/mat) composite. Recommended injection pressures for complete wet out are predicted for given sets of processing parameters for polyester/glass fiber (mat/rovings/mat) composites. Flow through porous media (Darcy’s law) is employed to model the fiber/resin system of injection pultrusion. The governing equations are solved, by using the finite volume method, to predict the resin pressure, resin velocity field, and resin moving flow front location. The Gutowski (Gutowski, T.G., Morigaki, T. and Cai, Z. (1987). The Consolidation of Laminate Composites, Journal of Composite Materials. 21(7): 172-187) permeability model is used to determine the permeability in the roving layer and the Kozeny-Carman (Carman, P.C. (1939). Flow through Granular Beds, Trans. Int. Chem. Eng., 15: 150-166) model is used to predict the permeability in the mat layers.

Residual Compressive Failure Characteristics of Hybrid Composites with Nonwoven Carbon Tissue after Indentation Damage

The purpose of this study is to investigate the relationship between the low-energy impact damages under static indentation loadings and the residual compressive static and fatigue strengths after damage in hybrid composites with nonwoven carbon tissue (NWCT). The hybrid laminates are made by interleaving the NWCT layer between the CFRP layer interfaces. The indentation damages were discussed by investigating the delamination areas and the indentation energies of four kinds of angle-ply laminates ([455/ 455/455] and [453/ 453/453/ 453/453] CFRP laminates, and [455// 455//455] and [453// 453//453// 453//453] hybrid laminates; the symbol “//” means that the NWCT layer is located at an interface between the CFRP layers. The delamination areas of the hybrid laminates were reduced to about half of the CFRP’s by the indentation loading (Lee, S.H., Aono, Y., Noguchi, H. and Cheong, S.K. (2003). Damage Mechanism of Hybrid Composites with Non-Woven Carbon Tissue Subjected to Quasi-Static Indentation Loads, Journal of Composite Materials, 37: 333–349). After the indentation damage, compressive static and fatigue tests are carried out using an anti-buckling guide for the angle-ply laminates. The failure modes of the angle-ply CFRP and hybrid specimens are caused by global buckling under the compressive static loading. However, the failure modes of the angle-ply CFRP and hybrid specimens at Nf &lt;10 6cycles are caused by shearing the damaged part under the compression–compression fatigue loading. Compared with CFRP laminates, compressive fatigue lives of the hybrid laminates were significantly extended in all the stress ranges. The NWCT interleaving effect is examined based on the observations of the damage in the hybrid specimens after the indentation damage. Also, the compressive static and fatigue failure processes are discussed from the observation of the fracture surfaces of damaged parts and failed appearance of specimens when subjected to the compressive loadings after the indentation damage.

A Burr Type X Chain-of-Links Model for Carbon Fibers

A model for application to carbon fibrous composites is proposed based on the Burr type X (BurrX) distribution first proposed by Burr (Burr, I.W. (1942). Annals of Mathematical Statistics, 13: 215-222) with an included parameter to account for fiber length. The model is further generalized similar to the generalization of the Weibull proposed by Padgett et al. (Padgett, W.J., Durham, S.D. and Mason, A.M. (1995). Journal of Composite Materials, 29: 1873-1884). Maximum likelihood estimation is briefly discussed, and the model is applied to the single-filament data of Bader and Priest (Bader, M.G. and Priest, A.M. (1982). In: Hayashi, T., Kawata, K. and Umekawa, S. (eds), Progress in Science and Engineering of Composites, pp. 1129-1136. ICCM-IV, Tokyo).

Numerical Simulation of Pressure Variation and Resin Flow in Injection Pultrusion

Injection pultrusion is a continuous process for manufacturing composite materials. To produce good quality parts it is essential that complete wet out of the reinforcement fibers is achieved in the injection chamber. To achieve good wet out of the fibers, the magnitude of the resin injection pressure is extremely important. The present study is focused on the effects of pull speed, fiber volume fraction, resin viscosity and compression ratio (taper) of the injection chamber on resin fiber wet out within the injection chamber for polyester-glass roving composites. The recommended injection pressures for complete wet out are predicted for a wide and comprehensive variety of processing variables; this work is novel in that it has new and comprehensive results not available in the existing literature. Darcy's law is used to model the fiber/resin system of injection pultrusion. The Gutowski [Gutowski, T.G., Morigaki, T. and Cai, Z. (1987). The Consolidation of Laminate Composites, Journal of Composite Materials, 21(7): 172-187.] permeability model is used to determine the transverse permeability and the Kozeny-Carman [Carman, P.C. (1939). Flow Through Granular Beds, Trans. Int. Chem. Eng., 15: 150-166.] model is used to predict the longitudinal permeability. The finite volume method is used to predict the resin pressure field, resin velocity field, and resin moving flow front location.

Triaxial Woven Fabric (TWF) Composites with Open Holes (Part II): Verification of the Finite Element Models

An elaborate finite element formulation was developed for the triaxial woven fabric (TWF) composites and this is presented in a parallel publication [Zhao, Q. and Hoa, S.V. Triaxial Woven Fabric (TWF) Composites With Open Holes (Part I): Finite Element Models For Analysis, Accepted, Journal of Composite Materials, this same issue.]. This paper presents examples using the finite elements developed and experimental work to obtain results for comparison purposes. One example deals with the TWF specimens subjected to loading along an axial yarn direction. The other example deals with other TWF specimens subjected to loading transverse to the axial yarn direction. Effects of the width and length of the sample are examined. Noncontact laser extensometer method is used for the deformation measurement. The significance and meaning of the results are discussed.

Modeling of 3D Angle Interlock Woven Fabric Composites

A three dimensional micromechanical modeling approach was previously developed for predicting elastic constants of 2D woven fabric composites [Sheng, S.Z. and Hoa, S.V. (2001). Three dimensional micromechanical modeling of woven fabric composites. Journal of Composite Materials, 35(19): 1701-1729.]. In this paper, the approach is extended for predicting elastic constants of 3D angle interlock woven fabric composites. The micro fabric geometry of general 3D woven composites is described by using a three dimensional geometric model first. Then a variational potential method is proposed to obtain the continuous integration transformation of the three-dimensional stiffness and compliance matrices associated with the micro fabric geometry for 3D woven fabric composites. Finally, elastic constants are obtained by using the method based on the fabric geometry for several 3D angle interlock woven fabric composites. Good agreement is shown between the present predicted results and experimental results available in the literature.

Simulations and Experiments on Low-Pressure Permeation of Fabrics: Part II—The Variable Gap Model and Prediction of Permeability

Use of the creeping flow assumption provides a computationally efficient and accurate means of predicting flow fronts in reinforcement media in many technologically important polymer processes. In the case of fabrics, this creeping flow is shown to proceed primarily through the gaps in fabrics, with capillarity playing little if any role for commonly used materials. This finding has important implications for selection of strategy in modeling manufacturing processes of such materials. Namely, in the presence of fabric deformation which induces local shear, changes in the gap architecture greatly affect the flow patterns, and are not well predicted by tensor transformation of Darcy-type permeabilities. Asimple, classic flow model is adapted to the case of fabrics penetrated by low-pressure viscous liquids after careful analysis of fabric architecture. An applicability range of this creeping flow model, the variable gap model, is developed. The present paper gives the model assumptions, and confirmation of its agreement with more sophisticated calculations. A demonstration of the approach for an unbalanced fabric (Knytex 24 5×4 unbalanced plain-woven glass fabric) shows excellent prediction of the bounds on flow behavior, and supports our earlier experimental findings on flow front orientation. This approach also shows clear superiority to semi-empirical, geometry-based models, since no fitting parameters at all are used in the modeling: only the constituent materials’ geometry and properties are needed. This methodology is better able to predict trends in flow fronts, both qualitatively and quantitatively, than semi-empirical fitting. Extension of this work to realistic production processes is planned. 1Author to whom correspondence should be addressed. 1285 Journal ofCOMPOSITE MATERIALS, Vol. 35, No. 14/2001

The energetics of heterogeneous deformation in open-cell solid foams

Compressed open–cell solid foams frequently exhibit spatially heterogeneous distributions of local stretch. The theoretical aspects of this deformation habit have not been clearly elucidated. Here we propose a simple nonlinear model aimed at illustrating the most salient features of the micromechanics of uniaxially stretched solid foams. Then we study the energetics of the model to show that the stretch heterogeneity observed in experiments stems from the lack of convexity of the governing energy functional, which favours two characteristic values of local stretch. These characteristic values are independent of the applied overall stretch and define two configurational phases of the foam. The predicted stretch distributions correspond to stratified mixtures of the phases; stretching occurs in the form of a phase transformation, by growth of one of the phases at the expense of the other. We also compare the predicted mechanical response with experimental data for a series of foams of different densities and discuss the analogy between the stretching of foams and the liquefaction of van der Waals gases. Lastly, we perform displacement field measurements using the digital image correlation technique and find the results to be in agreement with our predictions.