Showing papers in "Journal of Thermoplastic Composite Materials in 2004"
TL;DR: A review of different fusion-bonding methods for thermoplastic composite components and present recent developments in this area is presented in this article, where various welding techniques and corresponding manufacturing methodologies, the required equipment, the effects of processing parameters on weld performance and quality, the advantages/disadvantages of each technique, and the applications are described.
Abstract: Joining of thermoplastic composites is an important step in the manufacturing of aerospace thermoplastic composite structures. Therefore, several joining methods for thermoplastic composite components have been under investigation and development. In general, joining of thermoplastic composites can be categorized into mechanical fastening, adhesive bonding, solvent bonding, co-consolidation, and fusion bonding or welding. Fusion bonding or welding has great potential for the joining, assembly, and repair of thermoplastic composite components and also offers many advantages over other joining techniques. The process of fusion-bonding involves heating and melting the polymer on the bond surfaces of the components and then pressing these surfaces together for polymer solidification and consolidation. The focus of this paper is to review the different fusion-bonding methods for thermoplastic composite components and present recent developments in this area. The various welding techniques and the corresponding manufacturing methodologies, the required equipment, the effects of processing parameters on weld performance and quality, the advantages/disadvantages of each technique, and the applications are described.
396 citations
TL;DR: In this article, the effect of mixing ratio and the types and concentrations of coupling agents on the physical and mechanical properties of paper sludge-thermoplastic polymer composites was investigated.
Abstract: This study investigates the effect of paper sludge’s mixing ratio and the types and concentrations of coupling agents on the physical and mechanical properties of paper sludge-thermoplastic polymer composites. In the experiment, four levels of mixing ratios of paper sludge to thermoplastic polymer (10: 90, 20: 80, 30: 70 and 40: 60) and three levels of coupling agent (Epolene G-3003TM) content (1, 3, and 5 wt.%) were designed to discuss the physical and mechanical properties of composite. Composite density, as expected, increased but melt flow index decreased when the paper sludge content increased. Thickness swelling and water absorption of composites was slightly improved by the addition of paper sludge compared with control specimens. Tensile properties of composites significantly increased as the mixing ratio of paper sludge increased. Especially, tensile modulus improved with the increase of paper sludge content. Flexural strength and modulus showed similar trends to that of the tensile properties. N...
57 citations
TL;DR: In this paper, four new ways to think about joining composites are proposed, and a possibility for each approach is presented to provoke thinking among design and process engineers, and the new paradigm of joining being a pragmatic process performed as a last step in manufacture is challenged, and it must increasingly become an enabling technology that is integrated with material and structure synthesis.
Abstract: Custom-engineered functionally-specific properties leading to greatly enhanced design versatility have drawn designers to composites, but will make these materials-of-preference only if better ways can be found for producing better joints. The very micro- and macrostructure that gives rise to the unparalleled properties possible with composites exacerbates the inherent weaknesses virtually always associated with joints. Prevailing methods of mechanical fastening and adhesive or thermal bonding (welding) are nonoptimal, if not inappropriate, extensions of methods used for joining conventional metallic or polymeric structures with little real change in over two millennia. This paper challenges the old paradigm of joining being a pragmatic process performed as a last step in manufacture and proposes that it must increasingly become an enabling technology that is integrated with material and structure synthesis. Four new ways to think about joining composites are proposed, and a possibility for each approach is presented to provoke thinking among design and process engineers.
49 citations
TL;DR: The results of interlaminar and tool-laminate shear tests performed on a twill 2 2 PP/glass fabric are described in this paper, where the influence of the laminate temperature, pullout velocity and normal pressure on the inter-laminar shear stress and friction coefficient are evaluated.
Abstract: The results of interlaminar and tool–laminate shear tests performed on a twill 2 2 PP/glass fabric are described in this paper. The influence of the laminate temperature, pullout velocity and normal pressure on the interlaminar shear stress and friction coefficient are evaluated, as well as the effect of cooling the specimen from the melt to simulate real forming conditions. Opposite trends were observed for the variation of the shear stress and friction coefficient whether the tests were performed above the melt temperature of the matrix or above the crystallization temperature (135, 140, and 155 after cooling from the melt temperature. For the interlaminar shear tests, this was caused by the shift from an interlaminar to an intralaminar shear deformation mode occurring. For the tool–laminate shear tests, this was caused by the shift from matrix shear at the interface tool–laminate to direct Coulomb friction of the fibers with the tool with an increase of the normal pressure and/or an increase of the mat...
42 citations
TL;DR: In this article, the impact and tensile properties of expanded wood fiber polystyrene composites (EPSC) made with a physical blowing agent were investigated based on a statistical experimental design.
Abstract: In this study, processing–structure–mechanical properties relationships in expanded wood fiber polystyrene composites (EPSC) made with a physical blowing agent were investigated. A systematic investigation was performed based on a statistical experimental design. The samples were saturated with carbon dioxide at high pressure and ambient temperature and the saturated specimens were expanded at elevated temperatures. The relations between impact and tensile properties of EPSC and foaming process and structure were studied. Fiber content was found to be the most important parameter controlling impact strength and tensile modulus. The impact strength of EPSC was increased about three times when the fiber content increased to 20%. Using the Halpin–Tsai equation, a model was developed to relate tensile modulus to the density of EPSC.
39 citations
TL;DR: In this article, Wood-plastic composites (WPCs) have been proposed as an alternative to treated timber due to the high environmental damage caused by treated lumber, and the use of treated lumber to reduce environmental damage.
Abstract: Current timber waterfront structures require the use of treated lumber to reduce environmental damage. Wood–plastic composites (WPCs) have been proposed as an alternative to treated timber due to t...
34 citations
TL;DR: In this article, a regression model was constructed to optimize the relationship between the void fraction of foamed HDPE/wood-flour composites, the processing conditions (extruder's die temperature and screw speed rate), and the formulation compositions [chemical foaming agent (CFA) concentration and the moisture content of wood flour] by applying a four-factor central composite design (CCD) statistical approach.
Abstract: In this paper, a regression model was constructed to optimize the relationships between the void fraction of foamed HDPE/wood-flour composites, the processing conditions (extruder’s die temperature and screw speed rate), and the formulation compositions [chemical foaming agent (CFA) concentration and the moisture content of wood flour] by applying a four-factor central composite design (CCD) statistical approach Design Expert software was employed to carry out the experimental design, statistical analysis, and numerical optimization The analysis of variance (ANOVA) of the model showed that the void fraction of HDPE/wood-flour composites was a strong function of the extruder’s die temperature, the screw speed rate, and the moisture content of wood flour, while independent of the CFA content within the studied range (0 1%) In addition, the moisture content of wood flour and the extruder’s screw speed rate exhibited significant interaction effect on the void fraction of the foamed composites The response
31 citations
TL;DR: In this article, the efficiency of different melt impregnation methods for producing continuous glass fiber-polypropylene tapes has been evaluated, and the selected methods were the common pin assisted method, a crosshead impregnation die including different vibration techniques and a slit die.
Abstract: The efficiency of different melt impregnation methods for producing continuous glass fiber–polypropylene tapes has been evaluated. The selected methods were the common pin assisted method, a crosshead impregnation die including different vibration techniques and a slit die. The degree of melt impregnation was studied qualitatively with optical microscopy and determined quantitatively by opacity measurements. Excellent results were obtained using the radial slit die, followed by the pin chamber impregnation method. The crosshead impregnation die gave poor impregnation. With the radial slit die it was possible to achieve high fiber volume fraction and it was easy to control the fiber–matrix content. The haul off speed ranged from 1–10 m/min.
27 citations
TL;DR: In this article, an integrated sandwich composite adopting 3D woven fabrics as the core material was experimentally characterized for its effective elastic modulus as well as its capacity of receivable.
Abstract: In this article, an integrated sandwich composite adopting 3D woven fabrics as the core material was experimentally characterized for its effective elastic modulus as well as its capacity of receiv...
26 citations
TL;DR: In this article, equal channel angular extrusion (ECAE) was used to obtain a log logistic distribution with a mean fiber angle of 23.5 degrees and 20.8 degrees for one and two passes respectively.
Abstract: Glass-fiber/polyacetal cylindrical rods prepared by conventional compounding and extrusion were processed by equal channel angular extrusion (ECAE). The initial material contained 109.8mm long fibers with uniformly distributed fiber angle orientations between 11.8 and 56.0 � . One extrusion pass with a soft matrix at 73 � C directed the fibers to a loglogistic distribution with a mean orientation angle of 23.5 � . ECAE at room temperature did this with mean fiber angles becoming 20.8 and 23.6 � for one and two passes respectively. The interquartile range of the angles narrowed with reduced processing temperature and number of processing passes.
23 citations
TL;DR: In this paper, the use of a counteracting pressure can be beneficial during the forming of fiber-reinforced thermoplastic sheets more specifically; this paper addresses the experimental setup that was developed and built to conduct small experiments.
Abstract: The stamp thermo-hydroforming process involves supporting the thermoplastic sheet with a bed of heated viscous fluid that applies a hydrostatic pressure across the part throughout the forming process. This hydrostatic pressure produces a through-thickness compressive stress that delays the onset of delamination, reduces the formation of wrinkles due to frictional traction forces, and results in better-formed parts. The overall goal of this research is to verify, through experimentation and numerical modeling, that the stamp thermo-hydroforming process provides a suitable alternative to conventional thermoforming methods, such as bag molding and stamp forming, as a means for processing glass-mat fiber-reinforced thermoplastic materials. The goal of this paper is to solely address whether the use of a counteracting pressure can be beneficial during the forming of fiber-reinforced thermoplastic sheets more specifically; this paper addresses the experimental setup that was developed and built to conduct small...
TL;DR: In this article, a laminate with unidirectional (UD) fiber orientation of three different commingled yarns, comprising polyamide-12 and poly(butylene-terephthalate) fibers blended with stretch broken carbon fibers (CF), were produced at different processing conditions, by means of void content measurement, mechanical testing along and transverse to the fiber direction, and optical microscopy.
Abstract: Laminates with unidirectional (UD) fiber orientation of three different commingled yarns, comprising poly(amide-12) and poly(butylene-terephthalate) fibers blended with stretch broken carbon fibers (CF), were produced at different processing conditions. The achieved laminate quality was evaluated by means of void content measurement, mechanical testing along and transverse to the fiber direction, and optical microscopy. It was found that - under the investigated processing conditions - the cooling/consolidation time is not sufficiently long to obtain laminates with satisfactorily low void content, unless a commingled yarn with exceptionally intimate blending quality is employed. Incomplete fiber impregnation resulted in a drastic decrease of transverse tensile strength as compared with values obtained for compression-molded reference laminates. Stamp forming of carbon and poly(butylene-terephthalate) fiber commingled yarn with extraordinary degree of commingling delivered laminates with as low void conten...
TL;DR: In this article, the development of new technologies to fabricate long and continuous-fiber-reinforced composite structures from low-cost thermoplastic matrix semiproducts was reported.
Abstract: The present work reports the development of new technologies to fabricate long and continuous-fiber-reinforced composite structures from low-cost thermoplastic matrix semiproducts. These semiproducts, thermoplastic matrix towpregs and preconsolidated tapes (PCTs), were produced in a purposely-built prototype machine, by deposition of a thermoplastic polymer in powder form on continuous fibers. The work also presents the advances made in the processing of these materials into composites by conventional techniques, such as pultrusion, filament winding and compression molding. Finally, it describes the investigation of the optimal processing conditions that maximize the mechanical properties of the composites. These properties are good enough for the composites to be used as engineering materials in many structural applications.
TL;DR: In this paper, the influence of electron beam irradiation on the elasticity and stress-strain curve of composite materials reinforced by carbon fiber (CF), carbon fiber-reinforced polyme...
Abstract: In order to evaluate the influence of electron beam (EB) irradiation on the elasticity and stress–strain curve of composite materials reinforced by carbon fiber (CF), carbon fiber-reinforced polyme...
TL;DR: In this paper, the thermal stress analysis of an adhesively bonded tee joint with double support made of unidirectional carbon fiber reinforced plastics (CFRP) was carried out for variable thermal loading conditions along its outer boundaries and different plate edge conditions.
Abstract: Carbon fiber reinforced plastics (CFRP) can be successfully joined to metal or composite structural components using the adhesive bonding technique [Semerdjiev, S. (1970). Metal to Metal Adhesive Bonding, Business Books Ltd., London.]. The stress and deformation fields occurring in the adhesive joints due to the thermal loads as well as the structural loads play an important role on the joint strength since the thermal and mechanical properties of the adhesive and adherends are different. Previous thermal stress analyses of the adhesive single-lap joints with simple geometries assumed a uniform temperature distribution through the adhesive joint, consequently predicted uniform thermal strain and stress distributions. In this study, the thermal stress analysis of an adhesively bonded tee joint with double support made of unidirectional CFRP was carried out for variable thermal loading conditions along its outer boundaries and different plate edge conditions. The large displacement and rotation effects were...
TL;DR: In this article, an investigation of tape layup process of a thermoplastic composite (APC-2) using a nitrogen torch is conducted, where the heat transfer coefficient along the surfaces of the composite is estimated via a three-dimensional flow analysis, and the surface temperature of composite is obtained through a two-dimensional heat conduction analysis using the finite element method (FEM).
Abstract: An investigation of tape layup process of a thermoplastic composite (APC-2) using a nitrogen torch is conducted. The distribution of heat transfer coefficient along the surfaces of the composite is estimated via a three-dimensional flow analysis, and the surface temperature of the composite is obtained through a two-dimensional heat conduction analysis using the finite element method (FEM). The heat transfer coefficient and the surface temperature are so interrelated that it poses a conjugate heat transfer problem. Thus, the heat transfer coefficient and the surface temperature of the composite are sought simultaneously in an iterative fashion. The computational results are presented for a specific case.
TL;DR: In this paper, a 3D model for the simulation of the thermoplastic pultrusion process is developed based on the Finite Element-Nodal Control Volume (FE-NCV) approach.
Abstract: A three-dimensional (3D) model for the simulation of the thermoplastic pultrusion process is developed. The simulation procedure and algorithms are based on the Finite Element–Nodal Control Volume (FE–NCV) approach. For illustration purposes, APC-2 CF–PEEK is used as a candidate material along with multiheater steel die assemblies. Heat transfer in the die and the composite is modeled using FEs whereas NCVs are used to model crystallization kinetics and heat of reaction for PEEK. The developed simulation procedure is validated using available data. Subsequently, versatility of the model for simulating various types of die assembly and transient heat transfer effects on crystallization is demonstrated.
TL;DR: In this article, binary and ternary composite materials, based on a low-density polyethylene, metal alloy, which have a melting point close to those of polyethylenes and carbon black, were presented.
Abstract: This work presents the novel binary and ternary composite materials, based on a low-density polyethylene, metal alloy, which have a melting point close to those of polyethylene and carbon black. Oriented structures were obtained when high-viscosity polyethylene was used as a matrix material. Resistivity of the composite was investigated and nonohmic behavior of the ternary composites was revealed. Temperature dependence of the thermal capacity was studied. The IR (infrared) spectra of the composites were studied using an FTIR (Fourier-transform infrared) spectrophotometer. The presence of the alloy caused intensive oxidation of carbon black in the ternary composites as well.
TL;DR: In this paper, the effects of the strip vertical or horizontal delamination width on the buckling loads of the simply supported woven steel-reinforced thermoplastic (LDFE, F.2.12) laminated composite plates of four layers have been investigated.
Abstract: In this study, the effects of the strip vertical or horizontal delamination width on the buckling loads of the simply supported woven steel-reinforced thermoplastic (LDFE, F.2.12) laminated composite plates of four layers have been investigated. Three-dimensional finite element models of the square laminated plates have been established. There are two different delamination shapes, between second and third layers in each of these models. The stacking sequences are chosen as [0]4, [15°/-15°]s, [15°/-15°]2, [30°/-30°]s, [30°/-30°]2, [45°]4, and [45°/-45°]s. Firstly the harmony between theoretical and finite element solutions’ results of the plate without delamination has been shown. Then, the buckling loads have been determined for each models having different delamination width. The results show that important decreases in the buckling loads occur after a certain value of the delamination width. The changing ratios of the results of the symmetric or antisymmetric cases are approximately the same for each a...
TL;DR: In this paper, the overall elastic and viscoelastic properties of particulate composites with graded interphase have been analyzed analytically and the effective storage and loss moduli of the composite were also determined through the dynamic correspondence principle.
Abstract: The overall elastic and viscoelastic properties of particulate composites with graded interphase have been analyzed analytically. The localization relation for a coated particle with a graded interphase in the radial direction has been firstly derived, and the effective elastic moduli of such composites are then estimated by the mean field theory and generalized self-consistent method respectively. The effective storage and loss moduli of the composite are also determined through the dynamic correspondence principle. The results show that the nature of the interphase (soft and hard) can have important influence on the prediction for effective elastic and viscoelastic properties of the composite, especially for a soft graded interphase, the predictions based on a uniform interphase model overestimates largely the effective elastic and viscoelastic moduli of the composite.
TL;DR: In this article, thermal elastic-plastic stress analysis is carried out on simply supported symmetric cross-ply and angle-ply thermoplastic laminated plates under various temperature change through the thickness of plates.
Abstract: In this paper, thermal elastic-plastic stress analysis is carried out on simply supported symmetric cross-ply [0°/90°]2 and angle-ply [15°/-15°]2, [30°/-30°]2,[45°/-45°]2,[60°/-60°]2 thermoplastic laminated plates under various temperature change through the thickness of plates. The plates are composed of four orthotropic layers bonded symmetrically. In the solution, a special computer program has been employed. The composite materials are assumed to be strain hardening. The Tsai-Hill Theory is used as a yield criterion. Residual stresses are determined in the symmetric cross-ply and angle-ply laminated plates for small deformations. The intensity of stress components in the symmetric cross-ply laminated plate is higher than in angle-ply laminated plate due to the differences among the stiffnesses of layers. Plastic yielding occurs in all the laminated plate at the same temperature.
TL;DR: In this article, several parameters affecting the lap shear strength of vibration-welded joints of continuous-fiber-reinforced thermoplastic matrix composites have been experimentally investigated.
Abstract: In this paper, we discuss vibration welding of continuous-fiberreinforced thermoplastic matrix composites. Several parameters affecting the lap shear strength of vibration-welded joints of glass and carbon fiber-reinforced polypropylene and polyamide-6 matrix composites have been experimentally investigated. These parameters were clamping pressure, vibration time, vibration direction, and holding time. Weld strength at elevated temperatures was also investigated. The results showed that the combination of clamping pressure and vibration time had a significant effect on the lap shear strength. Holding time also influenced lap shear strength, but the effect of vibration direction was not significant. In addition to lap shear specimens, ring specimens were designed and tested to determine the crosstension strength of these composites under tensile stress normal to the weld plane.
TL;DR: In this paper, a thermoplastic polyester powder binder is attached to a fabric during the preforming stage, and the powder is sprinkled onto the glass fabric and melted by use of heat and pressure, to form the separation layer.
Abstract: Coinjection resin transfer molding (CIRTM) requires an impermeable barrier layer to prevent undesired mixing of resins injected into the mold. This study involves in situ formation of this barrier layer using a thermoplastic polyester powder binder attached to a fabric during the preforming stage. The powder binder is sprinkled onto the glass fabric and melted by use of heat and pressure, to form the separation layer. A number of factors such as preforming temperature, pressure and time that govern the spread of individual binder particles into a film and the subsequent impregnation into the fabric are evaluated. Lateral spread of particles on nonporous substrate is studied and verified. A series of models are used to predict the impregnation of the binder melt into the fabric at the given preforming conditions. The optimized preforming conditions for impermeable film formation were determined for a biaxial weave fabric. Coinjected laminates using the in situ barrier layer were manufactured and their perf...
TL;DR: In this article, smart glass fiber-reinforced polymer (FRP) reinforcements with embedded Fabry-Perot fiber-optic sensors are pultruded and investigated in both laboratory and environmental extreme conditions.
Abstract: Smart glass fiber-reinforced polymer (FRP) reinforcements with embedded Fabry–Perot fiber-optic sensors are pultruded and investigated in both laboratory and environmental extreme conditions. Various mechanical (quasi-static and cyclic loads, fatigue loads, long-and short-term creep), thermal (from -40 to +60° C), and severe environmental (alkaline solutions with pH12.8) loads are imposed onto the smart FRP tendons, prior to their application in laboratorydesigned concrete beams. A comprehensive testing program is followed for the beams, including thermal exposure during and after concrete curing phases, static and cyclic failure-induced loadings. In all testing programs, the data obtained from the interferometric Fabry–Perot fiber-optic sensors are compared to those from an extensometer, an electrical resistance strain gage, and an LVDT. The study shows that the response, in terms of internal mechanical strain, against applied mechanical and structural loads up to the failure of the concrete beams can be...
TL;DR: In this paper, the authors carried out elastic-plastic stress analysis on steel fiber reinforced thermoplastic matrix laminated beams loaded by bending moment and found that the residual stress component was highest at the upper and lower surfaces.
Abstract: Elastic–plastic stress analysis is carried out on steel fiber reinforced thermoplastic matrix laminated beams loaded by bending moment. The beam is composed of four orthotropic layers, perfectly bonded and symmetrically arranged with respect to the x-axis. The orientation angles are chosen as (90°/0°)s, (30°/30°)s, (45°/45°)s and (60°/60°)s. The composite material is assumed to be linearly hardening. x residual stress component is found to be highest at the upper and lower surfaces. However, when the applied bending moment is increased, the plastic region is further expanded towards middle plane from the upper and lower surfaces of the beam and so x residual stress component is found to be highest at the elastic and plastic boundaries. The plastic flow is obtained to be maximum at the upper and lower surfaces for (30°/30°)s orientation. The transverse displacement is obtained to be highest at the free end for (90°/0°)s orientation.
TL;DR: In this article, some expressions for describing relationships between die-swell ratio, melt shear modulus, and exit-pressure drop during flow of viscoelastic fluids in a long circular die are proposed.
Abstract: Obvious viscoelastic phenomena, such as die-swell and exit-pressure losses, appear when a viscoelastic fluid leaves a die. It is generally believed that the die-swell ratio (B), the melt shear modulus (G), and the exit-pressure drop (ΔPex) are important parameters for the characterization of the elastic behavior of viscoelastic fluids during die flow. There may be, therefore, some interrelations between them. In the present article, relationships among G, B, and ΔPex are discussed. On the basis of previous work, some expressions for describing relationships between B and G, ΔPex, and B, as well as ΔPex and G during flow of viscoelastic fluids in a long circular die are proposed. The values of G are estimated from the measured B during extrusion of a carbon black and calcium carbonate-filled rubber compound, and predictions of G by using the measured data of ΔPex are compared with its calculations from the B data during capillary extrusion of a high-density polyethylene (HDPE) melt. The results showed that...
TL;DR: In this article, the dielectric properties of three sets of composites are considered, namely, aramid fiber-reinforced nylon 66, fiber reinforced poly(ether ether ketone), and ultrahigh molecular weight fiber-resinforced high-density polyethylene.
Abstract: Transcrystallization, characterized by dense nucleation on the fiber surface and constrained radial crystalline growth, results in different crystalline morphology than that of the bulk. Concomitantly, it results in redistribution of the amorphous phase, generating rearrangement of the phase transition pattern. This can be identified by dynamic energy dissipation techniques such as highsensitivity dielectric spectroscopy performed in this study. Focusing on the glass transition, the dielectric properties of three sets of composites are considered, namely, aramid fiber-reinforced nylon 66, aramid fiber-reinforced poly(ether ether ketone), and ultrahigh molecular weight fiber-reinforced high-density polyethylene. This study demonstrates that dielectric spectroscopy is a unique experimental tool, highly sensitive to the presence of transcrystallinity via its effect on amorphous phase redistribution. Its sensitivity is reflected by a range of dielectric parameters, namely, the activation energy, the dielectri...