The Experts below are selected from a list of 2601 Experts worldwide ranked by ideXlab platform
M. Hou - One of the best experts on this subject based on the ideXlab platform.
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On stamp forming of curved and flexible geometry components from Continuous Glass Fiber/polypropylene composites
Composites Part A: Applied Science and Manufacturing, 1998Co-Authors: K. Friedrich, M. HouAbstract:Abstract A thermoforming technique known as stamp forming has been used to transform a pre-consolidated unidirectional Glass Fiber reinforced polypropylene (GF/PP) flat panel into a more complex geometry. To achieve this, firstly, two-dimensional half-tube composite parts were formed, mainly to optimize the processing conditions such as stamping temperature, forming velocity and mold geometry. The two-dimensional mold was kept at room temperature, whereas the composite panel to be formed was raised to a certain preheating temperature. The preconsolidated GF/PP panel, heated by contact heating in an external heater above the melting temperature of PP matrix, was then formed in the cold metal mold. Typical cycle times (including preheating and stamping) were in the range of 3–4 min. Secondly, a novel rod-bed mold was designed to manufacture three-dimensional parts using the same forming technique. Both halves of the mold were made of several tiny round metal rods in a metal frame. This rod-bed mold allowed to duplicate any solid contour by pushing it slightly on to the spring loaded rods. The final position of these rods could be fixed by forcing the side plates of the metal frame together. As an example, a saddle shaped, three-dimensional contour could be fairly well reproduced by stamp forming GF/PP composites with this rod-bed mold. The latter can have enormous potential in the manufacturing of medical devices such as adjustable prostheses or splints where only a limited number of parts with complex geometry have to be formed.
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on stamp forming of curved and flexible geometry components from Continuous Glass Fiber polypropylene composites
Composites Part A-applied Science and Manufacturing, 1998Co-Authors: K. Friedrich, M. HouAbstract:Abstract A thermoforming technique known as stamp forming has been used to transform a pre-consolidated unidirectional Glass Fiber reinforced polypropylene (GF/PP) flat panel into a more complex geometry. To achieve this, firstly, two-dimensional half-tube composite parts were formed, mainly to optimize the processing conditions such as stamping temperature, forming velocity and mold geometry. The two-dimensional mold was kept at room temperature, whereas the composite panel to be formed was raised to a certain preheating temperature. The preconsolidated GF/PP panel, heated by contact heating in an external heater above the melting temperature of PP matrix, was then formed in the cold metal mold. Typical cycle times (including preheating and stamping) were in the range of 3–4 min. Secondly, a novel rod-bed mold was designed to manufacture three-dimensional parts using the same forming technique. Both halves of the mold were made of several tiny round metal rods in a metal frame. This rod-bed mold allowed to duplicate any solid contour by pushing it slightly on to the spring loaded rods. The final position of these rods could be fixed by forcing the side plates of the metal frame together. As an example, a saddle shaped, three-dimensional contour could be fairly well reproduced by stamp forming GF/PP composites with this rod-bed mold. The latter can have enormous potential in the manufacturing of medical devices such as adjustable prostheses or splints where only a limited number of parts with complex geometry have to be formed.
Mehdi Nikforooz - One of the best experts on this subject based on the ideXlab platform.
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Assessment of failure toughening mechanisms in Continuous Glass Fiber thermoplastic laminates subjected to cyclic loading
Composites Part B: Engineering, 2019Co-Authors: Mehdi Nikforooz, Mahmood M. ShokriehAbstract:Abstract Tensile fatigue behaviour of Glass Fiber/polyamide composites, including unidirectional ([0]8, [90]8) and cross-ply ([02/902]s, [04/904]s and [904/04]s) laminates, was studied and compared to that of similar Glass Fiber/epoxy composites. The fatigue resistance of cross-ply Glass/polyamide was greater than that of Glass/epoxy while also exhibiting lower stiffness reduction. To explain this key observation, residual stiffness and residual strength fatigue tests were performed on cross-ply laminates, while optical microscopy was used to measure ply crack density during the different stages of cycling. Testing of the cross-ply laminates at lower peak stresses of 50% of the ultimate tensile strength (i.e., high cycle fatigue regime) revealed partial cracks that did not propagate completely through the width and thickness of plies due to high matrix toughness and other observed toughening mechanisms such as matrix bridging. A micromechanical finite element model with explicit ply cracks was also used to predict laminate stiffness degradation corresponding to observed ply crack densities, revealing that stiffness degradation was overpredicted when cracks were assumed to span the entire specimen width. Additional finite element simulations with partial cracks showed notably less stiffness reduction. These observations suggest Glass/polyamide is inherently more damage tolerant than Glass/epoxy and may be a suitable replacement for fatigue critical structures.
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processability and tensile performance of Continuous Glass Fiber polyamide laminates for structural load bearing applications
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:Abstract The performance of Continuous E-Glass/polyamide 6 laminates processed using distinct hot press moulding cycles was assessed and compared with similar E-Glass/epoxy and E-Glass/polypropylene laminates. The effects of peak processing temperature, preheating time, and temperature dwell time on laminate consolidation and quality were observed using optical and scanning electron microscopy. Corresponding quasi-static tensile tests were performed on [0] 8 , [90] 8 , [0 2 /90 2 ] s , [0 4 /90 4 ] s and [±45] 2s laminates. Compared to E-Glass/epoxy composites, the [0] 8 specimens presented a similar strength, while the [90] 8 specimens exhibited a much lower strength due to weaker Fiber/matrix adhesion. Conversely, the E-Glass/polyamide cross-ply laminates had a markedly higher strength while exhibiting the same modulus. This is because of higher toughness; the polyamide matrix provides as was proved by higher transverse matrix cracking strain of E-Glass/polyamide. These findings support the feasibility of producing cost-effective and high-quality E-Glass/polyamide laminates for use in high-performance applications, which is an attractive alternative to more conventional Glass/epoxy laminates.
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Processability and tensile performance of Continuous Glass Fiber/polyamide laminates for structural load-bearing applications
Composites Part A: Applied Science and Manufacturing, 2018Co-Authors: Mehdi Nikforooz, Mohammad Golzar, Mahmood M. Shokrieh, John MontesanoAbstract:Abstract The performance of Continuous E-Glass/polyamide 6 laminates processed using distinct hot press moulding cycles was assessed and compared with similar E-Glass/epoxy and E-Glass/polypropylene laminates. The effects of peak processing temperature, preheating time, and temperature dwell time on laminate consolidation and quality were observed using optical and scanning electron microscopy. Corresponding quasi-static tensile tests were performed on [0] 8 , [90] 8 , [0 2 /90 2 ] s , [0 4 /90 4 ] s and [±45] 2s laminates. Compared to E-Glass/epoxy composites, the [0] 8 specimens presented a similar strength, while the [90] 8 specimens exhibited a much lower strength due to weaker Fiber/matrix adhesion. Conversely, the E-Glass/polyamide cross-ply laminates had a markedly higher strength while exhibiting the same modulus. This is because of higher toughness; the polyamide matrix provides as was proved by higher transverse matrix cracking strain of E-Glass/polyamide. These findings support the feasibility of producing cost-effective and high-quality E-Glass/polyamide laminates for use in high-performance applications, which is an attractive alternative to more conventional Glass/epoxy laminates.
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Assessment of the thermomechanical performance of Continuous Glass Fiber-reinforced thermoplastic laminates
Polymer Testing, 2018Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:Abstract The effects of temperature on the static tensile behavior of Continuous E-Glass/polyamide laminates were studied in order to assess the feasibility of using the material system for structural applications. Uniaxial tensile tests were conducted on [0]8, [90]8, [02/902]s and [04/904]s laminates at multiple temperatures above and below the Glass transition temperature, which was measured using different methods. Optical and scanning electron microscopy were performed on the tested samples, and the effects of temperature on failure modes were investigated. The [0]8 and [90]8 laminates displayed three reduction stages in modulus versus temperature, where the largest reduction was in the Glass transition region as a result of notable softening of the polyamide matrix, as confirmed by fractographic analysis. However, the [02/902]s and [04/904]s laminates displayed the largest modulus reduction prior to the Glass transition temperature with little reduction beyond, which was attributed to matrix softening coupled with in situ ply constraining effects.
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Thermomechanical Behavior of Continuous Glass Fiber-reinforced Polyamide Composite Laminates
American Society for Composites 2017, 2017Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:E-Glass/polyamide laminates were fabricated using a hot press and the effects of temperature on static tensile behavior was studied both below and above the Glass transition temperature of the material. The Glass transition temperature was determined using DMA. Uniaxial tensile tests were conducted on [0]8, [90]8, [02/902]s and [04,904]s laminates at room temperature, as well as at multiple temperatures above and below the Glass transition temperature. Finally, the Young’s modulus and strength of the specimens were evaluated versus temperature, fractography was performed on the fractured [0]8 samples and the effect of temperature on failure modes was investigated. [0]8 and [90]8 laminates displayed three reduction stages in modulus and strength versus temperature where the largest reduction was in Glass transition region. However, [02/902]s and [04/904]s laminates displayed the largest reduction before the Glass transition temperature. These experimental findings were compared with the rule of mixtures and classical lamination theory.
Mahmood M. Shokrieh - One of the best experts on this subject based on the ideXlab platform.
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Assessment of failure toughening mechanisms in Continuous Glass Fiber thermoplastic laminates subjected to cyclic loading
Composites Part B: Engineering, 2019Co-Authors: Mehdi Nikforooz, Mahmood M. ShokriehAbstract:Abstract Tensile fatigue behaviour of Glass Fiber/polyamide composites, including unidirectional ([0]8, [90]8) and cross-ply ([02/902]s, [04/904]s and [904/04]s) laminates, was studied and compared to that of similar Glass Fiber/epoxy composites. The fatigue resistance of cross-ply Glass/polyamide was greater than that of Glass/epoxy while also exhibiting lower stiffness reduction. To explain this key observation, residual stiffness and residual strength fatigue tests were performed on cross-ply laminates, while optical microscopy was used to measure ply crack density during the different stages of cycling. Testing of the cross-ply laminates at lower peak stresses of 50% of the ultimate tensile strength (i.e., high cycle fatigue regime) revealed partial cracks that did not propagate completely through the width and thickness of plies due to high matrix toughness and other observed toughening mechanisms such as matrix bridging. A micromechanical finite element model with explicit ply cracks was also used to predict laminate stiffness degradation corresponding to observed ply crack densities, revealing that stiffness degradation was overpredicted when cracks were assumed to span the entire specimen width. Additional finite element simulations with partial cracks showed notably less stiffness reduction. These observations suggest Glass/polyamide is inherently more damage tolerant than Glass/epoxy and may be a suitable replacement for fatigue critical structures.
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processability and tensile performance of Continuous Glass Fiber polyamide laminates for structural load bearing applications
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:Abstract The performance of Continuous E-Glass/polyamide 6 laminates processed using distinct hot press moulding cycles was assessed and compared with similar E-Glass/epoxy and E-Glass/polypropylene laminates. The effects of peak processing temperature, preheating time, and temperature dwell time on laminate consolidation and quality were observed using optical and scanning electron microscopy. Corresponding quasi-static tensile tests were performed on [0] 8 , [90] 8 , [0 2 /90 2 ] s , [0 4 /90 4 ] s and [±45] 2s laminates. Compared to E-Glass/epoxy composites, the [0] 8 specimens presented a similar strength, while the [90] 8 specimens exhibited a much lower strength due to weaker Fiber/matrix adhesion. Conversely, the E-Glass/polyamide cross-ply laminates had a markedly higher strength while exhibiting the same modulus. This is because of higher toughness; the polyamide matrix provides as was proved by higher transverse matrix cracking strain of E-Glass/polyamide. These findings support the feasibility of producing cost-effective and high-quality E-Glass/polyamide laminates for use in high-performance applications, which is an attractive alternative to more conventional Glass/epoxy laminates.
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Processability and tensile performance of Continuous Glass Fiber/polyamide laminates for structural load-bearing applications
Composites Part A: Applied Science and Manufacturing, 2018Co-Authors: Mehdi Nikforooz, Mohammad Golzar, Mahmood M. Shokrieh, John MontesanoAbstract:Abstract The performance of Continuous E-Glass/polyamide 6 laminates processed using distinct hot press moulding cycles was assessed and compared with similar E-Glass/epoxy and E-Glass/polypropylene laminates. The effects of peak processing temperature, preheating time, and temperature dwell time on laminate consolidation and quality were observed using optical and scanning electron microscopy. Corresponding quasi-static tensile tests were performed on [0] 8 , [90] 8 , [0 2 /90 2 ] s , [0 4 /90 4 ] s and [±45] 2s laminates. Compared to E-Glass/epoxy composites, the [0] 8 specimens presented a similar strength, while the [90] 8 specimens exhibited a much lower strength due to weaker Fiber/matrix adhesion. Conversely, the E-Glass/polyamide cross-ply laminates had a markedly higher strength while exhibiting the same modulus. This is because of higher toughness; the polyamide matrix provides as was proved by higher transverse matrix cracking strain of E-Glass/polyamide. These findings support the feasibility of producing cost-effective and high-quality E-Glass/polyamide laminates for use in high-performance applications, which is an attractive alternative to more conventional Glass/epoxy laminates.
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Assessment of the thermomechanical performance of Continuous Glass Fiber-reinforced thermoplastic laminates
Polymer Testing, 2018Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:Abstract The effects of temperature on the static tensile behavior of Continuous E-Glass/polyamide laminates were studied in order to assess the feasibility of using the material system for structural applications. Uniaxial tensile tests were conducted on [0]8, [90]8, [02/902]s and [04/904]s laminates at multiple temperatures above and below the Glass transition temperature, which was measured using different methods. Optical and scanning electron microscopy were performed on the tested samples, and the effects of temperature on failure modes were investigated. The [0]8 and [90]8 laminates displayed three reduction stages in modulus versus temperature, where the largest reduction was in the Glass transition region as a result of notable softening of the polyamide matrix, as confirmed by fractographic analysis. However, the [02/902]s and [04/904]s laminates displayed the largest modulus reduction prior to the Glass transition temperature with little reduction beyond, which was attributed to matrix softening coupled with in situ ply constraining effects.
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Thermomechanical Behavior of Continuous Glass Fiber-reinforced Polyamide Composite Laminates
American Society for Composites 2017, 2017Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:E-Glass/polyamide laminates were fabricated using a hot press and the effects of temperature on static tensile behavior was studied both below and above the Glass transition temperature of the material. The Glass transition temperature was determined using DMA. Uniaxial tensile tests were conducted on [0]8, [90]8, [02/902]s and [04,904]s laminates at room temperature, as well as at multiple temperatures above and below the Glass transition temperature. Finally, the Young’s modulus and strength of the specimens were evaluated versus temperature, fractography was performed on the fractured [0]8 samples and the effect of temperature on failure modes was investigated. [0]8 and [90]8 laminates displayed three reduction stages in modulus and strength versus temperature where the largest reduction was in Glass transition region. However, [02/902]s and [04/904]s laminates displayed the largest reduction before the Glass transition temperature. These experimental findings were compared with the rule of mixtures and classical lamination theory.
John Montesano - One of the best experts on this subject based on the ideXlab platform.
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processability and tensile performance of Continuous Glass Fiber polyamide laminates for structural load bearing applications
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:Abstract The performance of Continuous E-Glass/polyamide 6 laminates processed using distinct hot press moulding cycles was assessed and compared with similar E-Glass/epoxy and E-Glass/polypropylene laminates. The effects of peak processing temperature, preheating time, and temperature dwell time on laminate consolidation and quality were observed using optical and scanning electron microscopy. Corresponding quasi-static tensile tests were performed on [0] 8 , [90] 8 , [0 2 /90 2 ] s , [0 4 /90 4 ] s and [±45] 2s laminates. Compared to E-Glass/epoxy composites, the [0] 8 specimens presented a similar strength, while the [90] 8 specimens exhibited a much lower strength due to weaker Fiber/matrix adhesion. Conversely, the E-Glass/polyamide cross-ply laminates had a markedly higher strength while exhibiting the same modulus. This is because of higher toughness; the polyamide matrix provides as was proved by higher transverse matrix cracking strain of E-Glass/polyamide. These findings support the feasibility of producing cost-effective and high-quality E-Glass/polyamide laminates for use in high-performance applications, which is an attractive alternative to more conventional Glass/epoxy laminates.
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Processability and tensile performance of Continuous Glass Fiber/polyamide laminates for structural load-bearing applications
Composites Part A: Applied Science and Manufacturing, 2018Co-Authors: Mehdi Nikforooz, Mohammad Golzar, Mahmood M. Shokrieh, John MontesanoAbstract:Abstract The performance of Continuous E-Glass/polyamide 6 laminates processed using distinct hot press moulding cycles was assessed and compared with similar E-Glass/epoxy and E-Glass/polypropylene laminates. The effects of peak processing temperature, preheating time, and temperature dwell time on laminate consolidation and quality were observed using optical and scanning electron microscopy. Corresponding quasi-static tensile tests were performed on [0] 8 , [90] 8 , [0 2 /90 2 ] s , [0 4 /90 4 ] s and [±45] 2s laminates. Compared to E-Glass/epoxy composites, the [0] 8 specimens presented a similar strength, while the [90] 8 specimens exhibited a much lower strength due to weaker Fiber/matrix adhesion. Conversely, the E-Glass/polyamide cross-ply laminates had a markedly higher strength while exhibiting the same modulus. This is because of higher toughness; the polyamide matrix provides as was proved by higher transverse matrix cracking strain of E-Glass/polyamide. These findings support the feasibility of producing cost-effective and high-quality E-Glass/polyamide laminates for use in high-performance applications, which is an attractive alternative to more conventional Glass/epoxy laminates.
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Assessment of the thermomechanical performance of Continuous Glass Fiber-reinforced thermoplastic laminates
Polymer Testing, 2018Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:Abstract The effects of temperature on the static tensile behavior of Continuous E-Glass/polyamide laminates were studied in order to assess the feasibility of using the material system for structural applications. Uniaxial tensile tests were conducted on [0]8, [90]8, [02/902]s and [04/904]s laminates at multiple temperatures above and below the Glass transition temperature, which was measured using different methods. Optical and scanning electron microscopy were performed on the tested samples, and the effects of temperature on failure modes were investigated. The [0]8 and [90]8 laminates displayed three reduction stages in modulus versus temperature, where the largest reduction was in the Glass transition region as a result of notable softening of the polyamide matrix, as confirmed by fractographic analysis. However, the [02/902]s and [04/904]s laminates displayed the largest modulus reduction prior to the Glass transition temperature with little reduction beyond, which was attributed to matrix softening coupled with in situ ply constraining effects.
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Thermomechanical Behavior of Continuous Glass Fiber-reinforced Polyamide Composite Laminates
American Society for Composites 2017, 2017Co-Authors: Mehdi Nikforooz, John Montesano, Mohammad Golzar, Mahmood M. ShokriehAbstract:E-Glass/polyamide laminates were fabricated using a hot press and the effects of temperature on static tensile behavior was studied both below and above the Glass transition temperature of the material. The Glass transition temperature was determined using DMA. Uniaxial tensile tests were conducted on [0]8, [90]8, [02/902]s and [04,904]s laminates at room temperature, as well as at multiple temperatures above and below the Glass transition temperature. Finally, the Young’s modulus and strength of the specimens were evaluated versus temperature, fractography was performed on the fractured [0]8 samples and the effect of temperature on failure modes was investigated. [0]8 and [90]8 laminates displayed three reduction stages in modulus and strength versus temperature where the largest reduction was in Glass transition region. However, [02/902]s and [04/904]s laminates displayed the largest reduction before the Glass transition temperature. These experimental findings were compared with the rule of mixtures and classical lamination theory.
J Denault - One of the best experts on this subject based on the ideXlab platform.
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fatigue resistance of Continuous Glass Fiber polypropylene composites consolidation dependence
Composites Science and Technology, 2004Co-Authors: M N Bureau, J DenaultAbstract:Abstract The effect of consolidation on the fatigue resistance of Continuous Glass Fiber/polypropylene (CGF/PP) composites was studied. Five sets of conditions, chosen to approach plant-like processing conditions, were used to obtain samples with varying consolidation quality. These conditions resulted in different void content, degree of crystallinity, size of crystalline entities (spherulites) and level of Fiber dispersion. Although they led to different short-term (flexural, tensile or short-beam shear) mechanical results, a single linear correlation could be established between the interlaminar shear strength (ISS) and the void content for all consolidation conditions except one. The fatigue resistance of the CGF/PP composites showed that these consolidation conditions also resulted in different fatigue damage evolution and fatigue resistance curves (or S–N curves). From the S–N curves, two useful correlations could be established: the first is a linear correlation between the Basquin's fatigue strength and the short-term flexural strength; the second is a linear correlation between the Basquin's fatigue sensitivity and ISS. The results emphasize the predominance of the Fiber–matrix interface in determining the general mechanical properties of Continuous Fiber composites and suggest that short-term flexural and short-beam shear tests can be useful empirical indicators of the long-term performance of CGF/PP composites.
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thermoforming stamping of Continuous Glass Fiber polypropylene composites interlaminar and tool laminate shear properties
Journal of Thermoplastic Composite Materials, 2004Co-Authors: Gilbert Lebrun, M N Bureau, J DenaultAbstract: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...
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Fatigue resistance of Continuous Glass Fiber/polypropylene composites: consolidation dependence
Composites Science and Technology, 2004Co-Authors: M N Bureau, J DenaultAbstract:Abstract The effect of consolidation on the fatigue resistance of Continuous Glass Fiber/polypropylene (CGF/PP) composites was studied. Five sets of conditions, chosen to approach plant-like processing conditions, were used to obtain samples with varying consolidation quality. These conditions resulted in different void content, degree of crystallinity, size of crystalline entities (spherulites) and level of Fiber dispersion. Although they led to different short-term (flexural, tensile or short-beam shear) mechanical results, a single linear correlation could be established between the interlaminar shear strength (ISS) and the void content for all consolidation conditions except one. The fatigue resistance of the CGF/PP composites showed that these consolidation conditions also resulted in different fatigue damage evolution and fatigue resistance curves (or S–N curves). From the S–N curves, two useful correlations could be established: the first is a linear correlation between the Basquin's fatigue strength and the short-term flexural strength; the second is a linear correlation between the Basquin's fatigue sensitivity and ISS. The results emphasize the predominance of the Fiber–matrix interface in determining the general mechanical properties of Continuous Fiber composites and suggest that short-term flexural and short-beam shear tests can be useful empirical indicators of the long-term performance of CGF/PP composites.
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Fatigue resistance of Continuous Glass Fiber/polypropylene composites: Temperature dependence
Polymer Composites, 2004Co-Authors: M N Bureau, J DenaultAbstract:The effect of testing temperature on the fatigue resistance of Continuous Glass Fiber/polypropylene (CGF/PP) composites was studied. Fatigue resistance curves (or S-N curves) were obtained at −40°C, 23°C and 50°C. Both on an absolute stress basis and on a normalized stress basis (with respect to the yield stress at the temperature considered), the S-N curves showed that CGF/PP composites had excellent fatigue performance at 23°C and that their performance was actually improved at −40°C (below Tg of the PP matrix). The S-N curves at 50°C showed that, although the composite flexural strength was reduced because of PP matrix softening, their fatigue performance remained relatively high, as it is controlled by the CGF reinforcement. Comparison with a CGF/thermoset isophthalic polyester composite of identical Fiber architecture and similar flexural strength at 23°C indicated that the properties of the thermoplastic PP matrix provided improved fatigue resistance, both on an absolute and a normalized basis, especially below the Glass transition temperature. It was concluded that the fact that the fatigue performance of the CGF/polyester composite is only weakly temperature-dependent, while that of the CGF/PP composite is strongly temperature-dependent, does not necessarily mean that it shows superior performance. Polym. Compos. 25:622–629, 2004. © 2004 Society of Plastics Engineers.
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Thermoforming-Stamping of Continuous Glass Fiber/Polypropylene Composites: Interlaminar and Tool–Laminate Shear Properties
Journal of Thermoplastic Composite Materials, 2004Co-Authors: Gilbert Lebrun, M N Bureau, J DenaultAbstract: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...