The aim of this study is to develop an appropriate modeling methodology for the simulation of intralaminar damage in laminated composites under complex loadings. The intralaminar damages are modeled by stiffness reduction controlled by thermodynamic forces as defined in continuum damage mechanics model proposed by Ladeveze. The original method neglected transverse stress in elementary plies during the tensile tests of [45/?45]mS laminates, resulting in variations of the identified damage parameters of Ladeveze model. This study compared the identified damage parameters considering transverse stress effects with those based on the original method. The effect of transverse stress in the identification process on the damage modeling is discussed, and it is found that one of damage coupling parameters and the damage master curves significantly depend on consideration of transverse stress effects. Finally, it is demonstrated that experimental stiffness degradation is well simulated by the prediction using the identified parameters considering transverse stress effects.
{"title":"Identification of Damage Parameters for Intralaminar Damage Modeling in Laminated Composites Considering Transverse Stress Effects","authors":"Rehs T. Gerrit, S. Kokubo, T. Yokozeki","doi":"10.4236/OJCM.2017.74012","DOIUrl":"https://doi.org/10.4236/OJCM.2017.74012","url":null,"abstract":"The aim of this study is to develop an appropriate modeling methodology for the simulation of intralaminar damage in laminated composites under complex loadings. The intralaminar damages are modeled by stiffness reduction controlled by thermodynamic forces as defined in continuum damage mechanics model proposed by Ladeveze. The original method neglected transverse stress in elementary plies during the tensile tests of [45/?45]mS laminates, resulting in variations of the identified damage parameters of Ladeveze model. This study compared the identified damage parameters considering transverse stress effects with those based on the original method. The effect of transverse stress in the identification process on the damage modeling is discussed, and it is found that one of damage coupling parameters and the damage master curves significantly depend on consideration of transverse stress effects. Finally, it is demonstrated that experimental stiffness degradation is well simulated by the prediction using the identified parameters considering transverse stress effects.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"185-196"},"PeriodicalIF":0.0,"publicationDate":"2017-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46847935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wiranphat Thodsaratpreeyakul, P. Uawongsuwan, A. Kataoka, Takanori Negoro, H. Hamada
The interfacial shear strength value measuring by the modified Kelly-Tyson equation method was studied the measurement accuracy. The measuring accuracy by using the modified Kelly-Tyson equation method is compared to the nano-indentation testing method. The results and an influential factor are described. An error in the modified Kelly-Tyson equation is verified to avoid the incorrect measurement when the interfacial shear strength was measured by the modified Kelly-Tyson equation. To study the different interfacial shear strength behavior, short fiber reinforced PET composites were fabricated. In this study, an advance fabricating technique for short fiber reinforced composite as direct fiber feeding process is conducted to fabricate GF/recycled PET for studying the interfacial shear strength. The result indicates that the modified Kelly-Tyson equation method accurately provides the accurate interfacial shear strength value, if it is conducted with the sample without a horizontally aligned fiber. So the high fiber loading content sample should be avoided to get the more accuracy result. The large horizontally aligned fiber area into specimens extremely resulted in the incorrect measurement of the interfacial shear strength value by the modified Kelly-Tyson equation method. The fiber agglomeration factor and the sensitively horizontally aligned fiber area must be considered its influence on the measuring for improving the equation effectiveness.
{"title":"The Determination of Interfacial Shear Strength in Short Fiber Reinforced Poly Ethylene Terephthalate by Kelly-Tyson Theory","authors":"Wiranphat Thodsaratpreeyakul, P. Uawongsuwan, A. Kataoka, Takanori Negoro, H. Hamada","doi":"10.4236/OJCM.2017.74015","DOIUrl":"https://doi.org/10.4236/OJCM.2017.74015","url":null,"abstract":"The interfacial shear strength value measuring by the modified Kelly-Tyson equation method was studied the measurement accuracy. The measuring accuracy by using the modified Kelly-Tyson equation method is compared to the nano-indentation testing method. The results and an influential factor are described. An error in the modified Kelly-Tyson equation is verified to avoid the incorrect measurement when the interfacial shear strength was measured by the modified Kelly-Tyson equation. To study the different interfacial shear strength behavior, short fiber reinforced PET composites were fabricated. In this study, an advance fabricating technique for short fiber reinforced composite as direct fiber feeding process is conducted to fabricate GF/recycled PET for studying the interfacial shear strength. The result indicates that the modified Kelly-Tyson equation method accurately provides the accurate interfacial shear strength value, if it is conducted with the sample without a horizontally aligned fiber. So the high fiber loading content sample should be avoided to get the more accuracy result. The large horizontally aligned fiber area into specimens extremely resulted in the incorrect measurement of the interfacial shear strength value by the modified Kelly-Tyson equation method. The fiber agglomeration factor and the sensitively horizontally aligned fiber area must be considered its influence on the measuring for improving the equation effectiveness.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"218-226"},"PeriodicalIF":0.0,"publicationDate":"2017-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47202837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The bending strength of carbon fiber/thermoplastic epoxy composites (CF/TP-EP Compo.) had bi-linear increasewith increase of weight-average molecular weight (Mw) of matrix. The transition in the bending strength appeared at around 55k of Mw (“k” means 103). SEM observation of fractured surface of CF/TP-EP Compo. showed that the fracture mode changed from interfacial failure to fiber breakage dominated failure. The smooth surface of carbon fibers appeared at lower Mw than 55k while some resin remained on the fibers indicating good adhesion between carbon fiber and matrix at higher Mw than 55k. The interfacial shear strength between carbon fiber and matrix bi-linearly increased with an increase of Mw similarly to the bending strength of the composite, measured by the micro droplet test. The dynamic loss tanδ of the matrix measured at 2 Hz also showed a bi-linear relationship with respect to Mw having a knee point at Mw = 55k. The connection probability of two cracks introduced on each side of specimens also confirmed that the interfacial strength between carbon fiber and matrix is the key for the mechanical performance of CF/TP-EP Compo. in bending.
{"title":"Improvement of Bending Strength of Carbon Fiber/Thermoplastic Epoxy Composites —Effects of Molecular Weight of Epoxy on Carbon Fiber/Matrix Interfacial Strength and Connection of Cracks in Matrix","authors":"H. Nishida, K. Okubo, T. Fujii, V. Carvelli","doi":"10.4236/OJCM.2017.74014","DOIUrl":"https://doi.org/10.4236/OJCM.2017.74014","url":null,"abstract":"The bending strength of carbon fiber/thermoplastic epoxy composites (CF/TP-EP Compo.) had bi-linear increasewith increase of weight-average molecular weight (Mw) of matrix. The transition in the bending strength appeared at around 55k of Mw (“k” means 103). SEM observation of fractured surface of CF/TP-EP Compo. showed that the fracture mode changed from interfacial failure to fiber breakage dominated failure. The smooth surface of carbon fibers appeared at lower Mw than 55k while some resin remained on the fibers indicating good adhesion between carbon fiber and matrix at higher Mw than 55k. The interfacial shear strength between carbon fiber and matrix bi-linearly increased with an increase of Mw similarly to the bending strength of the composite, measured by the micro droplet test. The dynamic loss tanδ of the matrix measured at 2 Hz also showed a bi-linear relationship with respect to Mw having a knee point at Mw = 55k. The connection probability of two cracks introduced on each side of specimens also confirmed that the interfacial strength between carbon fiber and matrix is the key for the mechanical performance of CF/TP-EP Compo. in bending.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"207-217"},"PeriodicalIF":0.0,"publicationDate":"2017-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42685384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. García-Pérez, C. Menchaca-Campos, M. A. García-Sánchez, Elsa Pereyra-Laguna, Ociel Rodríguez-Pérez, J. Uruchurtu-Chavarín
This research was based on the manufacture of new composite materials that offer technological possibilities in the development of new devices with greater efficiency. Electrospinning was used to form nylon 66/-tetra-(para-aminophenyl) porphyrin (H2T(p-NH2)PP)/graphene oxide (GO) composite film. Graphene oxide coatings were obtained from graphite, through mechanical exfoliation followed by calcination and ultrasonic agitation in an oxidant solution. These samples were characterized under SEM, FTIR, Raman spectroscopy, UV-vis and R-X techniques. On the other hand, H2T(p-NH2)PP was synthesized in two steps process by the Rothemun reaction and the Adler Method and it was integrated within nylon polyamide fibers by direct addition of a hexamethylenediamine/adipoyl chloride reactant mixture. The polymerization of the nylon/H2T(p-NH2)PP species occurs in such a way that it starts or ends on the four peripherals-NH2 groups, connected and located in the same molecular plane of H2T(p-NH2)PP, forming nylon chains at the periphery of the macrocycle. The association of GO with nylon/H2T(p-NH2)PP fibers is performed by dipole-dipole interaction and hydrogen bonding. To take advantage of the properties of these materials, they were combined as a ternary composite.
{"title":"Nylon/Porphyrin/Graphene Oxide Fiber Ternary Composite, Synthesis and Characterization","authors":"C. García-Pérez, C. Menchaca-Campos, M. A. García-Sánchez, Elsa Pereyra-Laguna, Ociel Rodríguez-Pérez, J. Uruchurtu-Chavarín","doi":"10.4236/OJCM.2017.73009","DOIUrl":"https://doi.org/10.4236/OJCM.2017.73009","url":null,"abstract":"This research was based on the manufacture of new composite \u0000materials that offer technological possibilities in the development of new \u0000devices with greater efficiency. Electrospinning was used to form nylon \u000066/-tetra-(para-aminophenyl) porphyrin (H2T(p-NH2)PP)/graphene oxide \u0000(GO) composite film. Graphene oxide coatings were obtained from graphite, \u0000through mechanical exfoliation followed by calcination and ultrasonic agitation \u0000in an oxidant solution. These samples were characterized under SEM, FTIR, Raman \u0000spectroscopy, UV-vis and R-X techniques. On the other hand, H2T(p-NH2)PP \u0000was synthesized in two steps process by the Rothemun reaction and the Adler Method and it was \u0000integrated within nylon polyamide fibers by direct addition of a \u0000hexamethylenediamine/adipoyl chloride reactant mixture. The polymerization of \u0000the nylon/H2T(p-NH2)PP species occurs in such a way that \u0000it starts or ends on the four peripherals-NH2 groups, connected \u0000and located in the same molecular plane of H2T(p-NH2)PP, \u0000forming nylon chains at the periphery of the macrocycle. The association of GO \u0000with nylon/H2T(p-NH2)PP fibers is performed by \u0000dipole-dipole interaction and hydrogen bonding. To take advantage of the \u0000properties of these materials, they were combined as a ternary composite.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"146-165"},"PeriodicalIF":0.0,"publicationDate":"2017-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45692247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guided by the belief that Fermi energy EF (equivalently, chemical potential μ) plays a pivotal role in determining the properties of superconductors (SCs), we have recently derived μ-incorporated Generalized-Bardeen-Cooper-Schrieffer equations (GBCSEs) for the gaps (Δs) and critical temperatures (Tcs) of both elemental and composite SCs. The μ-dependent interaction parameters consistent with the values of Δs and Tcs of any of these SCs were shown to lead to expressions for the effective mass of electrons (m*) and their number density (ns), critical velocity (v0), and the critical current density j0 at T = 0 in terms of the following five parameters: Debye temperature, EF, a dimensionless construct y, the specific heat constant, and the gram-atomic volume. We could then fix the value of μ in any SC by appealing to the experimental value of its j0 and calculate the other parameters. This approach was followed for a variety of SCs—elemental, MgB2 and cuprates and, with a more accurate equation to determine y, for Nitrogen Nitride (NbN). Employing the framework given for NbN, we present here a detailed study of Ba0.6K0.4Fe2As2 (BaAs). Some of the main attributes of this SC are: it is characterized by -wave superconductivity and multiple gaps between 0 - 12 meV; its Tc ~ 37 K, but the maximum Tc of SCs in its class can exceed 50 K; EF/kTc = 4.4 (k = Boltzmann constant), and its Tc plotted against a tuning variable has a dome-like structure. After drawing attention to the fact that the -wave is an inbuilt feature of GBCSEs, we give a quantitative account of its several other features, which include the values of m*, ns, vo, and coherence length. Finally, we also deal with the issue of the stage BaAs occupies in the BCS-Bose-Einstein Condensation crossover.
{"title":"On the s±-Wave Superconductivity in the Iron-Based Superconductors: A Perspective Based on a Detailed Study of Ba0.6K0.4Fe2As2 via the Generalized-Bardeen-Cooper-Schrieffer Equations Incorporating Fermi Energy","authors":"G. P. Malik","doi":"10.4236/OJCM.2017.73008","DOIUrl":"https://doi.org/10.4236/OJCM.2017.73008","url":null,"abstract":"Guided by the belief that Fermi energy EF (equivalently, \u0000chemical potential μ) plays a pivotal role in determining the \u0000properties of superconductors (SCs), we have recently derived μ-incorporated \u0000Generalized-Bardeen-Cooper-Schrieffer equations (GBCSEs) for the gaps (Δs) \u0000and critical temperatures (Tcs) of both elemental and \u0000composite SCs. The μ-dependent interaction parameters consistent \u0000with the values of Δs and Tcs of any of these SCs were \u0000shown to lead to expressions for the effective mass of electrons (m*) \u0000and their number density (ns), critical velocity (v0), \u0000and the critical current density j0 at T = 0 in \u0000terms of the following five parameters: Debye temperature, EF, \u0000a dimensionless construct y, the specific heat constant, and the gram-atomic \u0000volume. We could then fix the value of μ in any SC by \u0000appealing to the experimental value of its j0 and \u0000calculate the other parameters. This approach was followed for a variety of SCs—elemental, MgB2 and cuprates and, with a more accurate equation to determine y, for \u0000Nitrogen Nitride (NbN). Employing the framework given for NbN, we present here \u0000a detailed study of Ba0.6K0.4Fe2As2 (BaAs). \u0000Some of the main attributes of this SC are: it is characterized by -wave superconductivity and \u0000multiple gaps between 0 - 12 meV; its Tc ~ 37 K, but the maximum Tc of SCs in its class \u0000can exceed 50 K; EF/kTc = 4.4 (k = \u0000Boltzmann constant), and its Tc plotted against a \u0000tuning variable has a dome-like structure. After drawing attention to the fact \u0000that the -wave is an inbuilt feature of GBCSEs, we give a quantitative account of \u0000its several other features, which include the values of m*, ns, vo, \u0000and coherence length. Finally, we also deal with the issue of the stage BaAs \u0000occupies in the BCS-Bose-Einstein Condensation crossover.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"130-145"},"PeriodicalIF":0.0,"publicationDate":"2017-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48372527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Acoustic Emission Testing (AT) is one of the major non-destructive testing methods used for severity evaluation of structures. Amplitude distributions of AE signals are characterized by b-value and the value is mainly used for the severity evaluation of concrete structures until now. The value is assumed to be independent with propagation distance between acoustic emission sources to AE sensors. We evaluate the influence of the wide frequency band encountered in the fracture behavior of glass fiber reinforced plastic (GFRP) on the b-value analysis. In tensile tests, the b-value was determined from an acoustic emission (AE) source generated near a centered hole in a specimen of GFRP. At 15 mm from the hole, the b-value analysis indicated a decreasing trend with increasing tensile stress. At a propagation length of 45 mm, farthest from the hole, a small number of AE signals were received. The attenuation is more rapid for high-frequency AE signals. Thus, the amplitude distribution bandwidth is wide and the b-value changes. This change in b-value for GFRPs is investigated by analyzing the spectral components of the AE signals. For a single-frequency AE source, the b-value is unchanged with propagation length. In contrast, multiple-frequency AE sources produce changes in b-value proportional to the fraction of each spectral component in the received signal. This is due to the frequency dependence of the attenuation with propagation length. From these results, the b-value analysis cannot be applied to considering frequency dependence of AE attenuation.
{"title":"Frequency Dependence of the b-Value Used for Acoustic Emission Analysis of Glass Fiber Reinforced Plastics","authors":"D. Jung, Y. Mizutani, A. Todoroki, Yoshiro Suzuki","doi":"10.4236/OJCM.2017.73007","DOIUrl":"https://doi.org/10.4236/OJCM.2017.73007","url":null,"abstract":"Acoustic Emission Testing (AT) \u0000is one of the major non-destructive testing methods used for severity \u0000evaluation of structures. Amplitude distributions of AE signals are \u0000characterized by b-value and the value is mainly used for the \u0000severity evaluation of concrete structures until now. The value is assumed to \u0000be independent with propagation distance between acoustic emission sources to \u0000AE sensors. We evaluate the influence of the wide frequency band encountered in \u0000the fracture behavior of glass fiber reinforced plastic (GFRP) on the b-value \u0000analysis. In tensile tests, the b-value was determined from an \u0000acoustic emission (AE) source generated near a centered hole in a specimen of \u0000GFRP. At 15 mm from the hole, the b-value analysis indicated a \u0000decreasing trend with increasing tensile stress. At a propagation length of 45 \u0000mm, farthest from the hole, a small number of AE signals were received. The attenuation is more rapid \u0000for high-frequency AE signals. Thus, the amplitude distribution bandwidth is \u0000wide and the b-value changes. This change in b-value \u0000for GFRPs is investigated by analyzing the spectral components of the AE \u0000signals. For a single-frequency AE source, the b-value is unchanged \u0000with propagation length. In contrast, multiple-frequency AE sources produce changes in b-value \u0000proportional to the fraction of each spectral component in the received signal. \u0000This is due to the frequency dependence of the attenuation with propagation \u0000length. From these results, the b-value analysis cannot be applied to \u0000considering frequency dependence of AE attenuation.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"117-129"},"PeriodicalIF":0.0,"publicationDate":"2017-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42155072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Holger Seidlitz, S. Fritzsche, M. Ambrosio, Alexander Kloshek
Organic sheets made out of fiber-reinforced thermoplastics are able to make a crucial contribution to increase the lightweight potential of a design. They show high specific strength- and stiffness properties, good damping characteristics and recycling capabilities, while being able to show a higher energy absorption capacity than comparable metal constructions. Nowadays, multi-material designs are an established way in the automotive industry to combine the benefits of metal and fiber-reinforced plastics. Currently used technologies for the joining of organic sheets and metals in large-scale production are mechanical joining technologies and adhesive technologies. Both techniques require large overlapping areas that are not required in the design of the part. Additionally, mechanical joining is usually combined with “fiber-destroying” pre-drilling and punching processes. This will disturb the force flux at the joining location by causing unwanted fiber- and inter-fiber failure and inducing critical notch stresses. Therefore, the multi-material design with fiber-reinforced thermoplastics and metals needs optimized joining techniques that don’t interrupt the force flux, so that higher loads can be induced and the full benefit of the FRP material can be used. This article focuses on the characterization of a new joining technology, based on the Cold Metal Transfer (CMT) welding process that allows joining of organic sheets and metals in a load path optimized way, with short cycle times. This is achieved by redirecting the fibers around the joining area by the insertion of a thin metal pin. The path of the fibers will be similar to paths of fibers inside structures found in nature, e.g. a knothole inside of a tree. As a result of the bionic fiber design of the joint, high joining strengths can be achieved. The increase of the joint strength compared to blind riveting was performed and proven with stainless steel and orthotropic reinforced composites in shear-tests based on the DIN EN ISO 14273. Every specimen joined with the new CMT Pin joining technology showed a higher strength than specimens joined with one blind rivet. Specimens joined with two or three pin rows show a higher strength than specimens joined with two blind rivets.
由纤维增强热塑性塑料制成的有机板材能够为增加设计的轻量化潜力做出重要贡献。它们表现出高比强度和刚度性能，良好的阻尼特性和回收能力，同时能够表现出比同类金属结构更高的能量吸收能力。如今，多材料设计是汽车行业结合金属和纤维增强塑料优点的一种既定方式。目前大规模生产中使用的有机板材与金属的连接技术有机械连接技术和粘合技术。这两种技术都需要在零件设计中不需要的大重叠区域。此外，机械连接通常与“破坏纤维”的预钻和冲孔工艺相结合。这将通过引起不必要的纤维和纤维间破坏和诱导临界缺口应力来干扰连接位置的力通量。因此，纤维增强热塑性塑料与金属的复合材料设计需要优化连接技术，使其不中断力通量，从而诱导更高的载荷，充分发挥FRP材料的优势。本文重点介绍了一种基于冷金属转移(CMT)焊接工艺的新连接技术的特性，该技术允许以负载路径优化的方式与短周期时间连接有机板材和金属。这是通过在连接区域周围插入薄金属引脚来重新定向纤维来实现的。纤维的路径将类似于在自然界中发现的结构内部的纤维路径，例如树内部的节孔。由于关节采用仿生纤维设计，可以获得较高的连接强度。在基于DIN EN ISO 14273的剪切试验中，用不锈钢和正交异性增强复合材料进行了与盲铆接相比接缝强度的增加。采用新型CMT销连接技术连接的试件强度均高于采用盲钉连接的试件。用两排或三排销钉连接的试件比用两排盲钉连接的试件具有更高的强度。
{"title":"Advanced Welding Technology for Highly Stressable Multi-Material Designs with Fiber-Reinforced Plastics and Metals","authors":"Holger Seidlitz, S. Fritzsche, M. Ambrosio, Alexander Kloshek","doi":"10.4236/OJCM.2017.73010","DOIUrl":"https://doi.org/10.4236/OJCM.2017.73010","url":null,"abstract":"Organic sheets made out of fiber-reinforced thermoplastics are able to make a crucial contribution to increase the lightweight potential of a design. They show high specific strength- and stiffness properties, good damping characteristics and recycling capabilities, while being able to show a higher energy absorption capacity than comparable metal constructions. Nowadays, multi-material designs are an established way in the automotive industry to combine the benefits of metal and fiber-reinforced plastics. Currently used technologies for the joining of organic sheets and metals in large-scale production are mechanical joining technologies and adhesive technologies. Both techniques require large overlapping areas that are not required in the design of the part. Additionally, mechanical joining is usually combined with “fiber-destroying” pre-drilling and punching processes. This will disturb the force flux at the joining location by causing unwanted fiber- and inter-fiber failure and inducing critical notch stresses. Therefore, the multi-material design with fiber-reinforced thermoplastics and metals needs optimized joining techniques that don’t interrupt the force flux, so that higher loads can be induced and the full benefit of the FRP material can be used. This article focuses on the characterization of a new joining technology, based on the Cold Metal Transfer (CMT) welding process that allows joining of organic sheets and metals in a load path optimized way, with short cycle times. This is achieved by redirecting the fibers around the joining area by the insertion of a thin metal pin. The path of the fibers will be similar to paths of fibers inside structures found in nature, e.g. a knothole inside of a tree. As a result of the bionic fiber design of the joint, high joining strengths can be achieved. The increase of the joint strength compared to blind riveting was performed and proven with stainless steel and orthotropic reinforced composites in shear-tests based on the DIN EN ISO 14273. Every specimen joined with the new CMT Pin joining technology showed a higher strength than specimens joined with one blind rivet. Specimens joined with two or three pin rows show a higher strength than specimens joined with two blind rivets.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"166-177"},"PeriodicalIF":0.0,"publicationDate":"2017-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46220340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, using calcium chloride and sodium molybdate as raw material, polyethylene glycol (PEG2000) as surfactant, the nanocomposites of CaMoO4: Eu3+ were prepared by a direct feeding microwave synthesis method. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM) and photoluminescence spectrum (PL). The XRD Pattern showed that the samples are scheelite structure of CaMoO4. The SEM image showed that the majority of as-prepared sample is a relatively flake structure, and some fine particles attached to it. PL spectra showed that as-prepared samples have strong luminescence properties; it had purity red emission at 615 nm. The effects of different Eu3+ ions doping amount and surface active agent on the photoluminescence properties were studied. The results showed that when the molar ratio of Eu3+ was 0.10, PEG2000 as surfactant, the luminescence intensity of as-prepared sample was maximum.
{"title":"Microwave Synthesis and Photoluminescence Properties of CaMoO4:Eu0.13+ Nanocomposites","authors":"Qiuci Li, Xiaomei Zeng, Shuibin Yang, Xuehong Liao","doi":"10.4236/OJCM.2017.72006","DOIUrl":"https://doi.org/10.4236/OJCM.2017.72006","url":null,"abstract":"In this paper, using calcium chloride and sodium molybdate as raw material, polyethylene glycol (PEG2000) as surfactant, the nanocomposites of CaMoO4: Eu3+ were prepared by a direct feeding microwave synthesis method. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM) and photoluminescence spectrum (PL). The XRD Pattern showed that the samples are scheelite structure of CaMoO4. The SEM image showed that the majority of as-prepared sample is a relatively flake structure, and some fine particles attached to it. PL spectra showed that as-prepared samples have strong luminescence properties; it had purity red emission at 615 nm. The effects of different Eu3+ ions doping amount and surface active agent on the photoluminescence properties were studied. The results showed that when the molar ratio of Eu3+ was 0.10, PEG2000 as surfactant, the luminescence intensity of as-prepared sample was maximum.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"99-104"},"PeriodicalIF":0.0,"publicationDate":"2017-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48849756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present work, inverse thermal analysis of heat conduction is carried out to estimate the in-plane thermal conductivity of composites. Numerical simulations were performed to determine the optimal configuration of the heating system to ensure a unidirectional heat transfer in the composite sample. Composite plates made of unsaturated polyester resin and unidirectional glass fibers were fabricated by injection to validate the methodology. A heating and cooling cycle is applied at the bottom and top surfaces of the sample. The thermal conductivity can be deduced from transient temperature measurements given by thermocouples positioned at three chosen locations along the fibers direction. The inverse analysis algorithm is initiated by solving the direct problem defined by the one-dimensional transient heat conduction equation using a first estimate of thermal conductivity. The integral in time of the square distance between the measured and predicted values is the criterion minimized in the inverse analysis algorithm. Finally, the evolution of the in-plane composite thermal conductivity can be deduced from the experimental results by the rule of mixture.
{"title":"Measurement of the In-Plane Thermal Conductivity of Long Fiber Composites by Inverse Analysis","authors":"B. Assaf, V. Sobotka, F. Trochu","doi":"10.4236/OJCM.2017.72005","DOIUrl":"https://doi.org/10.4236/OJCM.2017.72005","url":null,"abstract":"In the present work, inverse thermal analysis of heat conduction is carried out to estimate the in-plane thermal conductivity of composites. Numerical simulations were performed to determine the optimal configuration of the heating system to ensure a unidirectional heat transfer in the composite sample. Composite plates made of unsaturated polyester resin and unidirectional glass fibers were fabricated by injection to validate the methodology. A heating and cooling cycle is applied at the bottom and top surfaces of the sample. The thermal conductivity can be deduced from transient temperature measurements given by thermocouples positioned at three chosen locations along the fibers direction. The inverse analysis algorithm is initiated by solving the direct problem defined by the one-dimensional transient heat conduction equation using a first estimate of thermal conductivity. The integral in time of the square distance between the measured and predicted values is the criterion minimized in the inverse analysis algorithm. Finally, the evolution of the in-plane composite thermal conductivity can be deduced from the experimental results by the rule of mixture.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"85-98"},"PeriodicalIF":0.0,"publicationDate":"2017-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44465098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present research, commercially pure Ti (grade-2) has been diffusion bonded with Ti and Cu plate under static force without any interlayers. The diffusion bonded samples were tested for micro hardness and micro structural analysis through optical microscopy and SEM. It is found from the present investigation that the bonded zone is affected by the processing variables such as bonding time (1 - 2 h), bonding force (250 N), bonding temperature (973 - 1073 K) and surface roughness. Results of the investigation revealed that temperature range of ?973 - 1073 K along with time duration of 1 - 2 hours in vacuum has resulted in a joint having high hardness with minimum pores. Hardness of the bond depends on the grain boundary diffusion at the interface and maximum hardness was achieved in the case of Ti-Cu joints. When Ti-Cu plates were used for bonding at 973 K for 2 hours, Cu-Ti solid solution along with a zone of different intermetallics was formed in the bonded zone. However, at higher temperatures, no continuous zone of intermetallics was found in the bonded region but instead Ti-Cu solid solution appeared.
{"title":"Scanning Electron Microscopy (SEM) Analysis and Hardness of Diffusion Bonded Titanium-Titanium and Titanium-Copper Plates with Static Force and without Interlayers","authors":"J. Hemanth","doi":"10.4236/OJCM.2017.72007","DOIUrl":"https://doi.org/10.4236/OJCM.2017.72007","url":null,"abstract":"In the present research, commercially pure Ti (grade-2) has been diffusion bonded with Ti and Cu plate under static force without any interlayers. The diffusion bonded samples were tested for micro hardness and micro structural analysis through optical microscopy and SEM. It is found from the present investigation that the bonded zone is affected by the processing variables such as bonding time (1 - 2 h), bonding force (250 N), bonding temperature (973 - 1073 K) and surface roughness. Results of the investigation revealed that temperature range of ?973 - 1073 K along with time duration of 1 - 2 hours in vacuum has resulted in a joint having high hardness with minimum pores. Hardness of the bond depends on the grain boundary diffusion at the interface and maximum hardness was achieved in the case of Ti-Cu joints. When Ti-Cu plates were used for bonding at 973 K for 2 hours, Cu-Ti solid solution along with a zone of different intermetallics was formed in the bonded zone. However, at higher temperatures, no continuous zone of intermetallics was found in the bonded region but instead Ti-Cu solid solution appeared.","PeriodicalId":57868,"journal":{"name":"复合材料期刊(英文)","volume":"07 1","pages":"105-116"},"PeriodicalIF":0.0,"publicationDate":"2017-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48739304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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