To enhance the mechanical properties of the adhesive layer in joints, a thin–structural open–cell porous Ni–foam was embedded into the adhesive interface through ultrasonics (US) assisted. The porous metal foam is effective in interlocking itself with adhesive. After the ultrasonic vibration was applied for 0.17 s, the adhesive penetrated Ni–foam, generating enough residue. This technique effectively improves the energy absorption and shear strength of the CFRP/Al single lap joint by more than 250.33% and 118.4% with a 0.5 mm thick Ni–foam insert, respectively. The fatigue resistance increased by 154% with a 0.3 mm thick Ni–foam insert based on the fatigue testing results and the Weibull distribution method. The S–N curves were established at different reliabilities for engineering applications. With the Ni–Foam insert, the failure modes were changed through crack deflexion, Ni–Foam degumming, and crack blocking.HighlightsUltrasonic vibration assisting Ni‐foam inserts CFRP/Al adhesive joints.The shear strength of joints with Ni‐foam was maximally increased by 118.4%.The fracture forms of joints with Ni‐foam were changed.The fatigue life of the joints with Ni‐foam was maximally increased by 154%.S–N curve of joint with Ni–foam of different reliability levels was got.
{"title":"Thin porous Ni‐foam enhanced CFRP/Al adhesive joint inserted by ultrasonic vibration","authors":"Zhengwu Zhou, Yongfei Wang, Chao Chen","doi":"10.1002/pc.29040","DOIUrl":"https://doi.org/10.1002/pc.29040","url":null,"abstract":"<jats:label/>To enhance the mechanical properties of the adhesive layer in joints, a thin–structural open–cell porous Ni–foam was embedded into the adhesive interface through ultrasonics (US) assisted. The porous metal foam is effective in interlocking itself with adhesive. After the ultrasonic vibration was applied for 0.17 s, the adhesive penetrated Ni–foam, generating enough residue. This technique effectively improves the energy absorption and shear strength of the CFRP/Al single lap joint by more than 250.33% and 118.4% with a 0.5 mm thick Ni–foam insert, respectively. The fatigue resistance increased by 154% with a 0.3 mm thick Ni–foam insert based on the fatigue testing results and the Weibull distribution method. The S–N curves were established at different reliabilities for engineering applications. With the Ni–Foam insert, the failure modes were changed through crack deflexion, Ni–Foam degumming, and crack blocking.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>Ultrasonic vibration assisting Ni‐foam inserts CFRP/Al adhesive joints.</jats:list-item> <jats:list-item>The shear strength of joints with Ni‐foam was maximally increased by 118.4%.</jats:list-item> <jats:list-item>The fracture forms of joints with Ni‐foam were changed.</jats:list-item> <jats:list-item>The fatigue life of the joints with Ni‐foam was maximally increased by 154%.</jats:list-item> <jats:list-item>S–N curve of joint with Ni–foam of different reliability levels was got.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"7 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thulasidhas Dhilipkumar, Raja Venkatesan, Vinayak S. Hiremath, S. Kesavan, Karuppusamy P, Karthik V. Shankar, Osamah Alduhaish
Adhesively bonded joints play a vital role in improving the structural performance of 3D‐printed components. This research aims to examine the effect of graphene inclusion on the failure load and vibrational behavior of polylactic acid flat‐joggle‐flat (FJF) joints prepared using fused deposition modeling. The present research focused on the effect of print directions (0°, 45°, 90°) and the inclusion of graphene nanofiller (0.25, 0.50, 0.75, and 1.00 wt%) on the performance of FJF joints. The effect of raster direction on mechanical properties was examined by tensile testing of dog‐bone samples. Results showed that 0° print orientation had higher tensile strength compared to other printing directions. Shear testing of FJF joints indicated that the inclusion of graphene has enhanced the strength of 3D‐printed FJF joints by 61.18%. Fractography results showed that the formation of the shear band with the inclusion of 0.50 wt% graphene helps to distribute the stress more evenly and prevent catastrophic failure of the FJF joint. The free vibrational test revealed that the inclusion of 0.50 wt% graphene had improved the natural frequencies, as the presence of graphene‐enhanced the interfacial bonding between FJF adherend and adhesive.Highlights0° print orientation had higher tensile strength than other printing directions.Inclusion of graphene‐enhanced the shear strength of flat‐joggle‐flat (FJF) joints by 61.18%.Shear band formation delayed the failure of graphene‐reinforced FJF joints.FJF reinforced with 0.50 wt% graphene had adherend failure.FJF joint added with 1.0 wt% graphene had lower natural frequencies.
{"title":"Enhancing structural performance of 3D‐printed adhesively bonded flat‐joggle‐flat polymer joints with graphene‐reinforced adhesive","authors":"Thulasidhas Dhilipkumar, Raja Venkatesan, Vinayak S. Hiremath, S. Kesavan, Karuppusamy P, Karthik V. Shankar, Osamah Alduhaish","doi":"10.1002/pc.29037","DOIUrl":"https://doi.org/10.1002/pc.29037","url":null,"abstract":"<jats:label/>Adhesively bonded joints play a vital role in improving the structural performance of 3D‐printed components. This research aims to examine the effect of graphene inclusion on the failure load and vibrational behavior of polylactic acid flat‐joggle‐flat (FJF) joints prepared using fused deposition modeling. The present research focused on the effect of print directions (0°, 45°, 90°) and the inclusion of graphene nanofiller (0.25, 0.50, 0.75, and 1.00 wt%) on the performance of FJF joints. The effect of raster direction on mechanical properties was examined by tensile testing of dog‐bone samples. Results showed that 0° print orientation had higher tensile strength compared to other printing directions. Shear testing of FJF joints indicated that the inclusion of graphene has enhanced the strength of 3D‐printed FJF joints by 61.18%. Fractography results showed that the formation of the shear band with the inclusion of 0.50 wt% graphene helps to distribute the stress more evenly and prevent catastrophic failure of the FJF joint. The free vibrational test revealed that the inclusion of 0.50 wt% graphene had improved the natural frequencies, as the presence of graphene‐enhanced the interfacial bonding between FJF adherend and adhesive.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>0° print orientation had higher tensile strength than other printing directions.</jats:list-item> <jats:list-item>Inclusion of graphene‐enhanced the shear strength of flat‐joggle‐flat (FJF) joints by 61.18%.</jats:list-item> <jats:list-item>Shear band formation delayed the failure of graphene‐reinforced FJF joints.</jats:list-item> <jats:list-item>FJF reinforced with 0.50 wt% graphene had adherend failure.</jats:list-item> <jats:list-item>FJF joint added with 1.0 wt% graphene had lower natural frequencies.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"10 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the gradual acceleration of development in the modern electronics, there is a higher demand for insulating polymer composites with high thermal conductivity. Herein, the functionalized fillers were fabricated through first deposition of polydopamine (PDA) on boron nitride (BN) plates and then covalent modification of BN‐PDA and aluminum oxide (Al2O3) by γ‐aminopropyltriethoxysilane (APTES), respectively. Hybridized filler‐filled polycarbonate (PC) composites were prepared by partially substituting Al2O3 for BN plates with constant filler content. The PC composite filled with 9 wt% Al2O3 and 21 wt% BN (PCA3B7) achieved a thermal conductivity of 0.734 W mk−1, which is 217% and 21% higher than that of pure PC (0.231 W mk−1) and PCB (0.605 W mk−1), respectively. Besides, the PC composites exhibit excellent electrical insulation properties (1013 Ω cm), relatively good mechanical properties, and enhanced thermal stability. This PC composite, characterized by its superior comprehensive performance, holds significant promise as a thermal management material in electrical and electronic device applications.HighlightsFunctionalized fillers were fabricated via covalent and non‐covalent methods.The appropriate proportion of hybridized fillers showed synergistic effects.The composite's thermal conductivity was 217% higher than pure PC.The composite exhibited desirable electrical insulating characteristics and thermal stability.The composite could act as a thermal management material.
随着现代电子技术的发展，人们对具有高导热性的绝缘聚合物复合材料提出了更高的要求。本文首先在氮化硼（BN）板上沉积聚多巴胺（PDA），然后用γ-氨基丙基三乙氧基硅烷（APTES）分别对 BN-PDA 和氧化铝（Al2O3）进行共价改性，从而制备出功能化填料。在填充物含量不变的情况下，用 Al2O3 部分替代 BN 板，制备了杂化填充聚碳酸酯（PC）复合材料。填充了 9 wt% Al2O3 和 21 wt% BN 的 PC 复合材料（PCA3B7）的导热系数达到 0.734 W mk-1，分别比纯 PC（0.231 W mk-1）和 PCB（0.605 W mk-1）高出 217% 和 21%。此外，PC 复合材料还具有优异的电绝缘性能（1013 Ω cm）、相对较好的机械性能和更强的热稳定性。这种 PC 复合材料具有优异的综合性能，有望成为电气和电子设备应用中的热管理材料。通过共价和非共价方法制备了功能化填料，适当比例的杂化填料显示出协同效应。复合材料的热导率比纯 PC 高 217%。该复合材料具有理想的电绝缘特性和热稳定性。该复合材料可用作热管理材料。
{"title":"Construction of denser networks via functionalized aluminum oxide‐boron nitride hybrid fillers: Towards improved thermal conductivity of polycarbonate composites","authors":"Fang Feng, Yongbiao Luo, Ruyi Yang, Zhiheng Zhao","doi":"10.1002/pc.29009","DOIUrl":"https://doi.org/10.1002/pc.29009","url":null,"abstract":"<jats:label/>With the gradual acceleration of development in the modern electronics, there is a higher demand for insulating polymer composites with high thermal conductivity. Herein, the functionalized fillers were fabricated through first deposition of polydopamine (PDA) on boron nitride (BN) plates and then covalent modification of BN‐PDA and aluminum oxide (Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) by γ‐aminopropyltriethoxysilane (APTES), respectively. Hybridized filler‐filled polycarbonate (PC) composites were prepared by partially substituting Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> for BN plates with constant filler content. The PC composite filled with 9 wt% Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> and 21 wt% BN (PCA<jats:sub>3</jats:sub>B<jats:sub>7</jats:sub>) achieved a thermal conductivity of 0.734 W mk<jats:sup>−1</jats:sup>, which is 217% and 21% higher than that of pure PC (0.231 W mk<jats:sup>−1</jats:sup>) and PCB (0.605 W mk<jats:sup>−1</jats:sup>), respectively. Besides, the PC composites exhibit excellent electrical insulation properties (10<jats:sup>13</jats:sup> Ω cm), relatively good mechanical properties, and enhanced thermal stability. This PC composite, characterized by its superior comprehensive performance, holds significant promise as a thermal management material in electrical and electronic device applications.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>Functionalized fillers were fabricated via covalent and non‐covalent methods.</jats:list-item> <jats:list-item>The appropriate proportion of hybridized fillers showed synergistic effects.</jats:list-item> <jats:list-item>The composite's thermal conductivity was 217% higher than pure PC.</jats:list-item> <jats:list-item>The composite exhibited desirable electrical insulating characteristics and thermal stability.</jats:list-item> <jats:list-item>The composite could act as a thermal management material.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"42 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mariam Keskes, Melinda Desse, Christian Carrot, Mohamed Jaziri
Poly(butylene adipate‐co‐terephthalate) with or without thermoplastic starch is often used as a biodegradable matrix in composites reinforced with 5 and 10 wt% of either microfibrillated cellulose or cellulose nanocrystals. If dispersion of the fillers is well studied, their orientation in melt blended composites requires further understanding. In this study, the effect of a controlled shear rate on the orientation of the filler was investigated to understand how shear rate affects orientation and how orientation affects mechanical properties of the composites. To this end, composites prepared by melt mixing and then compressed were taken as a reference state of low orientation. On the contrary, to orient the fillers, extrusion through a slit die with a determined shear rate was carried out. Results of tensile tests, microscopic observations, atomic force microscopy and dynamic mechanical analysis in the melt showed that orientation of fillers in the flow axis was possible for shear rates higher than 13 s−1. The orientated samples presented enhanced mechanical properties in the elastic domain as opposed to unoriented samples. In general, orientation of fillers leads to uniaxial stiffness at lower filler content with much better ductility. However, this was observed only on samples for which the percolation of the filler was not obtained in the unoriented state, otherwise, orientation proved to be detrimental to the elastic mechanical properties because of the rupture in the formed network.HighlightsOrientation can be controlled during processing.Sufficient shear rate is required.Orientation improves mechanical properties.Orientation might have a negative effect on rigidity in case of existing network.
{"title":"Effect of shear rate on orientation of cellulosic nanofibers and nanocrystals in poly(butylene adipate‐co‐terephthalate) based composites","authors":"Mariam Keskes, Melinda Desse, Christian Carrot, Mohamed Jaziri","doi":"10.1002/pc.29023","DOIUrl":"https://doi.org/10.1002/pc.29023","url":null,"abstract":"<jats:label/>Poly(butylene adipate‐<jats:italic>co</jats:italic>‐terephthalate) with or without thermoplastic starch is often used as a biodegradable matrix in composites reinforced with 5 and 10 wt% of either microfibrillated cellulose or cellulose nanocrystals. If dispersion of the fillers is well studied, their orientation in melt blended composites requires further understanding. In this study, the effect of a controlled shear rate on the orientation of the filler was investigated to understand how shear rate affects orientation and how orientation affects mechanical properties of the composites. To this end, composites prepared by melt mixing and then compressed were taken as a reference state of low orientation. On the contrary, to orient the fillers, extrusion through a slit die with a determined shear rate was carried out. Results of tensile tests, microscopic observations, atomic force microscopy and dynamic mechanical analysis in the melt showed that orientation of fillers in the flow axis was possible for shear rates higher than 13 s<jats:sup>−1</jats:sup>. The orientated samples presented enhanced mechanical properties in the elastic domain as opposed to unoriented samples. In general, orientation of fillers leads to uniaxial stiffness at lower filler content with much better ductility. However, this was observed only on samples for which the percolation of the filler was not obtained in the unoriented state, otherwise, orientation proved to be detrimental to the elastic mechanical properties because of the rupture in the formed network.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>Orientation can be controlled during processing.</jats:list-item> <jats:list-item>Sufficient shear rate is required.</jats:list-item> <jats:list-item>Orientation improves mechanical properties.</jats:list-item> <jats:list-item>Orientation might have a negative effect on rigidity in case of existing network.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"96 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanical properties of short carbon fiber‐reinforced nylon 6 (CF‐PA6) components formed by fused filament fabrication (FFF) are significantly affected by the process parameters of additive manufacturing and heat treatment. In this study, the effects of printing speed, carbon fiber aspect ratio, and annealing temperature on fiber orientation were investigated by observation of single‐layer‐single‐fiber samples. Furthermore, a two‐stage annealing process was proposed to increase the tensile modulus of CF‐PA6 based on the correlation analysis results between the degree of fiber alignment and the variation of tensile modulus. According to the calculation of the Pearson correlation coefficient, the tensile modulus was highly correlated with the degree of fiber alignment under different printing speeds and fiber aspect ratios. The variation in tensile modulus and fiber orientation was also consistent when the annealing temperature was lower than the crystallization temperature. Conversely, the variation of tensile modulus and fiber orientation were opposite, as the annealing temperature was higher than the crystallization temperature because of the influence of crystallinity. Through increasing the degree of fiber alignment and crystallinity of the parts, the proposed two‐stage annealing method could increase the tensile modulus of the parts to 9.0 GPa, which was 16.81% higher than that of single‐temperature annealing.HighlightsThe effects of annealing temperature, carbon fiber aspect ratio and printing speed on fiber orientation were illustrated.The relationship between the degree of fiber alignment and the variation of tensile modulus was established.The proposed two‐stage annealing method, considering fiber orientation and crystallinity, significantly increased the tensile modulus of CF270‐PA6 parts from 7.7 to 9.0 GPa.The quantitative analysis of the fiber orientation is realized by the statistical analysis of the plane fiber orientation angle of the single‐layer‐single‐fiber sample.
{"title":"Two‐stage annealing method for short carbon fiber‐reinforced nylon 6 in fused filament fabrication","authors":"Bin Liu, Bo Xin, Wenfu Zhu, Bo Zhang, Yijian Pang","doi":"10.1002/pc.29012","DOIUrl":"https://doi.org/10.1002/pc.29012","url":null,"abstract":"<jats:label/>The mechanical properties of short carbon fiber‐reinforced nylon 6 (CF‐PA6) components formed by fused filament fabrication (FFF) are significantly affected by the process parameters of additive manufacturing and heat treatment. In this study, the effects of printing speed, carbon fiber aspect ratio, and annealing temperature on fiber orientation were investigated by observation of single‐layer‐single‐fiber samples. Furthermore, a two‐stage annealing process was proposed to increase the tensile modulus of CF‐PA6 based on the correlation analysis results between the degree of fiber alignment and the variation of tensile modulus. According to the calculation of the Pearson correlation coefficient, the tensile modulus was highly correlated with the degree of fiber alignment under different printing speeds and fiber aspect ratios. The variation in tensile modulus and fiber orientation was also consistent when the annealing temperature was lower than the crystallization temperature. Conversely, the variation of tensile modulus and fiber orientation were opposite, as the annealing temperature was higher than the crystallization temperature because of the influence of crystallinity. Through increasing the degree of fiber alignment and crystallinity of the parts, the proposed two‐stage annealing method could increase the tensile modulus of the parts to 9.0 GPa, which was 16.81% higher than that of single‐temperature annealing.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>The effects of annealing temperature, carbon fiber aspect ratio and printing speed on fiber orientation were illustrated.</jats:list-item> <jats:list-item>The relationship between the degree of fiber alignment and the variation of tensile modulus was established.</jats:list-item> <jats:list-item>The proposed two‐stage annealing method, considering fiber orientation and crystallinity, significantly increased the tensile modulus of CF270‐PA6 parts from 7.7 to 9.0 GPa.</jats:list-item> <jats:list-item>The quantitative analysis of the fiber orientation is realized by the statistical analysis of the plane fiber orientation angle of the single‐layer‐single‐fiber sample.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"59 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is more and more difficult to identify defects in carbon fiber composite materials due to the difficulty in making defect samples and the single signal analysis method. In order to better solve the problem of defect identification in carbon fiber composite materials, this study uses ultrasonic phased array equipment to quantitatively locate and detect carbon fiber composite laminates with embedded delamination defects, so as to more intuitively and effectively display the appearance of different delamination defects. The time domain analysis of the collected ultrasonic original signal and the time‐frequency domain analysis using wavelet packet are carried out. A total of 6 eigenvalues were extracted to reflect the ultrasonic signals of different delamination defects. By using genetic algorithm to optimize BP neural network, the recognition accuracy of delamination defects of different sizes is more than 95%, and the recognition accuracy of delamination defects of different depths is 100%, so as to realize the effective intelligent recognition of delamination defects of different sizes and depths of carbon fiber composites. This study is of great significance to improve the accuracy and reliability of defect identification of carbon fiber composite materials.HighlightsThe ultrasonic phased array equipment is used to quantitatively locate the carbon fiber composite laminates with embedded delamination defects, so that the appearance of different defects can be displayed more intuitively and effectively.Using time domain analysis and time‐frequency domain analysis based on wavelet packet, the combination of the two can more comprehensively extract the effective features of the defect signal.The BP neural network is optimized by genetic algorithm, and the results can effectively and automatically identify different layered defects, which lays a good foundation for the rapid and accurate identification of more defects in the future.
由于碳纤维复合材料缺陷取样困难、信号分析方法单一等原因，碳纤维复合材料的缺陷识别越来越困难。为了更好地解决碳纤维复合材料的缺陷识别问题，本研究利用超声相控阵设备对嵌入分层缺陷的碳纤维复合材料层压板进行定量定位和检测，从而更直观有效地显示不同分层缺陷的外观。对采集到的超声波原始信号进行时域分析，并利用小波包进行时频域分析。共提取了 6 个特征值来反映不同分层缺陷的超声波信号。通过遗传算法优化 BP 神经网络，不同尺寸分层缺陷的识别准确率达到 95% 以上，不同深度分层缺陷的识别准确率达到 100%，从而实现了对碳纤维复合材料不同尺寸和深度分层缺陷的有效智能识别。该研究对提高碳纤维复合材料缺陷识别的准确性和可靠性具有重要意义。 亮点 利用超声相控阵设备对嵌入分层缺陷的碳纤维复合材料层压板进行定量定位，从而更直观有效地显示不同缺陷的外观。利用时域分析和基于小波包的时频域分析，二者结合能更全面地提取缺陷信号的有效特征。通过遗传算法对 BP 神经网络进行优化，结果可以有效自动识别不同层次的缺陷，为今后快速准确地识别更多缺陷奠定了良好的基础。
{"title":"Research on defect identification of carbon fiber composite materials based on ultrasonic phased array","authors":"Ziang Jing, Gaoshen Cai, Xiang Yu, Bingxu Wang","doi":"10.1002/pc.29033","DOIUrl":"https://doi.org/10.1002/pc.29033","url":null,"abstract":"<jats:label/>It is more and more difficult to identify defects in carbon fiber composite materials due to the difficulty in making defect samples and the single signal analysis method. In order to better solve the problem of defect identification in carbon fiber composite materials, this study uses ultrasonic phased array equipment to quantitatively locate and detect carbon fiber composite laminates with embedded delamination defects, so as to more intuitively and effectively display the appearance of different delamination defects. The time domain analysis of the collected ultrasonic original signal and the time‐frequency domain analysis using wavelet packet are carried out. A total of 6 eigenvalues were extracted to reflect the ultrasonic signals of different delamination defects. By using genetic algorithm to optimize BP neural network, the recognition accuracy of delamination defects of different sizes is more than 95%, and the recognition accuracy of delamination defects of different depths is 100%, so as to realize the effective intelligent recognition of delamination defects of different sizes and depths of carbon fiber composites. This study is of great significance to improve the accuracy and reliability of defect identification of carbon fiber composite materials.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>The ultrasonic phased array equipment is used to quantitatively locate the carbon fiber composite laminates with embedded delamination defects, so that the appearance of different defects can be displayed more intuitively and effectively.</jats:list-item> <jats:list-item>Using time domain analysis and time‐frequency domain analysis based on wavelet packet, the combination of the two can more comprehensively extract the effective features of the defect signal.</jats:list-item> <jats:list-item>The BP neural network is optimized by genetic algorithm, and the results can effectively and automatically identify different layered defects, which lays a good foundation for the rapid and accurate identification of more defects in the future.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"5 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoxiao Ji, Jinhui Wang, Zhiming Wang, Bowei Mao, Yizhong Cao, Yanjun Xie, Yutao Yan
Bamboo‐based composite, being an eco‐friendly green material, has garnered widespread utilization across diverse sectors including construction and domestic appliances owing to its impressive strength, innate aesthetic appeal, and wear resistance. However, it tends to crack at bonding interface between bamboo and the brittle resin adhesive due to stress concentration, reducing its mechanical properties and lifespan. To address this issue, the epoxy‐based polyhedral oligomeric silsesquioxane (POSS) was incorporated to modify the phenol‐formaldehyde (PF) resin and improve the interfacial bonding strength. And the results showed that the incorporation of 5% epoxy‐POSS could markedly increase the impact and flexural strength of the modified PF resin by 75.7% and 27.6%, respectively, in contrast to the original PF resin. Moreover, the dry and wet shear strength of bamboo‐PF composites bonded by the POSS modified PF resin adhesive was also apparently improved by 17.03% and 28.55%, respectively. The increased toughness and bonding strength were mainly attributed to the nano‐effect of POSS and good compatibility and cross‐linking reaction with the PF resin, which helped dissipate energy and avoid stress concentration within the PF resin and at the bonding interface. This study aims to address the cracking problem of bamboo‐based composites and extend their longevity in architectural and domestic applications.HighlightsEpoxy‐POSS disperse well in PF resin due to its unique multi‐epoxy structure.Epoxy‐POSS can react with PF resin and effectively improve its toughness.Nano‐effect and cross‐linking effect enable dissipate energy and disperses stress.Modification increased bonding strength and decreased interfacial cracking.
{"title":"Epoxy‐POSS toughened phenol‐formaldehyde resin adhesive and its enhancement on the interfacial bonding strength of bamboo based composite","authors":"Xiaoxiao Ji, Jinhui Wang, Zhiming Wang, Bowei Mao, Yizhong Cao, Yanjun Xie, Yutao Yan","doi":"10.1002/pc.29031","DOIUrl":"https://doi.org/10.1002/pc.29031","url":null,"abstract":"<jats:label/>Bamboo‐based composite, being an eco‐friendly green material, has garnered widespread utilization across diverse sectors including construction and domestic appliances owing to its impressive strength, innate aesthetic appeal, and wear resistance. However, it tends to crack at bonding interface between bamboo and the brittle resin adhesive due to stress concentration, reducing its mechanical properties and lifespan. To address this issue, the epoxy‐based polyhedral oligomeric silsesquioxane (POSS) was incorporated to modify the phenol‐formaldehyde (PF) resin and improve the interfacial bonding strength. And the results showed that the incorporation of 5% epoxy‐POSS could markedly increase the impact and flexural strength of the modified PF resin by 75.7% and 27.6%, respectively, in contrast to the original PF resin. Moreover, the dry and wet shear strength of bamboo‐PF composites bonded by the POSS modified PF resin adhesive was also apparently improved by 17.03% and 28.55%, respectively. The increased toughness and bonding strength were mainly attributed to the nano‐effect of POSS and good compatibility and cross‐linking reaction with the PF resin, which helped dissipate energy and avoid stress concentration within the PF resin and at the bonding interface. This study aims to address the cracking problem of bamboo‐based composites and extend their longevity in architectural and domestic applications.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>Epoxy‐POSS disperse well in PF resin due to its unique multi‐epoxy structure.</jats:list-item> <jats:list-item>Epoxy‐POSS can react with PF resin and effectively improve its toughness.</jats:list-item> <jats:list-item>Nano‐effect and cross‐linking effect enable dissipate energy and disperses stress.</jats:list-item> <jats:list-item>Modification increased bonding strength and decreased interfacial cracking.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"118 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, carbon fiber (CF) filled polyphenylene sulfide (PPS) composites are lubricated with perfluoropolymer (PFP) fiber by melt‐blending. The effect of double fibers (CF‐PFP fibers) on the tribological properties of PPS composites has been carefully investigated and correlated under various sliding conditions. The results indicated that the tribological performance of PPS composites with double fibers is better than that of the composites with a single fiber, especially under severe conditions. Mechanism exploration suggests that a double‐fiber hybrid structure between a hard CF and a soft PFP fiber could tightly entrap the CF by fibril entanglement, thus preventing the CF from being stripped out of the matrix under the steel ring shearing force. Under optimized conditions, the average friction coefficient of composites with PFP fiber is only about 0.1 at 300 N load under 200 rpm, even lower than half of the average friction coefficient of the composites with PTFE powder under the same condition. Notably, compared to commercial split PFP fibers, the in‐situ formed PFP fibers with more uniform distribution significantly improve the tribological properties. This work open up a novel perspective for improving the tribological performance of composites by systematically regulating the microstructure of self‐lubricating fibrous additives.HighlightsPFA is subject to in‐situ fibrillation during melt blending.Fibrous PFP effectively improves the tribological properties of PPS/CF composites.The in‐situ formed PFP fiber contributes to better tribological properties.The double‐fiber hybrid structure prevents the CF from being sheared out.The number of processing cycles affects the tribological properties.
{"title":"Tribological properties of perfluoropolymer fiber filled carbon fiber/polyphenylene sulfide composites: Effect of in‐situ fibrillated fiber or split fiber","authors":"Xiaotao Qiu, Bin Luo, Aiqun Gu, Wenjian Tang, Meiju Xie, Siqi Tang, Zili Yu","doi":"10.1002/pc.29016","DOIUrl":"https://doi.org/10.1002/pc.29016","url":null,"abstract":"<jats:label/>In this study, carbon fiber (CF) filled polyphenylene sulfide (PPS) composites are lubricated with perfluoropolymer (PFP) fiber by melt‐blending. The effect of double fibers (CF‐PFP fibers) on the tribological properties of PPS composites has been carefully investigated and correlated under various sliding conditions. The results indicated that the tribological performance of PPS composites with double fibers is better than that of the composites with a single fiber, especially under severe conditions. Mechanism exploration suggests that a double‐fiber hybrid structure between a hard CF and a soft PFP fiber could tightly entrap the CF by fibril entanglement, thus preventing the CF from being stripped out of the matrix under the steel ring shearing force. Under optimized conditions, the average friction coefficient of composites with PFP fiber is only about 0.1 at 300 N load under 200 rpm, even lower than half of the average friction coefficient of the composites with PTFE powder under the same condition. Notably, compared to commercial split PFP fibers, the in‐situ formed PFP fibers with more uniform distribution significantly improve the tribological properties. This work open up a novel perspective for improving the tribological performance of composites by systematically regulating the microstructure of self‐lubricating fibrous additives.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>PFA is subject to in‐situ fibrillation during melt blending.</jats:list-item> <jats:list-item>Fibrous PFP effectively improves the tribological properties of PPS/CF composites.</jats:list-item> <jats:list-item>The in‐situ formed PFP fiber contributes to better tribological properties.</jats:list-item> <jats:list-item>The double‐fiber hybrid structure prevents the CF from being sheared out.</jats:list-item> <jats:list-item>The number of processing cycles affects the tribological properties.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"274 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study used molecular dynamics simulations to investigate the effects of the distribution angle of graphene oxide (GO) on the mechanical properties and non‐reciprocity of composite materials. The results of uniaxial tensile tests indicated that the mechanical properties of the composites are optimal when the distribution angles of GO are at 30° and 45°. The 30° model has an elastic modulus of 5.79 MPa, which is higher compared to the other models. The 80° model, however, has much lower mechanical properties, with a modulus of 1.42 MPa lower than the 30° model. Similarly, the 50° model also exhibits poorer mechanical properties with an elastic modulus of 4.42 MPa. Additionally, the 50° model is 24% lower than the 45° model. Through simulations of shearing in different directions and with different strain rates, it was found that the sensitivity of different GO distribution angles to strain rates varies. When the distribution angle is at 45°, the mechanical non‐reciprocity of the composite material is more pronounced.HighlightsExplored the mechanical properties of GO/PA66 composites at the molecular level.Revealed the microscopic mechanism of interaction between GO and PA66.The effect of GO distribution angle on uniaxial tensile properties was studied.Studied the mechanism of the effect of GO distribution angle on non‐reciprocity.
本研究利用分子动力学模拟研究了氧化石墨烯（GO）的分布角度对复合材料机械性能和非折回性的影响。单轴拉伸试验结果表明，当 GO 的分布角度为 30° 和 45° 时，复合材料的力学性能最佳。30° 模型的弹性模量为 5.79 兆帕，高于其他模型。然而，80° 模型的机械性能要低得多，模量比 30° 模型低 1.42 兆帕。同样，50° 模型的机械性能也较差，弹性模量为 4.42 兆帕。此外，50° 模型比 45° 模型低 24%。通过模拟不同方向和不同应变速率的剪切，发现不同的 GO 分布角对应变速率的敏感性各不相同。亮点 从分子水平探讨了 GO/PA66 复合材料的力学性能。揭示了 GO 与 PA66 之间相互作用的微观机理。研究了 GO 分布角对单轴拉伸性能的影响。研究了 GO 分布角对非折回性的影响机制。
{"title":"The influence of the distribution angle of graphene oxide on the mechanical properties and non‐reciprocity of composites","authors":"Zhangwei Xia, Zhangxin Guo, Qi Chen, Weijing Niu, Jianguo Liang, Gin Boay Chai, Wenyun Wu","doi":"10.1002/pc.29011","DOIUrl":"https://doi.org/10.1002/pc.29011","url":null,"abstract":"<jats:label/>This study used molecular dynamics simulations to investigate the effects of the distribution angle of graphene oxide (GO) on the mechanical properties and non‐reciprocity of composite materials. The results of uniaxial tensile tests indicated that the mechanical properties of the composites are optimal when the distribution angles of GO are at 30° and 45°. The 30° model has an elastic modulus of 5.79 MPa, which is higher compared to the other models. The 80° model, however, has much lower mechanical properties, with a modulus of 1.42 MPa lower than the 30° model. Similarly, the 50° model also exhibits poorer mechanical properties with an elastic modulus of 4.42 MPa. Additionally, the 50° model is 24% lower than the 45° model. Through simulations of shearing in different directions and with different strain rates, it was found that the sensitivity of different GO distribution angles to strain rates varies. When the distribution angle is at 45°, the mechanical non‐reciprocity of the composite material is more pronounced.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>Explored the mechanical properties of GO/PA66 composites at the molecular level.</jats:list-item> <jats:list-item>Revealed the microscopic mechanism of interaction between GO and PA66.</jats:list-item> <jats:list-item>The effect of GO distribution angle on uniaxial tensile properties was studied.</jats:list-item> <jats:list-item>Studied the mechanism of the effect of GO distribution angle on non‐reciprocity.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"118 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study meticulously investigated the effect of two carbon allotrope nanofillers, two‐dimensional graphene nanoplatelets (GnPs) and one‐dimensional multi‐wall carbon nanotubes (MWCNTs) individually, at various loadings on the kinetics of curing of the epoxy (EP)/vinyl ester (VE) based interpenetrating polymer network (IPN) system, with a mass ratio of 1:1. The IPN system is including a liquid epoxy resin based on bisphenol A which has been cured by methyltetrahydrophthalic anhydride (MTHPA) in the presence of 1‐methyl imidazole (Mi) as an accelerator and a vinyl ester resin based on bisphenol A which has been cured by methyl ethyl ketone peroxide (MEKP). The curing behavior of all prepared nanocomposites under non‐isothermal conditions was studied using DSC at four heating rates. Two different isoconversional approaches were applied to evaluate the reaction kinetics, that is, the Friedman and the advanced Vyazovkin methods. The obtained activation energy curves for all samples revealed a complex curing behavior involving three stages: early IPN stage, IPN growth stage, and late IPN stage. Then, the activation energy values for each reaction step were determined based on the Friedman method. The presence of GnPs showed no catalytic effect on the reaction of VE with MEKP. In contrast, incorporating MWCNT nanoparticles considerably decreases the activation energy values of the reaction of ring opening of epoxides with MTHPA‐Mi and the reaction of esterification of the hydroxyl groups of VE with MTHPA.HighlightsMWCNTs reduce activation energy in curing reactions for EP/MTHPA‐Mi and VE/MTHPA.GnPs do not catalyze VE/MEKP reaction unlike MWCNTs.Combining MWCNTs and GnPs enhances properties of IPN nanocomposites.Curing process includes early, growth, and late IPN stages impacting activation energy.SEM analysis reveals better dispersion of GnPs in IPN nanocomposites with MWCNTs.
{"title":"The effects of 1D multi‐wall carbon nanotubes and 2D graphene nanoplatelets on curing behavior of epoxy/vinyl ester interpenetrating polymer network nanocomposites","authors":"Afrooz Molaei, Ali Jannesari","doi":"10.1002/pc.28970","DOIUrl":"https://doi.org/10.1002/pc.28970","url":null,"abstract":"<jats:label/>This study meticulously investigated the effect of two carbon allotrope nanofillers, two‐dimensional graphene nanoplatelets (GnPs) and one‐dimensional multi‐wall carbon nanotubes (MWCNTs) individually, at various loadings on the kinetics of curing of the epoxy (EP)/vinyl ester (VE) based interpenetrating polymer network (IPN) system, with a mass ratio of 1:1. The IPN system is including a liquid epoxy resin based on bisphenol A which has been cured by methyltetrahydrophthalic anhydride (MTHPA) in the presence of 1‐methyl imidazole (Mi) as an accelerator and a vinyl ester resin based on bisphenol A which has been cured by methyl ethyl ketone peroxide (MEKP). The curing behavior of all prepared nanocomposites under non‐isothermal conditions was studied using DSC at four heating rates. Two different isoconversional approaches were applied to evaluate the reaction kinetics, that is, the Friedman and the advanced Vyazovkin methods. The obtained activation energy curves for all samples revealed a complex curing behavior involving three stages: early IPN stage, IPN growth stage, and late IPN stage. Then, the activation energy values for each reaction step were determined based on the Friedman method. The presence of GnPs showed no catalytic effect on the reaction of VE with MEKP. In contrast, incorporating MWCNT nanoparticles considerably decreases the activation energy values of the reaction of ring opening of epoxides with MTHPA‐Mi and the reaction of esterification of the hydroxyl groups of VE with MTHPA.Highlights<jats:list list-type=\"bullet\"> <jats:list-item>MWCNTs reduce activation energy in curing reactions for EP/MTHPA‐Mi and VE/MTHPA.</jats:list-item> <jats:list-item>GnPs do not catalyze VE/MEKP reaction unlike MWCNTs.</jats:list-item> <jats:list-item>Combining MWCNTs and GnPs enhances properties of IPN nanocomposites.</jats:list-item> <jats:list-item>Curing process includes early, growth, and late IPN stages impacting activation energy.</jats:list-item> <jats:list-item>SEM analysis reveals better dispersion of GnPs in IPN nanocomposites with MWCNTs.</jats:list-item> </jats:list>","PeriodicalId":20375,"journal":{"name":"Polymer Composites","volume":"124 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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