Pub Date : 2026-01-26DOI: 10.1016/j.jcomc.2026.100700
Morteza Saadatmorad , Nicholas Fantuzzi , Pietro Russo
This paper introduces Legendre wavelets as a novel wavelet type and explores their effectiveness in detecting damage in carbon-epoxy composite beams. These wavelets are generated by differentiating the first derivative of Legendre functions on a ten-digit grid using finite difference methods, resulting in three versions with seven, five, and three sampling points. The Legendre wavelet functions with five and three sampling points are computed. Carbon-epoxy laminated composite beam mode shapes serve as the input signal for a Legendre wavelet transform. Numerical and experimental studies validate the practical applicability of these wavelets for damage detection. Results demonstrate that all Legendre wavelet functions are suitable for damage detection in laminated composite beams. Especially, those derived from higher-degree Legendre polynomials exhibit superior performance.
{"title":"Introducing Legendre wavelet functions for damage detection in laminated composite beams","authors":"Morteza Saadatmorad , Nicholas Fantuzzi , Pietro Russo","doi":"10.1016/j.jcomc.2026.100700","DOIUrl":"10.1016/j.jcomc.2026.100700","url":null,"abstract":"<div><div>This paper introduces Legendre wavelets as a novel wavelet type and explores their effectiveness in detecting damage in carbon-epoxy composite beams. These wavelets are generated by differentiating the first derivative of Legendre functions on a ten-digit grid using finite difference methods, resulting in three versions with seven, five, and three sampling points. The Legendre wavelet functions with five and three sampling points are computed. Carbon-epoxy laminated composite beam mode shapes serve as the input signal for a Legendre wavelet transform. Numerical and experimental studies validate the practical applicability of these wavelets for damage detection. Results demonstrate that all Legendre wavelet functions are suitable for damage detection in laminated composite beams. Especially, those derived from higher-degree Legendre polynomials exhibit superior performance.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100700"},"PeriodicalIF":7.0,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077398","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}
Pub Date : 2026-01-22DOI: 10.1016/j.jcomc.2026.100702
Atiyeh Adelinia , Aleksey Yerokhin , David T.A. Matthews , Laurent Warnet , Matthijn B. de Rooij , Jamal Seyyed Monfared Zanjani
This study investigates the contribution of different bonding mechanisms to the fracture toughness of aluminium alloy and glass-fibre polyamide 6 (GFPA6) joints as influenced by surface treatments. Aluminium substrates were treated by two grit blasting conditions, two annealing durations, and a plasma electrolytic oxidation (PEO) coating process, yielding surfaces with distinct morphologies and chemistries. Surface morphology, chemistry, and wettability of the treated aluminium surfaces were characterised. Afterwards, the aluminium-GFPA6 joints were fabricated via hot pressing and evaluated by mandrel peel testing to determine fracture toughness, complemented by interfacial and fractographic analyses. All aluminium surfaces showed wettability by PA6 with contact angles <90°. Annealing increased surface free energy and improved interfacial interactions, while grit blasting and PEO increased surface area and enabled mechanical interlocking. Compared to the as-received surface, fracture toughness increased up to ∼5-fold by annealing, ∼7-fold by grit blasting, and ∼9-fold by PEO. The superior performance of PEO-treated joints is attributed to the highly porous and irregular coating morphology, which maximises interfacial area, and promotes both mechanical interlocking and interfacial interactions.
{"title":"Bonding mechanisms in directly bonded aluminium and glass-fibre polyamide 6 hybrids","authors":"Atiyeh Adelinia , Aleksey Yerokhin , David T.A. Matthews , Laurent Warnet , Matthijn B. de Rooij , Jamal Seyyed Monfared Zanjani","doi":"10.1016/j.jcomc.2026.100702","DOIUrl":"10.1016/j.jcomc.2026.100702","url":null,"abstract":"<div><div>This study investigates the contribution of different bonding mechanisms to the fracture toughness of aluminium alloy and glass-fibre polyamide 6 (GFPA6) joints as influenced by surface treatments. Aluminium substrates were treated by two grit blasting conditions, two annealing durations, and a plasma electrolytic oxidation (PEO) coating process, yielding surfaces with distinct morphologies and chemistries. Surface morphology, chemistry, and wettability of the treated aluminium surfaces were characterised. Afterwards, the aluminium-GFPA6 joints were fabricated via hot pressing and evaluated by mandrel peel testing to determine fracture toughness, complemented by interfacial and fractographic analyses. All aluminium surfaces showed wettability by PA6 with contact angles <90°. Annealing increased surface free energy and improved interfacial interactions, while grit blasting and PEO increased surface area and enabled mechanical interlocking. Compared to the as-received surface, fracture toughness increased up to ∼5-fold by annealing, ∼7-fold by grit blasting, and ∼9-fold by PEO. The superior performance of PEO-treated joints is attributed to the highly porous and irregular coating morphology, which maximises interfacial area, and promotes both mechanical interlocking and interfacial interactions.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100702"},"PeriodicalIF":7.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037334","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}
Pub Date : 2026-01-22DOI: 10.1016/j.jcomc.2026.100701
Erik Kappel , Ronald Klomp
Double–Double (DD) laminates provide unique design and manufacturing opportunities. This makes them a promising challenger for conventional laminates used in aerospace composite parts today. DD laminates benefit from an effect denoted as ’homogenization’, which leads to a mechanical behavior known from orthotropic laminates, without complex coupling effects, although DD laminates have asymmetric ply-stacking sequences. Manufacturing aspects and particularly the topic of process-induced distortions (PID) have attracted little attention in DD context. The present article is dedicated to this topic. It outlines why some DD laminates show warpage and twist after a typical 180°C curing process, while others remain almost flat. Hence, the article provides practical guidance for selecting building-block stacking sequences, which induce minimum warpage.
{"title":"Why selected autoclave-cured Double–Double laminates are particular prone to warpage","authors":"Erik Kappel , Ronald Klomp","doi":"10.1016/j.jcomc.2026.100701","DOIUrl":"10.1016/j.jcomc.2026.100701","url":null,"abstract":"<div><div>Double–Double (DD) laminates provide unique design and manufacturing opportunities. This makes them a promising challenger for conventional laminates used in aerospace composite parts today. DD laminates benefit from an effect denoted as ’homogenization’, which leads to a mechanical behavior known from orthotropic laminates, without complex coupling effects, although DD laminates have asymmetric ply-stacking sequences. Manufacturing aspects and particularly the topic of process-induced distortions (PID) have attracted little attention in DD context. The present article is dedicated to this topic. It outlines why some DD laminates show warpage and twist after a typical 180°C curing process, while others remain almost flat. Hence, the article provides practical guidance for selecting building-block stacking sequences, which induce minimum warpage.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100701"},"PeriodicalIF":7.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077396","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}
Mycelium biocomposites (MBCs) offer a sustainable, zero-waste alternative for non-structural construction materials. This study investigated the influence of substrate morphology on MBC properties by using two novel waste streams: fibrous recycled paper (RP) alone and a particulate co-substrate of high-content spent coffee grounds (SCG) mixed with rice husks (RH), mainly for non-structural construction components (road guidepost). Three compositions of MBCs were fabricated: (MBC/RP, MBC/SCG50-RH50, MBC/SCG80-RH20). Compression test, water absorption, and fire resistance performance were characterized alongside microstructural analyses via SEM and X-ray μCT. Experimental results disclosed that substrate morphology critically governs MBC performance. MBC/RP achieved the highest compressive strength (1.67 MPa) at high strain 0.58 mm/mm and an excellent V-0 fire rating due to dense mycelial entanglement with fibrous substrate and protective char layer formation. Conversely, MBC/SCG-RH groups exhibited lower strength (0.25–0.46 MPa) and fire resistance. Nevertheless, MBC/SCG80-RH20 achieved the highest stiffness (2.41 MPa) and exhibited brittle behavior, linked to SCG-RH particle interlocking that created a closed-pore structure (58.27–61.61 % porosity) and significantly lower water uptake (130 %) than open-pored MBC/RP (272 % water uptake and 52.87 % porosity). Accordingly, MBC/SCG-RH groups are better suited for biodegradable packaging while MBC/RP was the only candidate satisfying non-structural construction materials specifications. Despite susceptible to high moisture, MBC/RP maintained structural integrity in dry environments, demonstrating a functional lifespan exceeding three months. The practical feasibility was validated by successfully fabricating an initial 1:4 scale MBC/RP road guidepost prototype. These findings confirm the potential of tailoring waste resources to meet mechanical, fire performance, and degradability for non-load-bearing outdoor applications.
{"title":"Mycelium biocomposites from spent coffee grounds, rice husk, and recycled paper for temporary eco-road guideposts: Microstructure-property relationships, fire resistance, and outdoor durability","authors":"Pimpet Sratong-on , Supaluk Prapan , Warangkana Chaithanee , Kanyarat Puttawongsakul , Sutep Joy-A-Ka","doi":"10.1016/j.jcomc.2026.100699","DOIUrl":"10.1016/j.jcomc.2026.100699","url":null,"abstract":"<div><div>Mycelium biocomposites (MBCs) offer a sustainable, zero-waste alternative for non-structural construction materials. This study investigated the influence of substrate morphology on MBC properties by using two novel waste streams: fibrous recycled paper (RP) alone and a particulate co-substrate of high-content spent coffee grounds (SCG) mixed with rice husks (RH), mainly for non-structural construction components (road guidepost). Three compositions of MBCs were fabricated: (MBC/RP, MBC/SCG50-RH50, MBC/SCG80-RH20). Compression test, water absorption, and fire resistance performance were characterized alongside microstructural analyses via SEM and X-ray μCT. Experimental results disclosed that substrate morphology critically governs MBC performance. MBC/RP achieved the highest compressive strength (1.67 MPa) at high strain 0.58 mm/mm and an excellent V-0 fire rating due to dense mycelial entanglement with fibrous substrate and protective char layer formation. Conversely, MBC/SCG-RH groups exhibited lower strength (0.25–0.46 MPa) and fire resistance. Nevertheless, MBC/SCG80-RH20 achieved the highest stiffness (2.41 MPa) and exhibited brittle behavior, linked to SCG-RH particle interlocking that created a closed-pore structure (58.27–61.61 % porosity) and significantly lower water uptake (130 %) than open-pored MBC/RP (272 % water uptake and 52.87 % porosity). Accordingly, MBC/SCG-RH groups are better suited for biodegradable packaging while MBC/RP was the only candidate satisfying non-structural construction materials specifications. Despite susceptible to high moisture, MBC/RP maintained structural integrity in dry environments, demonstrating a functional lifespan exceeding three months. The practical feasibility was validated by successfully fabricating an initial 1:4 scale MBC/RP road guidepost prototype. These findings confirm the potential of tailoring waste resources to meet mechanical, fire performance, and degradability for non-load-bearing outdoor applications.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100699"},"PeriodicalIF":7.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077397","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}
Pub Date : 2026-01-17DOI: 10.1016/j.jcomc.2026.100698
Sharath Christy Anand, Amir Hajdarevic, Xiangfan Fang
This paper presents experimental study and FE prediction of hybrid steel-PA6 long fiber thermoplastic (LFT) structures under dynamic three-point bending. Using the novel hybrid forming process, steel sheet and LFT were simultaneously formed and joined. Together with hybrid U-profile, pure LFT and steel U-profiles were manufactured and tested. Results show that specific energy absorption (SEA) of hybrid profiles was 57 % higher than the combined SEA of the individual materials, due to contribution of fractured LFT material in the closed section.
Detailed FE framework was followed incorporating material characterization for Steel, LFT and adhesive into the FE simulation. Process simulations were performed and simulated fiber orientations were validated against XµCT scans and mapped onto LS-Dyna mesh. Dynamic three-point bending tests were replicated in FE simulations using the Johnson-Cook failure criterion for LFT materials. simulation results for pure steel and pure LFT profiles aligned well with experimental data. Simulations of the hybrid U-profile revealed discrepancies in energy absorption. Further analysis indicated that part of the energy was accounted for through element failure and frictional contact, which contributed to the observed deviation. This combined approach replicates experimental behavior and also provides insight into how hybrid structures distribute and absorb energy under dynamic loading.
{"title":"Experimental analyses and numerical modelling of dynamic three point bending behavior of hybrid formed steel-PA6LFT40 structures","authors":"Sharath Christy Anand, Amir Hajdarevic, Xiangfan Fang","doi":"10.1016/j.jcomc.2026.100698","DOIUrl":"10.1016/j.jcomc.2026.100698","url":null,"abstract":"<div><div>This paper presents experimental study and FE prediction of hybrid steel-PA6 long fiber thermoplastic (LFT) structures under dynamic three-point bending. Using the novel hybrid forming process, steel sheet and LFT were simultaneously formed and joined. Together with hybrid U-profile, pure LFT and steel U-profiles were manufactured and tested. Results show that specific energy absorption (SEA) of hybrid profiles was 57 % higher than the combined SEA of the individual materials, due to contribution of fractured LFT material in the closed section.</div><div>Detailed FE framework was followed incorporating material characterization for Steel, LFT and adhesive into the FE simulation. Process simulations were performed and simulated fiber orientations were validated against XµCT scans and mapped onto LS-Dyna mesh. Dynamic three-point bending tests were replicated in FE simulations using the Johnson-Cook failure criterion for LFT materials. simulation results for pure steel and pure LFT profiles aligned well with experimental data. Simulations of the hybrid U-profile revealed discrepancies in energy absorption. Further analysis indicated that part of the energy was accounted for through element failure and frictional contact, which contributed to the observed deviation. This combined approach replicates experimental behavior and also provides insight into how hybrid structures distribute and absorb energy under dynamic loading.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100698"},"PeriodicalIF":7.0,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037335","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 production of virgin carbon fiber (vCF) is an energy-intensive process. The recycled carbon fiber (rCF) plays a crucial role by reducing energy consumption, lowering environmental impact, and promoting circularity within the composite materials industry. This study explores the recycling potential of prepreg carbon fiber waste and discarded automotive bumpers for producing composites from waste. The CFRP waste was recycled through a controlled thermal process and the resulting weight loss behavior obtained via a muffle furnace was evaluated using a design of experiments and analysis of variance. Optimization identified 500 °C with a 60 min holding time as the most effective condition, yielding clean rCF with minimal degradation and a residual mass of approximately 51.74 wt.%. The rCF was compounded with shredded car bumper at 0, 5, and 10 wt.% fiber contents. Incorporation of 10 wt.% rCF increased the tensile strength from 14.12 MPa to 19.40 MPa (+37.4%) and the flexural strength from 23.72 MPa to 29.12 MPa (+22.6%), whereas impact strength decreased from 269.12 J/m to 66.11 J/m (−75.4%) due to reduced energy absorption. The 5 wt.% rCF composites exhibited the highest tensile modulus of 0.69 GPa, indicating superior stiffness, while the 10 wt.% rCF composites demonstrated a slightly lower modulus of 0.53 GPa (−23.2%) but higher strength and hardness, suitable for load-bearing and wear-resistant applications. These results demonstrate that both CFRP and automotive plastic wastes can be effectively recycled into value added composites with tunable mechanical properties, supporting the circular economy and reducing energy intensive vCF.
{"title":"Recycled composite materials from plastic parts of end-of-life vehicles mixed with recycled carbon fiber from automotive manufacturing waste","authors":"Nuttakorn Wongkhuenkaew, Ponlapath Tipboonsri, Supaaek Pramoonmak, Boonsong Chongkolnee, Anin Memon","doi":"10.1016/j.jcomc.2026.100696","DOIUrl":"10.1016/j.jcomc.2026.100696","url":null,"abstract":"<div><div>The production of virgin carbon fiber (vCF) is an energy-intensive process. The recycled carbon fiber (rCF) plays a crucial role by reducing energy consumption, lowering environmental impact, and promoting circularity within the composite materials industry. This study explores the recycling potential of prepreg carbon fiber waste and discarded automotive bumpers for producing composites from waste. The CFRP waste was recycled through a controlled thermal process and the resulting weight loss behavior obtained via a muffle furnace was evaluated using a design of experiments and analysis of variance. Optimization identified 500 °C with a 60 min holding time as the most effective condition, yielding clean rCF with minimal degradation and a residual mass of approximately 51.74 wt.%. The rCF was compounded with shredded car bumper at 0, 5, and 10 wt.% fiber contents. Incorporation of 10 wt.% rCF increased the tensile strength from 14.12 MPa to 19.40 MPa (+37.4%) and the flexural strength from 23.72 MPa to 29.12 MPa (+22.6%), whereas impact strength decreased from 269.12 J/m to 66.11 J/m (−75.4%) due to reduced energy absorption. The 5 wt.% rCF composites exhibited the highest tensile modulus of 0.69 GPa, indicating superior stiffness, while the 10 wt.% rCF composites demonstrated a slightly lower modulus of 0.53 GPa (−23.2%) but higher strength and hardness, suitable for load-bearing and wear-resistant applications. These results demonstrate that both CFRP and automotive plastic wastes can be effectively recycled into value added composites with tunable mechanical properties, supporting the circular economy and reducing energy intensive vCF.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100696"},"PeriodicalIF":7.0,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976935","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}
Pub Date : 2026-01-05DOI: 10.1016/j.jcomc.2026.100695
Andrii Hrechuk , Rachid M’Saoubi , Thomas Melin , Stefan Frejd , Pär Nordberg , Lennart Karlsson , Per Alm , Vyacheslav Kryzhanivskyy , Volodymyr Bushlya
Carbon Fibre-Reinforced Polymers (CFRP) are a fast growing market of high performance materials and components. Thermally induced damage during machining processes such as drilling or routing are among the limiting factors for product quality, yet accurate temperature measurement remains challenging. This study develops a methodology which combines machinable thermocouples and IR thermometry techniques to measure the temperature of the drill. Proposed combination, further enhanced by careful synchronization, timestamping and postprocessing, allows fine resolution analysis of local temperature along the cutting edges. The study compares three different designs of drills and the impact of their geometry and wear on generated temperature. The results indicate that positive rake angle is a favourable geometric feature which allows to maintain lower local temperature of 129–142 °C in unworn state.
{"title":"Effect of tool geometry and flank wear on drill temperature during CFRP machining","authors":"Andrii Hrechuk , Rachid M’Saoubi , Thomas Melin , Stefan Frejd , Pär Nordberg , Lennart Karlsson , Per Alm , Vyacheslav Kryzhanivskyy , Volodymyr Bushlya","doi":"10.1016/j.jcomc.2026.100695","DOIUrl":"10.1016/j.jcomc.2026.100695","url":null,"abstract":"<div><div>Carbon Fibre-Reinforced Polymers (CFRP) are a fast growing market of high performance materials and components. Thermally induced damage during machining processes such as drilling or routing are among the limiting factors for product quality, yet accurate temperature measurement remains challenging. This study develops a methodology which combines machinable thermocouples and IR thermometry techniques to measure the temperature of the drill. Proposed combination, further enhanced by careful synchronization, timestamping and postprocessing, allows fine resolution analysis of local temperature along the cutting edges. The study compares three different designs of drills and the impact of their geometry and wear on generated temperature. The results indicate that positive rake angle is a favourable geometric feature which allows to maintain lower local temperature of 129–142 °C in unworn state.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100695"},"PeriodicalIF":7.0,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925591","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}
Pub Date : 2026-01-02DOI: 10.1016/j.jcomc.2025.100690
Ioannis Katsivalis , Rosemere de Araujo Alves Lima , Florence Moreau , Leif E. Asp , Sofia Teixeira de Freitas
Tow-Based Discontinuous Composites (TBDCs) are a new class of composite materials that combine high strength and stiffness with in-plane isotropy making them of interest in high-end structural applications. Despite their potential, efficient connection methods are currently lacking and the adhesive bonding behaviour of TBDC structures remains unexplored. This work, therefore, seeks to address this gap by analysing the quasi-static performance of TBDC adhesive joints under mode I loading condition. Double Cantilever Beam (DCB) tests were performed using two adhesives with contrasting toughness levels: a moderate (∼600 J/m 2) and a high toughness adhesive (> 2400 J/m2). When a moderate-toughness adhesive was used, a combination of cohesive failure and composite damage was observed, with only a small scatter in the experimental results. In contrast, the use of the high-toughness adhesive led to a shift in damage mechanisms towards the composite micro-architecture, resulting in fracture toughness values in the region of 800 J/m2, with a larger experimental scatter. Acoustic Emission analysis identified matrix cracking and fibre/matrix debonding as the dominant damage mechanisms. These findings were validated by the post-mortem fractography analysis via Scanning Electron Microscopy. This work therefore provides the first detailed analysis of the damage mechanism in adhesively bonded TBDCs, which have potential in aerospace and automotive applications.
{"title":"Damage mechanisms of adhesively bonded joints of thin tow-based discontinuous composites","authors":"Ioannis Katsivalis , Rosemere de Araujo Alves Lima , Florence Moreau , Leif E. Asp , Sofia Teixeira de Freitas","doi":"10.1016/j.jcomc.2025.100690","DOIUrl":"10.1016/j.jcomc.2025.100690","url":null,"abstract":"<div><div>Tow-Based Discontinuous Composites (TBDCs) are a new class of composite materials that combine high strength and stiffness with in-plane isotropy making them of interest in high-end structural applications. Despite their potential, efficient connection methods are currently lacking and the adhesive bonding behaviour of TBDC structures remains unexplored. This work, therefore, seeks to address this gap by analysing the quasi-static performance of TBDC adhesive joints under mode I loading condition. Double Cantilever Beam (DCB) tests were performed using two adhesives with contrasting toughness levels: a moderate (∼600 J/m <sup>2</sup>) and a high toughness adhesive (> 2400 J/m<sup>2</sup>). When a moderate-toughness adhesive was used, a combination of cohesive failure and composite damage was observed, with only a small scatter in the experimental results. In contrast, the use of the high-toughness adhesive led to a shift in damage mechanisms towards the composite micro-architecture, resulting in fracture toughness values in the region of 800 J/m<sup>2</sup>, with a larger experimental scatter. Acoustic Emission analysis identified matrix cracking and fibre/matrix debonding as the dominant damage mechanisms. These findings were validated by the post-mortem fractography analysis via Scanning Electron Microscopy. This work therefore provides the first detailed analysis of the damage mechanism in adhesively bonded TBDCs, which have potential in aerospace and automotive applications.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100690"},"PeriodicalIF":7.0,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925644","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}
A continuous fibreglass (CFG)-reinforced polyamide 6 (PA6) sandwich structure with self-sensing capabilities was developed by confining multi-walled carbon nanotubes (MWCNTs) within the material volume through a step-by-step process involving a) 3D printing of specimens with a designed porous structure, b) embedding MWCNTs onto the surface of polyamide pores swollen with acid-formic solutions containing various filler contents, and c) hot-pressing the resulting specimens to close the porosity. Sandwiched specimens, designed with top-bottom skins at control layup (no reinforcement CFG, namely “noGF”), the quasi-isotropic (with CFG oriented 0/45/90/-45°s, namely “qiGF”), and the longitudinal layup (with CFG oriented at 0°, namely “longGF”) were subjected to steady and cyclic three-point bending tests and mechanical and piezoresistive characterized. The results show a correlation between applied strain and measured electrical resistance, with a gauge factor (GF) of 23 at a strain of 0.83% for the sample containing 0.05 wt% MWCNTs. The fibre reinforcement, together with the porous sandwich design, proved effective in reducing electrical hysteresis and improving measurement repeatability. The sample containing 0.05 wt% of MWCNTs and longGF shows a significant improvement in sensing performance. These findings confirm that confining MWCNTs within 3D-printed PA6 sandwich structures is an effective strategy for enhancing the piezoresistivity.
{"title":"Confinement of MWCNTs in PA6 3D-printed fibreglass-reinforced composites to enhance piezoresistive properties","authors":"Nicolò Geneletti , Gennaro Rollo , Luca Michele Martulli , Andrea Bernasconi , Alfredo Ronca , Andrea Sorrentino , Marino Lavorgna","doi":"10.1016/j.jcomc.2025.100692","DOIUrl":"10.1016/j.jcomc.2025.100692","url":null,"abstract":"<div><div>A continuous fibreglass (CFG)-reinforced polyamide 6 (PA6) sandwich structure with self-sensing capabilities was developed by confining multi-walled carbon nanotubes (MWCNTs) within the material volume through a step-by-step process involving a) 3D printing of specimens with a designed porous structure, b) embedding MWCNTs onto the surface of polyamide pores swollen with acid-formic solutions containing various filler contents, and c) hot-pressing the resulting specimens to close the porosity. Sandwiched specimens, designed with top-bottom skins at control layup (no reinforcement CFG, namely “noGF”), the quasi-isotropic (with CFG oriented 0/45/90/-45°s, namely “qiGF”), and the longitudinal layup (with CFG oriented at 0°, namely “longGF”) were subjected to steady and cyclic three-point bending tests and mechanical and piezoresistive characterized. The results show a correlation between applied strain and measured electrical resistance, with a gauge factor (GF) of 23 at a strain of 0.83% for the sample containing 0.05 wt% MWCNTs. The fibre reinforcement, together with the porous sandwich design, proved effective in reducing electrical hysteresis and improving measurement repeatability. The sample containing 0.05 wt% of MWCNTs and longGF shows a significant improvement in sensing performance. These findings confirm that confining MWCNTs within 3D-printed PA6 sandwich structures is an effective strategy for enhancing the piezoresistivity.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100692"},"PeriodicalIF":7.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925590","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}
Pub Date : 2026-01-01DOI: 10.1016/j.jcomc.2025.100689
Roham Rafiee, Ali Shahcheraghi
This research focuses on extending an analytical solution for the stress analysis of composite pipes and pressure vessels under internal loading based on 3D-elasticity approach. In terms of engineering applications, the developed model can be applied to any arbitrary lay-up configuration of pipes or vessels without any limitation on the number of layers. Namely, the main drawback of the previously developed analytical method which made it applicable to the case of 4-layer pipes/vessels is resolved. Ensuring the accuracy of the developed model, the results from the extended analytical method, classical lamination theory, and finite element analysis are benchmarked against one another. A parametric study is also done to analyze the influence of pipe diameter and thickness on the results. Contrasting the two theoretical methods over various thickness and radius, a better understanding of the functionality of these methods are acquired.
{"title":"On the stress analysis of composite pipes and vessels subjected to internal pressure","authors":"Roham Rafiee, Ali Shahcheraghi","doi":"10.1016/j.jcomc.2025.100689","DOIUrl":"10.1016/j.jcomc.2025.100689","url":null,"abstract":"<div><div>This research focuses on extending an analytical solution for the stress analysis of composite pipes and pressure vessels under internal loading based on 3D-elasticity approach. In terms of engineering applications, the developed model can be applied to any arbitrary lay-up configuration of pipes or vessels without any limitation on the number of layers. Namely, the main drawback of the previously developed analytical method which made it applicable to the case of 4-layer pipes/vessels is resolved. Ensuring the accuracy of the developed model, the results from the extended analytical method, classical lamination theory, and finite element analysis are benchmarked against one another. A parametric study is also done to analyze the influence of pipe diameter and thickness on the results. Contrasting the two theoretical methods over various thickness and radius, a better understanding of the functionality of these methods are acquired.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"19 ","pages":"Article 100689"},"PeriodicalIF":7.0,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925568","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号