{"title":"Data-driven prediction of failure loads in low-cost FRP-confined reinforced concrete beams","authors":"Shabbir Ali Talpur , Phromphat Thansirichaisree , Weerachai Anotaipaiboon , Hisham Mohamad , Mingliang Zhou , Ali Ejaz , Qudeer Hussain , Panumas Saingam , Preeda Chaimahawan","doi":"10.1016/j.jcomc.2025.100579","DOIUrl":"10.1016/j.jcomc.2025.100579","url":null,"abstract":"<div><div>This study investigates the application of machine learning (ML) models to predict the ultimate failure load of reinforced concrete (RC) beams confined with low-cost fiber-reinforced polymers (FRP), relatively underexplored area. A dataset of 100 samples, including beams designed to fail in flexure and shear, was compiled from literature and experimental testing. Four ML models—XGBoost, Random Forest (RF), Neural Network (NN), and Decision Tree (DT)—were evaluated using k-fold cross-validation with performance metrics such as Mean Absolute Error (MAE), Mean Squared Error (MSE), Root Mean Squared Error (RMSE), and R². XGBoost outperformed the other models, achieving the highest R² of 0.96 and the lowest RMSE of 12.81, while SHAP analysis identified beam height, bottom rebar strength, and beam width as key predictors. These results highlight the effectiveness of ensemble methods for predicting failure loads in RC beams and provide insights into the most influential features affecting structural performance.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"17 ","pages":"Article 100579"},"PeriodicalIF":5.3,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Surface tailored spent coffee ground derived carbon reinforced waste HDPE composites for 3D printing application","authors":"Sushrisangita Sahoo, Abhinav Yadav, Vijaya Rangari","doi":"10.1016/j.jcomc.2025.100570","DOIUrl":"10.1016/j.jcomc.2025.100570","url":null,"abstract":"<div><div>The serious impact of plastic waste on environmental pollution and climate change led to new strategies like recycle, reuse, reduce concept. This work presents a unique sustainable approach of developing filament composites with improved thermal and mechanical properties by mixing the plastic waste (i.e. waste Walmart bag, High Density Polyethylene (HDPE)) and surface engineered spent coffee ground (SCG) waste derived carbon. Carbon as filler materials were obtained by pyrolyzing the SCG waste. As the biomass derived carbon generally has inert surface properties, it causes poor compatibility between the filler and polymer matrix yielding inferior thermal and mechanical properties of the composites. So, the properties of pyrolyzed carbon in the present work were tailored by SF<sub>6</sub> plasma treatment at different time durations. The surface functionalization of carbon materials and optimized plasma treatment time were analyzed from different characterizations. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) reveals 15 min plasma treatment carbon is the optimized one with highest fluorination and semi-ionic C-F bonding. Due to the highest fluorination, the I<sub>D</sub>/I<sub>G</sub> ratio i.e. the defect density is found to be maximum for 15 min plasma treated carbon from the Raman spectra. The 15 min plasma treated carbon with highest fluorine functionalization as a filler exhibits 33.8 % and 13.97 % improvement in tensile modulus and tensile strength in comparison to neat HDPE matrix. The feasibility test of filament composites for 3D printing suggests its application potentiality in Material extrusion (MEX) 3D printing.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100570"},"PeriodicalIF":5.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143488303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Less is more: Optimised fire performance in glass fibre-reinforced polybutylene terephthalate laminates with concentrated flame retardant top layer","authors":"Weronika Tabaka, Bernhard Schartel","doi":"10.1016/j.jcomc.2025.100577","DOIUrl":"10.1016/j.jcomc.2025.100577","url":null,"abstract":"<div><div>To achieve optimum fire performance while maintaining mechanical integrity, flame retardants (FR) were strategically concentrated in the surface layer of a two-layer glass fibre-reinforced polybutylene terephthalate (PBT) laminate structure. Three potentially synergistic FR systems were selected to improve the fire performance of glass fibre-reinforced PBT: boehmite (AlOOH) with melamine polyzinc phosphate (MPZnP), aluminium diethyl phosphinates (AlPi) with melamine cyanurate (MC), and expandable graphite (EG) with melamine polyphosphate (MPP). Limited Oxygen Index (LOI) and UL-94 testing highlighted the influence of laminate architecture on flammability. The cone calorimeter results showed that increasing the FR concentration in the top layer significantly reduced both the peak heat release rate (PHRR) and the maximum average rate of heat emission (MARHE), with improvements depending on the specific FR system used. The laminate L-PBT/GF/AlOOH/MPZnP with a 2:2 thickness ratio showed outstanding performance, achieving a 45 % reduction in MARHE compared to composites with uniform FR distribution. This result showcases the superior thermal barrier properties and synergistic behaviour of AlOOH and MPZnP. The fire performance of laminates containing AlPi and MC was strongly influenced by the distribution and concentration of AlPi/MC. The EG/MPP system was found to be highly effective, forming a protective intumescent layer that significantly reduced both HRR and MARHE, demonstrating the effectiveness of strategically concentrating FR in the top layer.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100577"},"PeriodicalIF":5.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhanced thermal insulation performance of silica aerogel composites through infrared opacifier integration for high-temperature applications","authors":"Beatriz Merillas , Cláudio M.R. Almeida , Tomás Enrique Gómez Álvarez-Arenas , Miguel Ángel Rodríguez-Pérez , Luisa Durães","doi":"10.1016/j.jcomc.2025.100573","DOIUrl":"10.1016/j.jcomc.2025.100573","url":null,"abstract":"<div><div>The inclusion of different fillers in silica aerogels reinforced by a reticulated polyurethane skeleton, allows for the development of a strategy to obtain composites with superior characteristics. Different fillers (TiO<sub>2</sub>, GO, SiC) and contents (0.2, 0.5 and 1.0 wt.%) were explored, analyzing their effects on the porous structures, mechanical stiffness and thermal conductivity of the composites. These exhibited low densities, reduced shrinkage, and high specific surface areas of approximately 550 m<sup>2</sup>/g. The incorporated fillers were homogeneously dispersed, leading to a general decrease in the mean pore size. Despite observing a slight reduction in the elastic modulus with respect to the non-doped composite, the benefits of this strategy are twofold; the composites can withstand strains above 80 % without breaking, significantly improving the mechanical stability when compared to non-reinforced silica aerogels, and while achieving high resilience. Additionally, enhanced thermal insulating performance was found for some materials. After analyzing the heat transfer contributions, the optimum particle contents for an improved thermal insulation were identified (1.0 wt.% TiO<sub>2</sub> and 0.2 wt.% SiC), leading to an effective reduction of the radiation term and reaching overall reductions of 10 and 6.5 % at 100 °C. Therefore, the silica aerogel-based composites herein produced represent a step forward in their usability and versatility for cutting-edge applications.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100573"},"PeriodicalIF":5.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental study on a new generation of recycled composite laminates","authors":"P. Bettini , L. Calervo , R. Palazzetti","doi":"10.1016/j.jcomc.2025.100571","DOIUrl":"10.1016/j.jcomc.2025.100571","url":null,"abstract":"<div><div>Composite manufacturing processes generate a significant amount of waste due to the raw material being supplied in sheet form and cut-outs. The unused scraps of prepreg are typically discarded, leading to the disposal of up to 35 % of the purchased material, accompanied by economic losses and negative environmental impacts. The authors propose collecting these scraps, cutting them into smaller, regular patches, and assembling them into a new, patched prepreg sheet. This study presents an experimental investigation into the mechanical properties of such patched material, assembled using two different architectures and three patch geometries. Five different configurations are designed, manufactured, and tested, with results compared to samples made from the original unpatched material through four-point bending tests. When patches are assembled in a regular geometry, the new material possesses around 50 % and 90 % of the original strength and stiffness, respectively, demonstrating potential for use in load-bearing applications. The methods of assembling the patches following a regular pattern also resulted in significantly better properties than a random deposition, which despite its lower cost to implement does not retain relevant mechanical characteristics. Of the two arranged investigated architectures, the one being more complex to manufacture shows 9 % and 5 % higher stiffness and strength, respectively, than the simpler one. Fracture analysis shows that failure mainly takes place in between of a patch, rather than the superposition areas.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100571"},"PeriodicalIF":5.3,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of fiber orientation on the strength of thermoplastic composite tubes subject to four-point bending","authors":"Mohammadali Rastak , Suong Van Hoa","doi":"10.1016/j.jcomc.2025.100569","DOIUrl":"10.1016/j.jcomc.2025.100569","url":null,"abstract":"<div><div>This paper presents a study on the effect of fiber orientation on the strength of thermoplastic composite tubes made by automated fiber placement. The tubes are subjected to four-point bending deformation, representing the loading conditions in helicopter landing gears. The methodology for the study consists of the development of a finite element model for two particular tubes that yields results matching those from experiments. Maximum stress criterion is used for the determination of failure. The finite element model is then used to study the stress distribution and final failure and elongation of tubes with different layers with different fiber orientations. The lay-up sequence that can provide maximum failure load is then determined.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100569"},"PeriodicalIF":5.3,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amir Ekladious , John Wang , Nabil Chowdhury , Alan Baker , Wing Kong Chiu
{"title":"Static and fatigue behaviour of hybrid step-lap joints in thick primary metallic aircraft structures","authors":"Amir Ekladious , John Wang , Nabil Chowdhury , Alan Baker , Wing Kong Chiu","doi":"10.1016/j.jcomc.2025.100567","DOIUrl":"10.1016/j.jcomc.2025.100567","url":null,"abstract":"<div><div>This study investigates the static and fatigue performance of bonded, mechanically fastened, and hybrid step-lap metallic joints in primary thick aircraft structures, focusing on both baseline configurations, representing optimally assembled joints with designed inherent strength, and those assembled with predefined bondline defects to simulate practical imperfections, that can go undetected by current non-destructive inspection techniques. The results demonstrate that hybrid joints, which integrate fasteners with adhesive bonding, significantly enhance static and fatigue failure resistance compared to traditional methods. While purely bonded joints nearly restore original stiffness, they remain prone to abrupt failure, particularly in the presence of undetectable bondline defects. In contrast, the hybrid joints tested in this study extended the fatigue life of the structure to more than nine times that of mechanically fastened joints, surpassing the aircraft’s service life by over twofold. The inclusion of fasteners effectively arrested crack propagation, preventing catastrophic failure and improving overall durability. Visual inspections, strain gauges, and optical monitoring confirmed the bolts’ role in reducing Mode I opening and peeling stresses. These findings underscore the potential of hybrid joints to enhance the durability and safety of thick aircraft structures, leading to significant cost savings by reducing the frequency of repairs and downtime.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100567"},"PeriodicalIF":5.3,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tasdeeq Sofi , Javier A. García , María R. Gude , Peter Wierach
{"title":"A novel and rapid method of integrating sensors for SHM to thermoplastic composites through induction heating","authors":"Tasdeeq Sofi , Javier A. García , María R. Gude , Peter Wierach","doi":"10.1016/j.jcomc.2025.100568","DOIUrl":"10.1016/j.jcomc.2025.100568","url":null,"abstract":"<div><div>A novel, rapid, and efficient method for bonding Piezoceramic transducers (PCTs) to high-performance thermoplastic composites using thermoplastic adhesive films (TPAFs) and induction heating is presented. The current state-of-the-art techniques to bond PCTs to composites using epoxy adhesives can take hours. This innovative out-of-oven or autoclave procedure drastically reduces bonding time to mere minutes, thereby significantly enhancing the process efficiency. Five different TPAFs were used to bond PCTs to carbon fiber polyether-ether-ketone (CF-PEEK) coupons. After determining the process window and analyzing the effects of power, coupling distance, and time on temperature, it was found that power has the greatest influence. A 20% increase in power can result in 50.9% increase in temperature as compared to time. Controlled heating and cooling ramps were developed based on the power-temperature correlation, and their effects were analyzed through differential scanning calorimetry tests. In the controlled case, the melting enthalpy of semi-crystalline TPAF increased by 4.2%, while the glass transition temperature of amorphous TPAF increased by 2.4% compared to non-controlled case. Following successful PCT bonding, mechanical performance was evaluated through static flexural and fatigue tests. TPAFs exhibited critical strains of 0.33%-0.71%, with some exceeding the critical strains of co-bonded or epoxy-bonded PCTs in previous studies by 0.13%. Microscopic analyses revealed the dominant failure mode at the composite-adhesive interface. During fatigue testing, three out of five TPAFs performed successfully, with the highest change in electro-mechanical susceptance spectra observed in amorphous TPAF equivalent to 1.87%. Overall, an efficient methodology is proposed, particularly beneficial for applications in structural health monitoring.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"17 ","pages":"Article 100568"},"PeriodicalIF":5.3,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Post-joining thermal characteristics and repair integrity of carbon fiber-reinforced thermoplastic composites during ultrasonic reconsolidation at 20 kHz","authors":"Balaji Ragupathi , Lena Burger , Frank Balle","doi":"10.1016/j.jcomc.2025.100565","DOIUrl":"10.1016/j.jcomc.2025.100565","url":null,"abstract":"<div><div>Ultrasonic reconsolidation offers significant potential to replace traditional adhesive bonding techniques used in the aerospace industries for bonding repair patches to damaged composite structures without resin additives. Temperature, a characteristic variable, is a key factor influencing the quality of joints in ultrasonic welding of thermoplastic composites. In this study, instead of measuring temperature during the joining process, the focus was on post-joining analysis on temperature at various hold times and holding forces. The findings revealed that an average hold time of 5 s and a holding force of 750 N produced higher-quality joints with minimal damages to fiber bundles and residual matrix. Additionally, it was recommended that repair patches should only undergo a maximum of two reconsolidation cycles. Beyond this point, the fibers and matrix begins to degrade, leading to a 35% reduction in mechanical performance after the fourth cycle.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100565"},"PeriodicalIF":5.3,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143101274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Monotonic and cyclic compressive performance of self-monitoring MWCNT/PA12 cellular composites manufactured by selective laser sintering","authors":"Muhammad Umar Azam , S Kumar , Andreas Schiffer","doi":"10.1016/j.jcomc.2025.100566","DOIUrl":"10.1016/j.jcomc.2025.100566","url":null,"abstract":"<div><div>Herein, we experimentally investigate the mechanical and piezoresistive properties of selectively laser-sintered cellular composites under monotonic and cyclic compressive loading. Hexagonal honeycomb structures (HHSs) with relative densities of 20 %, 30 %, and 40 % were 3D printed from a ball-milled nanocomposite powder of multi-walled carbon nanotubes (MWCNTs) and polyamide 12 (PA12) with 0.3 wt.% MWCNTs. The pure PA12 HHSs exhibited lower porosity and superior mechanical properties, including collapse strength, elastic modulus and energy absorption, particularly at higher relative densities (30 % and 40 %). Notably, the specific energy absorption for the PA12 HHSs reached 24 J g⁻¹, under out-of-plane compression at 40 % relative density. Compared to neat PA12, the MWCNT/PA12 HHSs showed a reduction in strength and modulus but demonstrated excellent energy absorption efficiency of up to 53 %. Moreover, MWCNT/PA12 HHSs exhibited exceptional strain-sensing capabilities in the elastic region with gauge factors of up to 25. Cyclic tests showed that the zero-load resistance increased significantly as damage progressed during the collapse phase, highlighting their potential for application in smart, lightweight structures with integrated strain and damage-sensing functionalities.</div></div>","PeriodicalId":34525,"journal":{"name":"Composites Part C Open Access","volume":"16 ","pages":"Article 100566"},"PeriodicalIF":5.3,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143101276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}