Composite Joints Research Articles

Effect of low velocity impact at different temperatures on hybrid adhesives in aluminium-composite single lap joints

This study aims to investigate the effect of a small stone impact on aluminum composite adhesive joints used in aircraft after exposure to various temperature conditions. In this context, single lap adhesive joints were prepared using 2024-T3 aluminium alloy sheets and 8-layer carbon fiber-reinforced epoxy hybrid composite sheets, with epoxy adhesive applied to the bonding surfaces. In addition, different types of hybrid adhesives were developed by reinforcing pure epoxy adhesive with various ratios (1%, 3% and 5% by weight) of graphene doped and undoped Nylon 6.6 (N6.6) nanofibers produced by electrospinning method to reduce brittleness. Low-velocity impact tests of 1.04 m/s under five different temperatures (−50, −20, 0, 23 and 50°C) were applied to all single lap adhesion joints produced and tensile tests were applied to the non-failed specimens to examine the loading conditions after low-speed impact. It was determined that approximately 1.5 J of the 3 J energy given by the low- velocity impact was absorbed in common in all samples, while the remaining part was returned and some separation occurred within the adhesion area due to the effect of this impact. While the low- velocity post-impact tensile strength of pure epoxy resin was measured as 2230.3 N at 23°C and 585.15 N at −50°C, the highest values were obtained in N6.6 reinforced epoxy adhesive with 1%GNP additive, which was measured as 3206.39 N at 23°C and 641.82 N at −50°C, and increased by 43.7% and 9.6% for 23°C and −50°C, respectively. In addition, the rupture surfaces of the specimens destroyed by the tensile test were examined by scanning electron microscopy (SEM) for damage analysis.

Flexural and vibration behaviours of novel covered CFRP composite joints with an MWCNT-modified adhesive

Abstract Co-curing bonding is more efficient than co-bonding and secondary bonding for structural component assembly. This work used novel covered laminas with co-cured joining techniques (CL-CCT) to create carbon fibre-reinforced polymer (CFRP) composite adhesive-bonded joints. Additionally, the researchers evaluated how multi-walled carbon nanotubes (MWCNTs) affect the bending and dynamic properties of CFRP composite joints. The researchers added various weights of MWCNTs to the covered laminas along with co-cured CFRP adhesive-bonded joints. The study revealed that epoxy and 0.25 wt% MWCNT adhesive produced the strongest and most flexible joints. These joints were 118 and 15% stronger than joints made from pure epoxy CL-CC CFRP, respectively. Compared to pure epoxy CC-CFRP composite joints, the strength of CL-CC CFRP composite joints with 0.25 wt% MWCNTs increased by 374 and 109%, respectively. Interestingly, MWCNTs with a wt% of 1.25 had the greatest natural frequency in all three vibration modes, which are 19, 19, and 13% higher than that of the pure epoxy CL-CC CFRP composite joint. There are 28, 30, and 24% more natural frequencies in 1.25 wt% MWCNT-based CL-CC CFRP composite joints than those in pure epoxy-based joints in all three modes. Analysis of variance was employed for statistical investigation. Optimization and prediction were done using an artificial neural network and the Levenberg–Marquardt technique.

Prediction of the Released Mechanical Energy of Loaded Lap Shear Joints by Acoustic Emission Measurements

In lightweight design, the usage of different optimised materials is widespread. The interfaces between two different materials are prone to damage and, therefore, the Structural Health Monitoring (SHM) of these areas is of interest. A new method for the damage evaluation of joints is developed and validated. The released mechanical energy (RME) during static loading of a metal–composite lap shear joint is considered as a damage assessment parameter and is set into relation to the detected Acoustic Emission (AE) energy. Eleven specimens with identical geometry but different surface treatments are used to form a statistical database for the method, i.e. to calculate the energy ratio and the fluctuation range, and the twelfth specimen is used for the validation of the method. The energy ratio varies significantly, but, considering the fluctuation analysis, the RME with a known range can be predicted on the basis of the AE signal. The whole process is repeated twelve times to validate the methodology. This method can be applied to different geometries and load cases without sophisticated modelling of the damage behaviour. However, load–displacement curves of the pristine joint need to be known, and the monitored joints need to be damage-tolerant and must show similar damage behaviour.

A machine learning assisted preliminary design methodology for bolted composite joints in large structures

Abstract Damage initiation hotspots around features, such as bolts and ply drops, must be investigated during the preliminary design phase of large composite structures, such as composite airframes. A global-local modelling approach is commonly employed to perform this investigation, whereby a global low-fidelity model is used to drive high-fidelity local models around the features of interest. However, this methodology is slow, repetitive and expert-dependent. In this investigation, we address these issues by applying machine learning techniques to this global-local modelling framework and demonstrate the time-saving benefit when predicting damage initiation of bolted composite joints. Feature engineering of model inputs and outputs, and appropriate customisation of machine learning methods enables damage initiation prediction. Special consideration is given to the boundary conditions that must be varied to simulate the response of the bolted composite joints. Results show over three orders of magnitude time-saving benefit and satisfactory accuracy of the proposed methodology. This indicates its potential to be developed further into a rapid design and optimisation tool.

Flexural and vibration behaviour of co-cured CFRP composite joints with MWCNT-modified adhesive

Among the diverse adhesive-bonded joining methods, the co-curing technique offers several advantages for fusing structural components. Co-curing technique effectively enhances specific strengths and ensures more equitable stress distribution. This research investigated the multi-walled carbon nanotubes (MWCNTs) incorporated with varying wt.% in carbon fibre-reinforced polymeric (CFRP) composite joints through co-cure bonding techniques. The effects of flexural and vibration behaviour in CFRP composite joints were evaluated using the three-point bending and free vibration tests. Experimental results revealed that the epoxy adhesive containing 0.5 wt.% nanofiller demonstrated the highest flexural strength and modulus. These values were significantly superior to pure epoxy adhesive, exhibiting increases of 270 and 120%, respectively. However, the 1.0 wt.% of nanofiller exhibited the maximum natural frequency under three vibration modes, which is 29, 17, and 14% higher than the pure epoxy adhesive. The statistical analysis of the results was examined using an ANOVA, ensuring the reliability of the findings. Optimisation and prediction were done with the Levenberg-Marquardt artificial neural network, further reinforcing the confidence in the outcomes. The overall coefficient (R) mean square error of 0.99844 is within the acceptable range, indicating that both outcomes are reliable and in agreement.

WrapToR composite truss joints: Concept introduction and coaxial joint analysis and demonstration

This study focuses on the development of coaxial continuously wound joint structures for Wrapped Tow Reinforced (WrapToR) trusses, which are carbon fibre composite lattice beams fabricated through a unique winding process. WrapToR truss beams have shown very high levels of performance as beam-like structures, but their usefulness can be greatly extended by using them as members within hierarchical space frames, which can be made into more geometrically complex and generally useful structures. However, the key challenge lies in creating effective joint structures able to connect together multiple WrapToR beams of different sizes and orientations. This paper addresses this challenge by presenting a modified WrapToR winding process which enables three-dimensional winding of arbitrary space frame joints, with an initial focus here on a proof of concept coaxial joint. This includes the design and manufacturing of a coaxial joint demonstrator and the development of a finite element analysis tool to predict its mechanical performance. A cantilevered beam structure combining this joint with two different sizes of WrapToR truss is built and tested, showing high levels of bending rigidity and good agreement with numerical prediction. Following this, the analysis tool is used to explore the achievable design space for coaxial WrapToR joints.

Effect of SiC particles on microstructure and mechanical properties of SiCp/AZ91 magnesium matrix composite brazed joint

The impact of SiC particles on the microstructure, mechanical properties, and fracture morphology of magnesium alloy brazed joints was investigated. The brazing experiments of AZ91+AZ91, AZ91+SiCp/AZ91, and SiCp/AZ91+SiCp/AZ91 were carried out under the same technological conditions by using the self-designed special filler metal for magnesium matrix composites. The impact of SiC particles on the microstructure and mechanical properties of brazed joints was analyzed. The addition of Ti can effectively enhance the wettability of filler metal on SiC particles. The shear strength of SiCp/AZ91+SiCp/AZ91 joints is 76.0MPa. The shear strength of the joint is 43.4% higher than that of AZ91+ AZ91.

Shear strength comparison of single lap and joggle lap adhesive joints in carbon fiber composites manufactured via vacuum-assisted resin infusion

The extensive utilization of composite materials has spurred the advancement of diverse joining techniques suitable for components constructed from such materials. This study focuses on the examination of two specific types of joints: single lap and joggle lap joints. The specimens utilized were composed of unidirectional carbon fiber composite combined with vinyl ester resin, manufactured via the vacuum-assisted resin infusion method. Vinyl ester adhesives were employed in the bonding process, with the joint surfaces undergoing sanding treatment prior to testing. Mechanical testing was conducted on the specimens according to ASTM D5868 standard, employing a constant crosshead speed until failure occurred. The test results reveal that the shear strength of single lap joints surpasses that of joggle lap joints. Within the single lap joint configuration, a mixed failure mode comprising both adhesive and cohesive failure is observed. Conversely, in joggle lap joints, substrate delamination is prevalent, suggesting the predominance of peel stress during loading.

Optimised rotational-spring component-based modelling strategy for seismic resistant steel-concrete composite joints and frames with continuous or isolated slab

Joints and frames in steel-concrete composite systems represent complex mechanical assemblies that require specific calculation procedures to optimise their detailing and structural capacity, particularly under seismic loads. To this aim, component-based modelling approaches should be able to account for the most relevant mechanisms and resistance/stiffness behaviours of individual members, and their mutual interaction. In this paper, two different simplified non-linear approaches are considered for steel-concrete composite beam-to-column joints, and are specifically applied to a seismic resistant case-study frame with X-concentric bracings. Both beam-to-column joints with or continuous (“JA” joint) or fully isolated (“JB” joint) slab are examined. First, non-linear axial springs are assembled and calibrated on the base of a previous study (“Type 1″ model (“T1″)), according to force-displacement relationships proposed in the DPC-ReLUIS Italian guidelines. Successively, a novel modelling approach based on non-linear rotational springs is presented (“Type 2″ model (“T2″)), to further simplify the computational cost of T1 strategy, and allow to efficiently account for the moment-rotation behaviour of the examined joints. The preliminary numerical validation is carried out based on past literature experiments. Moreover, the optimized T2 approach is used to explore the in-plane lateral, seismic performance of a 2D steel-concrete composite frame, which is specifically designed with X-concentric bracings. The seismic capacity of the frame (and the associated interaction of components, especially the joint zone with the bracing system) is addressed on the base of pushover analyses.

Organizational predators of disability sports participation of secondary school students with special needs in Ibadan, Nigeria

Active participation of students with disability in adapted sport is dependent on several organizational predators. The purpose of this study is to examine how organizational predators independently and jointly contribute to disability sport participation among secondary school students with special needs in Ibadan, Nigeria. The methodology featured Chain-Referral (snowball) to identify stakeholders, coaches, organizers and teachers involved in organizing disability sport for students with disability and probability sampling technique to choose the schools to be visited. The findings revealed that Strategic planning (ß=0.289, t=2.816, p=0.008), logistics (ß=0.612, t=7.103, p=0.000), interest of coaches (ß=0.536, t=7.795, p=0.000) and knowledge of organizing personnel (ß=0.500, t=7.836, p=0.000) were independently tested significant on disability sport participation while network capacity (ß=0.171, t=1.772, p=0.085), funding sources (ß=0.082, t=1.360, p=0.182) and sport infrastructure (ß=0.111, t=1.948, p=0.059) were not independently tested significant on disability sport participation. Also, there is a composite joint contribution of strategic planning, network capacity, infrastructure, funding, logistics, interest of coaches, and knowledge of organizing personnel on disability sports participation among secondary school students with special needs in Ibadan, Nigeria (F(7,39)=100.210, p=0.00). The result also generated a coefficient multiple regression of R=0.977 and R2 =0.955; implying that about 95.5% of variance was accounted for by the independent variable. Strategic planning, logistics, interest of coaches, and knowledge of organizing personnel individually and collectively showed a positive contribution to disability sport participation, hence, there is a need to consider them on the subject of disability sport participation in schools of individuals with special needs in Ibadan, Nigeria.

Experimental Investigation on the Important Factors on Structural Adhesive Joint Strength of Fiber-Reinforced Epoxy Composites

The static strength of fiber-reinforced epoxy composite structural adhesive lap joints was examined experimentally. Surface roughness and geometrical control parameters (adherent and adhesive kinds) were assessed for their effects. To examine load, elongation, and strength at failure, tensile tests were conducted. Cyanoacrylate glue outperformed SHCP 268 resin, and glass fiber-reinforced epoxy composites outperformed sisal fiber-reinforced epoxy composites. The study offers information on how to maximize adhesive bonding for lightweight multi-material design construction.

Test and simulation of high temperature resistant polyamide composite with single lap single bolt connection

The advancement of next-generation aerospace vehicles has presented new requirements and challenges for ensuring the structural integrity of aircraft components in extreme environments. Consequently, the utilization of high temperature resistant polyamide composite materials has become pivotal in the manufacturing of aerospace vehicle parts that operate under high temperatures (250 °C). As a critical connection technology for these materials, the mechanical behavior of bolted connection structures under high temperatures requires further investigation. In this paper, a combination of experimental and numerical simulation is used to investigate the load carrying capacity and failure mechanism of T700/BMP316 composite bolted joints at room temperature and 250 °C. The experimental results show that the ultimate load carrying capacity of the structure at 250 °C is only 13.1 % lower than that of the room temperature environment, indicating that the temperature softening effect of such composites is not significant. Scanning electron microscope (SEM) and computed tomography (CT) results indicate that the structural damage modes were the crushing of the hole edge fibers and matrix due to the extrusion by the bolts, as well as the interlaminar delamination damage. Temperature effects were taken into account for the composite principal structure and finite element modeling was performed using a combination of Pinho criterion and Cohesive model. Numerical simulations allow accurate prediction of the load-displacement response and damage pattern throughout the damage evolution phase. The high temperature test results and the developed finite element model involved in this study can support the design of new-generation aerospace vehicles.

Experimental and numerical investigation on composite beam–column joint connection behavior using different types of connection schemes

Abstract Over the past few decades, composite joints have been regarded as one of the most promising approaches. After reviewing the research articles dealing with composite beam-column joints, it can be withdrawn that few researchers studied and developed different types of composite beam-column joints. The objectives of this paper to study the effect and behavior of different connection types on the composite beam – column joint under repeated loading as well as to investigate new forms of slab connection with column flange in composite connection joints, aiming to enhance the behaviors of the joints and make the slab endure a part of the load in a more efficient way. Five specimens with various connection types were tested to failure; the composite model number two (CM2) was considered the control specimen. Regarding the ultimate moment, the result found that CM5 has moment 50.47% more than control specimen, the lowest rotation value was in CM5. The general behaviours of the FEM were in good accordance with the experiment results. According to the parametric a higher yield strength is more rigid stiffer, the effect of web thickness on the load is too small and increase in load resistance with an increase in beam flange thickness.

Numerical prediction on the fatigue debonding behaviour in a complex bi-material interface: A case study on wrapped composite joints

Debonding is one of the most critical failure modes for bonded joints under fatigue loads. Numerical prediction on the fatigue debonding behaviour of bonded interfaces with complex geometry still remains a problem. This paper proposes a numerical methodology based on fracture mechanics to predict crack growth in a complex bi-material interface and illustrates the prediction procedure by a case study on wrapped composite joints. Interface coupon tests provide the fatigue crack growth properties at the composite-to-steel interface used as inputs for finite element (FE) modelling. The FE model is calibrated against fatigue tests of small scale wrapped composite joints with different steel surface roughness subject to different load levels. A sensitivity analysis is conducted to investigate the influence of key modelling parameters. The calibrated model is validated against fatigue tests on upscaled joints. Good agreements are shown between the test and modelling results in terms of crack growth and stiffness degradation, demonstrating the potential of the proposed numerical methodology for predicting fatigue debonding behaviour of complex bi-material interfaces.

Effects of ZrO2 Nano-Particles' Incorporation into SnAgCu Solder Alloys: An Experimental and Theoretical Study.

This study investigates the mechanism and effects of incorporating different ZrO2 nano-particles into SAC0307 solder alloys. ZrO2 nano-powder and nano-fibers in 0.25-0.5 wt% were added to the SAC0307 alloy to prepare composite solder joints by surface mount technology. The solder joints were shear tested before and after a 4000 h long 85 °C/85% RH corrosive reliability test. The incorporation of ZrO2 nano-particles enhanced the initial shear force of the solder joint, but they decreased the corrosion resistance in the case of 0.5 wt%. SEM, EDS, and FIB analysis revealed intensive growth of SnO2 on the solder joint surfaces, leading to the formation of Sn whiskers. Density functional theory (DFT) simulations showed that, despite Sn being able to bond to the surface of ZrO2, the binding energy was weak, and the whole system was therefore unstable. It was also found that ZrO2 nano-particles refined the microstructure of the solder joints. Decreased β-Sn grain size and more dispersed intermetallic compounds were observed. The microstructural refinement caused mechanical improvement of the ZrO2 composite solder joints by dispersion strengthening but could also decrease their corrosion resistance. While ZrO2 nano-particles improved the solder joint mechanical properties, their use is recommended only in non-corrosive environments, such as microelectronics for space applications.

An intelligent CFRP bolt with embedded carbon nanotube eddy current sensors for damage self‐diagnosis of bolted composite joints

AbstractRecognizing the critical demand for composite bolts and the damage‐mode complexity of composite bolt joints, this study introduces the concept of an intelligent carbon fiber reinforced polymer (CFRP) bolt, which achieves self‐monitoring of damage in small and complex CFRP bolted joints. The proposed eddy current sensor (ECS) is mainly composed of a coil made of carbon nanotube film and encapsulated with epoxy resin film. This achieves homogeneous embedding of the sensor by using the same material for both sensor and bolt. The CFRP bolt is fabricated by molding process, with the proposed ECS embedded in bolt shank. The numerical simulation results indicate that hole‐edge damages impact the distribution of induced current density and eddy current flow in CFRP plates. Additionally, the impedance amplitude of the ECS effectively monitors bearing damage propagation. Shear tests confirm that the integration method of the proposed ECS within the CFRP bolt introduces negligible intrusion to the host bolt's integrity. Experimental results demonstrate that the intelligent CFRP bolt can effectively monitor the damage propagation at the hole edge, with an accuracy for bearing damage exceeding 0.5 mm. At a working frequency of 10 MHz, the sensor's sensitivity in detecting a 0.5 mm bearing damage reaches 4.20%.Highlights An intelligent CFRP bolt was fabricated using the molding method. The embedding of the ECS did not cause adverse effects on the bolt. The proposed EC sensor is composed of carbon nanotube and epoxy resin adhesive films. The eddy current distribution at the hole edge of the CFRP bolted joints is analyzed. The ability of intelligent bolts to monitor hole edge damage is verified by experiments.

АНАЛІЗ РОЗПОДІЛУ КОНТАКТНИХ НАПРУЖЕНЬ У ДВОЗРІЗНОМУ БОЛТОВОМУ З'ЄДНАННІ КОМПОЗИТНИХ ТА МЕТАЛЕВИХ ЕЛЕМЕНТІВ

Bolted joining technique is the dominant joining method for CFRP load-carrying structures in aircraft. However, the weak point of such structures are the areas located in the vicinity of the fastener holes, which are the areas of increased stress concentration. In addition, drilling the holes results in structural discontinuities due to cutting material fibers. Among all failure modes of composite bolted joint, bearing failure is one of the most common type of damage. This failure is caused by the local compressive stresses acting normal to the contact surface, that leads to delamination of material due to insufficient strength of matrix. Therefore, it is extremely important to optimize the design of composite bolted joints in order to enhance the entire composite structure. To increase the load-carrying capacity of the composite joint structural parts and protect the hole walls from damage, a method for installing titanium bushing with glue into the holes of composite plate is proposed. The paper presents the results of numerical analysis of the impact of stacking sequence on the distribution of contact stresses in a double-shear bolted joint of composite plate to steel cover plates. Using the finite element method and ANSYS Workbench 2019 R3 software, a three-dimensional finite element model of a double-shear bolted joint was created, which enables to analyze the impact of the stacking sequence on the distribution of contact stresses at the bolts to titanium bushings interface in the case of uniaxial tension of the middle composite plate at the level of tensile stresses in the gross section of 100 MPa. The obtained result explains the fundamental difference in the behavior of composite and metal materials: due to the change in the orientation and sequence stacking, the stiffness of the composite element of the joint changes, which affects the ovalization of the holes and the level of local deformations of the bushings, which in turn leads to a change in the maximum contact stresses and their concentration. By optimizing stacking sequence, it was possible to reduce the level of maximum contact stresses by 1.1 times. At the same time, the degree of unevenness of the distribution of contact stresses decreased by 1.21 times. The optimal stacking sequence was one in which 37.5% of the fibers oriented at an angle of 0°, 50% of the fibers oriented at angles of ±45°, and 12.5% of the fibers oriented at an angle of 90°

Enhanced shear and vibration behaviour of co-cured CFRP joints with innovative lamination techniques

ABSTRACT The adhesive bonding technique is extensively employed in large-scale component manufacturing to efficiently join the fibre-reinforced composite laminates. The following adhesive bonding techniques, such as secondary bonding, co-bonding and co-curing techniques, were modified by novel interleaved and covered lamination techniques. The shear and vibration behaviour of carbon fibre reinforced polymeric (CFRP) composite single lap joint were investigated per ASTM D5868 standards with innovative lamination techniques. The findings demonstrated that the Co-Curing with the Covered Lamination Technique (CL-CCT) showed an excellent shear strength of 88% higher than the secondary bonding technique. The Co-Curing with Interleaved Lamination Technique (IL-CCT) demonstrated a significant enhancement in shear strength, surpassing the secondary bonding technique by 74%. Furthermore, the Co-Bonding with the Covered Lamination Technique (CL-CBT) exhibited a 44% increase in natural frequency. The Co-Curing with Covered Lamination Technique (CL-CCT) also outperformed the conventional secondary bonding technique, demonstrating a remarkable 32% improvement in natural frequency. Eventually, the adhesive and cohesive failure modes are observed in the overlap zone of CFRP composite single-lap joints.

Physics-Informed Neural ODE with Heterogeneous control Inputs (PINOHI) for quality prediction of composite adhesive joints

Composite materials have long been used in various industries due to their superior properties such as high strength, light weight and corrosive resistance. Bonded composite joints are finding increasing applications, as they provide extensive structural benefits and design flexibility. On the other hand, the failure mechanism of composite adhesive joints is not fully understood. A model that bridges manufacturing parameters and final quality measures is highly desired for the design and optimization of the manufacturing process of composite adhesive joints. In this study, a novel framework of Physics-Informed Neural Ordinary Differential Equation (ODE) with Heterogeneous Control Input (PINOHI) is proposed, which links the heterogeneous manufacturing parameters to the final bonding quality of composite joints. The proposed model structure is heavily motivated by engineering knowledge, incorporating a calibrated mathematical physics model into the Neural ODE framework, which can significantly reduce the number of data samples required from costly experiments while maintaining high prediction accuracy. The proposed PINOHI model is implemented in the quality prediction of composite adhesive joints bonding problem. A set of experiments and associated data analytics are conducted to demonstrate the superior property of the PINOHI model by using both the leave-one-batch-out cross-validation and sensitivity analysis.

A novel method for strengthening C/C composite joint with high entropy alloy/Ni composite interlayers by spark plasma sintering: In-situ synthesis of high entropy cermet joint structure

C/C composite was successfully brazed with TiZrHfTa/Ni or ZrHfNbTa/Ni composite interlayers using spark plasma sintering. The influence of different interlayers and joining parameters on the joint morphology, shear strength at room temperature and 1000 °C was investigated. For both composite interlayers, the C/C joints obtained at 1800 °C for 30 min consisted of a single high entropy cermet structure, with a near equimolar high entropy carbide hard phase and a near pure Ni binder phase. However, the use of different composite interlayers resulted in differences in the elastic modulus and hardness of the formed high entropy carbide phase. The maximum shear strengths of the obtained C/C composite joints using TiZrHfTa/Ni and ZrHfNbTa/Ni interlayers at room temperature were close, with value of 37.49 ± 1.44 MPa and 38.95 ± 1.26 MPa, respectively. Because (Zr-Hf-Nb-Ta)C had better high-temperature stability than (Ti-Zr-Hf-Ta)C, the obtained C/C-ZrHfNbTa/Ni-C/C joint exhibited a higher shear strength of 28.54 ± 1.71 MPa at 1000 °C. After shear testing at both room temperature and 1000 °C, fractures in all joints predominantly occurred within the C/C composite near the reaction layer, indicating a substrate failure mode. The use of composite interlayers resulted in C/C composite joints with excellent shear strength, primarily due to the in-situ synthesized high entropy cermet reaction layer, which provided superior strength and toughness. Additionally, the laser-textured pattern on the C/C composite surface formed numerous interlocking structures at the joint interface, further enhancing the joints' shear strength.