Table of Content

25 December 2025, Volume 53 Issue 12

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Intelligent Transportation System

A Method for Joint Optimization of Signal Timing and Vehicle Trajectories at Intersections Based on Hierarchical Soft Actor-Critic Reinforcement Learning

MA Yingying, LI Teng, LIANG Yunyi, TANG Meng

2025, 53(12):  1-16.  doi:10.12141/j.issn.1000-565X.240549

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This study proposes a joint optimization method for intersection signal timing and vehicle trajectory based on the Soft Actor-Critic (SAC) reinforcement learning framework. The model consists of two layers: signal ti-ming optimization and vehicle trajectory optimization. The state space for both layers includes vehicle position, speed, and traffic signal status, while the reward function is a weighted sum of traffic efficiency, safety, and fuel consumption. In the signal timing optimization layer, the action is the duration of the signal phase, and in the vehicle trajectory optimization layer, the action is the vehicle acceleration. Each optimization layer has independent value networks and policy networks. The value network outputs the state-action value and assesses the policy network’s performance according to the current state and action. The policy network generates the mean and standard deviation of a Gaussian distribution based on the current state and samples actions from this parameterized Gaussian distribution. The loss function of the policy network includes entropy and temperature coefficients to automatically adjust the breadth and depth of policy exploration, reducing the model’s sensitivity to hyperparameter variations. To address the inconsistency in the intervals between signal timing optimization and vehicle trajectory optimization, this study designed an asynchronous training algorithm for the signal timing layer and vehicle trajectory optimization layer. Both the value network and the policy network of the same layer were trained simultaneously using backpropagation. The model was trained and evaluated with SUMO, and experimental results indicate that the proposed method reduces vehicle fuel consumption by an average of 24.24%, 5.39%, and 22.23%, compared to mathematical programming methods, signal-timing-only optimization methods, and trajectory-only optimization methods, respectively. It can achieve energy optimization without significantly reducing average speed, while maintaining performance deviations within 5% under state observation disturbances, demonstrating good robustness.

Modeling Methodologies for Unmanned Aerial Vehicle Path Planning in Emergency Rescue: A Comprehensive Review and Prospect

PEI Mingyang, SHAO Kangshun, LI Linqing, XU Fengjuan

2025, 53(12):  17-33.  doi:10.12141/j.issn.1000-565X.250037

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With the rise of the low-altitude economy, the application scenarios of unmanned aerial vehicle (UAV) continue to expand, particularly playing a significant role in emergency response. Leveraging advantages such as high mobility and remote control, UAV has proven to be powerful tools in disaster monitoring, communication restoration, personnel search and rescue, material delivery, and post-disaster assessment during emergencies such as natural and human-made disasters. This paper aims to provoide a comprehensive review of modeling methods and the latest research progress in UAV path planning for emergency rescue, offering thorough theoretical references and technical guidance for researchers in related fields. It begins by outlining typical emergency rescue scenarios such as earthquakes, fires, and floods, summarizing the application requirements of UAV in different contexts. Then it systematically reviews UAV path planning modeling methods, including dynamic models and task models, with task models further categorized into hierarchical, collaborative, fault-tolerant, real-time, and adaptative dimensions. Subsequently, it comprehensively analyzes path planning optimization algorithms based on three core elements: constraints, optimization objectives, and solution algorithms. Finally, the paper discusses the challenges and opportunities of UAV path planning in emergency rescue, highlighting that technological development, multi-UAV collaboration, and interdisciplinary integration represent future development opportunities. This study provides theoretical support and practical reference for the further development and application of UAV path planning modeling.

Speed Secondary Guidance Strategy for Signalized Intersection Considering Driver Acceptance Level

CHENG Guozhu, SHI Zeyu

2025, 53(12):  34-45.  doi:10.12141/j.issn.1000-565X.240503

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This study proposes a secondary speed guidance strategy that incorporates driver acceptance levels to enhance the traffic efficiency address and reduce fuel consumption and emissions in the upstream areas of signalized intersections. The strategy addresses the inadequate execution of guidance strategies by drivers in manual driving environments. Focusing on connected human-driven vehicles, it introduces the parameter of driver acceptance degree to refine three primary guidance models: acceleration guidance through, deceleration guidance through, and deceleration guidance to stop. To mitigate the impact of low driver acceptance, secondary acceleration guidance through and secondary deceleration guidance through models are constructed. Using the Matlab simulation platform, this study established a simulation environment that considers vehicle trajectory, speed, acceleration, fuel consumption, and emissions. Comparative analyses of no guidance, primary guidance under varying driver acceptance levels, and secondary guidance were conducted. The simulation results show that strictly following the primary guidance strategy can enable more vehicles to pass through the intersection without stopping, improving traffic efficiency by approximately 14.3%, and reducing fuel consumption and emissions by 10% to 15%. Low driver acceptance has a significant negative impact on primary speed guidance, rendering the primary guidance strategy ineffective and causing additional fuel consumption and emissions. The secondary guidance strategy can effectively alleviate the impact of low driver acceptance, restoring traffic efficiency to over 95% of that of primary guidance and reducing fuel consumption and emissions by approximately 8% to 12%.

Signal Control Method of Adaptive Traffic Events in Connected Traffic Environment

JIANG Xiancai, WU Zhanling, SAN Jingqi

2025, 53(12):  46-60.  doi:10.12141/j.issn.1000-565X.240533

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The existing signal control methods for traffic incidents often fail to account for the impact of traffic flow redistribution caused by current intersection control scheme adjustments on adjacent intersections. This oversight essentially shifts traffic problems to adjacent intersections rather than resolving congestion effectively. In view of this, this study proposes an adaptive traffic incident signal control method (SCM-ATE) by leveraging the testability of networked traffic, the controllability of connected autonomous vehicles (CAVs), and the inducibility of connected human-driven vehicles. The SCM-ATE method uses the shortest path algorithm to plan the diversion path of obstructed traffic flow based on the determination of lanes and traffic flow caused by events, as well as the sufficient traffic capacity of adjacent intersections. The optimization objective is to minimize the average delay of vehicles at all intersections on the diversion path. A dynamic programming approach is then applied to jointly optimize signal timings and trajectories of connected vehicles along the designated route, thereby mitigating the adverse effects of incidents. The simulation results show that under low, medium, and high traffic loads, compared with traditional signal control methods, the SCM-ATE method reduces the average delay of vehicles by 12.56%, 20.34%, and 5.29%, respectively. Compared with the single-layer method using single intersection traffic signals and collaborative vehicle trajectory joint optimization (JOTS-CVT), the average delay of vehicles is reduced by 13.27%, 10.40%, and 1.25%, respectively. These outcomes confirm the effectiveness of SCM-ATE in enhancing traffic efficiency. Further research shows that the intersection traffic load and the penetration rate of networked autonomous vehicle have a significant impact on the optimization effect of SCM-ATE and the SCM-ATE method is more suitable for traffic scenarios where the penetration rate of networked autonomous vehicle is ≥ 0.3 and the lane flow rate ratio at the intersection is ≤ 0.7.

Optimization of Cross-Line Train Operation Scheme for Passenger Flow Corridors in Urban Rail Transit

XU Qi, PANG Liyan, XUE Likai, LI Jiehui, HE Peng

2025, 53(12):  61-70.  doi:10.12141/j.issn.1000-565X.250107

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Urban rail transit passenger flow corridor connect core urban areas with key functional zones across different urban spatial layers, representing concentrated areas of urban spatial resources and economic activities. Their transportation efficiency significantly impacts both the capacity of the rail transit network and socio-economic activities. Focusing on these corridors, this study adopts a “trunk line with multiple branches” topological structure to develop a multi-objective nonlinear optimization model that minimizes enterprise operational costs, passenger travel costs, and load factor imbalance. The model uses train frequency and marshaling plans as decision variables as decision variables, solved via an NSGA-Ⅱ algorithm. Using Beijing’s Huilongguan/Tiantongyuan-Zhongguancun corridor as a case study, the model demonstrates effective accommodation of multi-directional travel demand between residential and employment hubs. To evaluate optimization performance, an improved distance-based optimal solution selection method identifies a solution with 2 639.17 h (passenger travel time), 103 716.24 yuan (operational cost), and 0.086 (load factor imbalance). Compared to isolated line operation schemes, this achieves 14.09% reduction in passenger travel time and 43.01% lower load factor imbalance, with a 17.22% increase in operational costs. At the same time, in complex line networks, the restrictions of the maximum carrying capacity of the main line section and the minimum service level of the branch section have a great impact on the effect of the optimization scheme. By increasing the upper limit of the main line capacity, the study investigates the impact of capacity restrictions on the optimization of train operation schemes in passenger flow corridors. The results show that under the condition of improving the line carrying capacity, the diversity of Pareto solutions increases, passenger travel time is significantly reduced, and the balance of service is improved. These findings provide empirical guidance for cross-line operation planning and practical rail transit management.

Structural Safety

Analysis of Mechanical Performance of Precast Concrete Floor Slabs Containing Recycled Components

LI Yan, WU Bo, ZHENG Shuya, WU Xiang

2025, 53(12):  71-81.  doi:10.12141/j.issn.1000-565X.250287

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The direct utilization of recycled components derived from meticulously demolished old concrete members in new structural elements holds significant potential for saving materials, reducing energy consumption, and lowering carbon emissions. However, the performance of such new members requires systematic investigation for quantitative understanding. As a preliminary exploration, this paper investigated the flexural performance of precast concrete floor slabs containing recycled components. Flexural experiments were conducted under both sagging and hogging moments. The influences of factors such as the surface treatment methods of recycled components and the strength difference between new and old concrete on the sagging moment flexural performance was examined. Furthermore, the effect of the configuration of locally added connecting reinforcement on the hogging moment fle-xural performance was studied. A calculation methods for the flexural capacity of these slabs was proposed. The results show that: (1) the sagging moment flexural capacity of the recycled-component slabs is significantly higher than that of monolithic cast reference slabs; (2) Different surface treatment methods for the recycled components generally had a limited impact on the sagging moment capacity; (3) the addition of local connecting reinforcement at the ends of the recycled components notably enhanced the hogging moment flexural capacity; for practical enginee-ring, the configuration using directly laid lapped reinforcement is recommended. The results of the proposed me-thods for calculating flexural bearing capacities are generally conservative.

Analysis of Shear Force Transfer Mechanism of Reinforced Concrete Beams Without Stirrups

FU Chongyang, XIONG Ergang, LI Sifeng, LIU Fengwei, YU Jiatong

2025, 53(12):  82-93.  doi:10.12141/j.issn.1000-565X.250066

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To investigate the variation in shear force transfer mechanisms of reinforced concrete (RC) beams without stirrups, 9 rectangular-section and 27 T-section RC beams without stirrups were designed, fabricated, and tested. Displacements and strain data were collected using digital image correlation (DIC), displacement transdu-cers, and strain gauges. Kinematic images of critical shear cracks were plotted, and the contributions of four shear transfer mechanisms—aggregate interlock, dowel action, residual tensile stress across cracks, and shear resistance of the uncracked compression zone—were quantified throughout the loading process. The evolution of these mechanisms during loading was analyzed. The results indicate that the number, development, and height of shear cracks exhibit a complex coupling effect on the four shear force transfer mechanisms; aggregate interlock generally reaches its maximum contribution at approximately 0.9 P_u (where P_u is the peak load), and its calculated shear resistance varies little with the shear-span ratio; however, its proportional contribution decreases as the shear-span ratio decreases; dowel action remains relatively stable throughout loading, yet its relative contribution diminishes as the overall shear capacity increases. Residual tensile stresses across cracks contribute primarily in the early loading stage and diminish to zero at peak load due to full crack development. The shear capacity provided by the uncracked compression zone is influenced by multiple factors, most notably the shear-span ratio—the shear capacity in beams with small shear-span ratios can be more than twice that in beams with large shear-span ratios. At peak load, aggregate interlock is the dominant shear force transfer mechanism in beams with larger shear-span ratios. However, as the shear-span ratio decreases, the contribution of the uncompressed concrete zone increases rapidly and becomes the predominant mechanism.

Lateral Resistance of Multi-Storey Steel Frame with Sparse Chevron Bracings

HE Liang, XU Zhaoyu, SHEN Wenjie, TONG Genshu, LIU Zhixin, ZHANG Lei

2025, 53(12):  94-106.  doi:10.12141/j.issn.1000-565X.240596

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This study conducts an in-depth investigation into the lateral resistance of multi-storey steel frames with sparse chevron bracing. By combining finite element analysis and theoretical derivation, the mechanical behaviour of structures with under-strengthened beams and its influence on lateral resistance are systematically examined. Through elastoplastic pushover analysis, the accuracy of the series-parallel theoretical model for dual lateral force-resisting systems is validated, and the variation of bracing internal forces with inter-story drift angle is revealed. Finite element results indicate that the stiffness and strength of beams significantly influence the development of tensile brace forces after buckling of the compressive brace. As a secondary lateral force-resisting system, the frame effectively compensates for the degradation in load-bearing capacity after brace buckling. In addition, the composite effect of the slab effective width and steel beam notably enhances the flexural stiffness of beam, thereby facilitating the development of tensile brace forces, and reducing the degradation of load-bearing capacity after compressive brace buckling. For rigid frame-chevron bracing structures with inadequately strengthened beams, under the combined action of lateral displacement and unbalanced forces, plastic hinges in the beam initially form at the beam end on the compressive brace side, followed by the mid-span of the beam. Based on this failure mode, formulas for calculating tensile brace forces and beam unbalanced forces are derived, demonstrating high accuracy. The study indicates that even when beams do not meet the sufficient strengthening requirements specified in Clause 8.2.6-2 of the Code for Seismic Design of Buildings, the overall load-bearing capacity does not deteriorate with increasing lateral displacement, provided that the frame contributes a relatively high proportion of lateral resistance. This ensures structural safety under seismic actions with an intensity of 7 degrees (0.1g). The proposed calculation method for beam unbalanced forces provides a new approach to optimizing chevron-braced frame design, avoiding the problem of excessively large beam depths in traditional design, and offering important theoretical support and practical guidance for engineering applications.

A Multi-Parameter Discrimination Method for Failure Modes of RC Beam-Column Joints Based on Fisher Transform and Bayes Classification Principle

WANG Suguo, FAN Cunxi, ZHENG Yi

2025, 53(12):  107-116.  doi:10.12141/j.issn.1000-565X.250203

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The various failure modes of reinforced concrete (RC) beam-column joints under lateral loading exert different impacts on the structural performance. Thus, accurately categorizing component failure modes is pivotal for determining the deformation performance limits in structural performance design. Existing research lacks clear boundaries between different failure modes of beam-column joints, and it remains difficult to distinguish intervals corresponding to distinct failure types using a single parameter. This paper proposes a more accurate and practical discriminant method for identifying failure modes in interior beam-column joints, incorporating multiple parameters based on the Fisher transform and Bayes classification principles. The method initially employs the Fisher discriminant analysis to identify projection spaces with maximum separation between classes, projecting original samples into these optimally separated spaces to obtain new samples more amenable to classification. Subsequently, Bayes classification principles are applied for discriminant analysis of the new samples. In studying interior joint failure mode classification, based on this method the corresponding multi-parameter classification discriminant equations are established using a combination of four parameters: axial compression ratio, shear compression ratio, concrete strength, and stirrup characteristic value. This approach effectively classifies failure modes of interior beam-column joints and clearly defines intervals corresponding to different failure types. Furthermore, through sensitivity analysis of influencing factors, the study determines that the shear compression ratio has the most significant influence on failure modes, followed by the stirrup characteristic value. Therefore, adjusting the shear compression ratio and the stirrup characteristic value is an effective means of preventing shear failure at this type of joint.

Model Test Study on Steel-Concrete Joint Segment of Arch Foot of A Long-Span Flat Arch Bridge

LIU Wenshuo, LI Ang, WANG Hailong, LUO Qiong, LI Jianquan

2025, 53(12):  117-125.  doi:10.12141/j.issn.1000-565X.250078

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To investigate the stress behavior and load-transfer mechanism at the steel-concrete joint segment of a flat arch bridge, this study takes a flat arch bridge in Guangdong with a calculated span of 196 m as the engineering background. Based on the Abaqus platform, a refined finite element model of the steel-concrete composite arch abutment was established to analyze the stress level and distribution characteristics of the structure under six unfavorable load cases. In addition, a 1∶8 scaled patial model was fabricated for multi-condition loading tests to study the mechanical behavior of the steel-concrete joint segment under different scenarios. The results indicate that, under all loading cases, the stress in the bottom plate of the steel arch box is most significant, making it the primary load-bearing component, with a maximum stress of -116.875 MPa. In the stress distribution of the bottom plate, the stiffening ribs play a major role, exhibiting the most prominent stress levels compared to other areas. The web area adjacent to the bottom plate of the steel arch box experience the next highest stresses, with a maximum value of -32.16 MPa across all conditions. The stress level in the top plate of the steel arch box is relatively low. The measured stress values in the concrete pile cap are generally small, with a maximum stress not exceeding -0.73 MPa. The axial compressive stress in the steel arch box gradually decreases from the loading end to the concrete pile cap end. When subjected to loads, the steel arch box primarily transfers the applied loads to the concrete pile cap through the bottom plate and the adjacent web regions. Under all test conditions, the stress level at the steel-concrete joint segment is relatively low, as most of the stress from the bottom plate of the steel arch box is dispersed into the concrete pile cap via components such as PBL shear connectors, bearing plates, densely arranged stiffening ribs, and penetrating reinforcement bars.

Monitoring and Simulation Analysis of Prestressing Effect During Construction of Wet Joints of Simply-Supported-to-Continuous T-Beam Bridge

SHEN Lei, YU Zhiping, HUANG Fangyuan, XU Chen, WAN Peng

2025, 53(12):  126-139.  doi:10.12141/j.issn.1000-565X.250068

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This study investigates the effect of prestress tensioning in the negative moment region on the mechanical behavior of flange plate wet joints, using an under-construction simply-supported-to-continuous T-beam bridge as a case study. Through construction process monitoring and parametric numerical simulations, the stress distribution patterns in the wet joints were analyzed. For construction convenience, the referenced project adopted the sequence of tensioning prestressing tendons first, followed by casting longitudinal wet joints. The parametric analysis considered two additional scenarios beyond the original construction sequence (Method 1): casting wet joints before tensioning prestress (Method 2), and partially casting wet joints in the negative moment region before tensioning prestress, followed by casting the remaining wet joints (Method 3). Monitoring results showed that while the actual prestress tensioning levels varied by over 10% during construction, the wet joints remained largely unaffected due to post-tension casting. After completion of wet joint casting, transverse stresses were predominantly compressive, with longitudinal tensile stresses only observed near transverse beams at low levels (maximum value: 15 × 10^-6). Monitoring data indicated that prestress tensioning did not directly increase the cracking risk of wet joints. Parametric analysis demonstrated that all three construction methods provided certain stress margins for wet joints, with maximum principal tensile stresses under permanent loads measuring 0.3, 1.5 and 0.9 MPa respectively. The first two methods showed continuous significant tensile stress development after superimposed dead load application, while the third method (staged casting of wet joints) maintained low tensile stresses even after superimposed dead load, though it involved more complex construction procedures. These findings provide valuable references for mechanical analysis and process optimization in similar structural construction projects.

Materials Science & Technology

Influence Mechanism of Coarse Aggregate Morphology on Meso-Mechanical Behavior of Asphalt Mixtures

HE Jun, YU Jiangmiao, LI Weixiong, CHEN Bo, SHI Liwan, ZHANG Xiaoning

2025, 53(12):  140-152.  doi:10.12141/j.issn.1000-565X.250121

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To reveal the influence mechanism of coarse aggregate profile characteristics on the meso-mechanical properties of asphalt mixtures, this study employed digital image processing technology to obtain the profile characteristics of coarse aggregates and constructed discrete element models of coarse aggregates with multiple morphological features. Combined with a virtual uniaxial penetration test system, the impact of aggregate geometry on the meso-mechanical response of asphalt mixtures was investigated. The results indicate that a mixed tensile-compressive stress mode exists at aggregate contact points, with compressive stress accounting for 40%~50%, tensile stress for 10%~20%, and mixed stresses for 30%~40% of the total. The application of uniaxial penetration load leads to rapid growth in microcrack numbers. In mixtures with higher elongated and flat aggregate content, microcracks at the aggregate-asphalt interface connect more readily to form through cracks, whereas mixtures with higher cubical aggregate content exhibit smaller microcrack distribution areas and lower stress levels. Microcracks are mainly induced by shear stress, accounting for about 90% of total microcracks; the number of microcracks caused by tensile stress is relatively small, accounting for about 10%. The maximum microcrack length reaches 10 mm, while the minimum is approximately 0.2 mm. For mixtures rich in cubical coarse aggregates, skeleton interlocking effectively resists loading. These findings provide theoretical support for coarse aggregate selection in asphalt pavement construction and quality improvement in aggregate processing.

Computational Model for Chloride Diffusion Coefficient in Concrete Considering the Influence of Cement Type and Strength

ZHU En, YANG Lufeng

2025, 53(12):  153-160.  doi:10.12141/j.issn.1000-565X.240573

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To address the limitations of traditional models in cross-laboratory validation, this study proposes a chloride diffusion coefficient model for concrete that incorporates a cement type factor, accounting for the influence of cement type and strength grade. The model is developed through regression analysis of multi-source large-sample Rapid Chloride Migration (RCM) test data. Firstly, a comprehensive database of 179 RCM test datasets from 70 laboratories was established to analyze the effects of water-binder ratio, cement type, and strength grade on the chloride diffusion coefficient via regression. Furthermore, the cement type factor was introduced into the computational model using a two-phase regression method, and its value was determined based on the multi-source large-sample data. Finally, comparative analyses with traditional models and validation using independent test data were conducted. The results show that the proposed multi-source large-sample model improves the fitting accuracy to experimental data by 19.6% compared to conventional mono-source small-sample models. The cement type factor effectively captures the combined influence of cement type and strength, reducing the weighted average error and coefficient of variation by 32.0% and 25.0%, respectively, thereby significantly enhancing the model’s predictive precision and adaptability.

Microscopic Mechanical Analysis of Interface Deformation During Pull-Out of Single Polypropylene Fiber

BI Yujie, MAO Lingtao, LIU Haizhou, LIU Jiaojiao, LIU Yifan

2025, 53(12):  161-171.  doi:10.12141/j.issn.1000-565X.240560

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To investigate the bonding mechanical properties between polypropylene fiber and concrete interface, this study analyzed the debonding process of the interface through single fiber pull-out microscopic mechanical experiments and numerical simulations. An in-situ scanning observation system was established using micro CT and a self-developed single fiber drawing device to observe the process of pulling out a single polypropylene fiber with indentation from the mortar matrix. The deformation fields of the interface between fiber and matrix was obtained with mechanically regularized global digital volume correlation, and the interface debonding was quantified by calcula-ting the relative displacement of the shared nodes between the fiber and the matrix. A 3D microscopic numerical model reflecting the true shape of fibers and matrix was established based on CT images, and the single fiber dra-wing process was simulated and analyzed. The results show that the force-displacement curves display multi-peak fluctuations corresponding to the fiber geometry after the peak. The strain fields at interfaces measured by digital volume correlation and numerical simulation show a strain concentration phenomenon related to the geometric shape of the indentation fiber, indicating that the periodic indentation of the fiber increases mechanical interlocking and friction forces between the fiber and the matrix during pullout. The relative displacement at the interface is greatest and decreases along the fiber’s axial direction. In the horizontal direction, the variation of relative displacement was correlated with the geometric shape of the fiber. The relative displacement in the vertical direction reflected that the fiber and matrix have completely debonded before the pullout force reaches the peak load.

Rapid Prediction of Thermal Properties of Automotive Basalt Fiber Composites Based on Fitting Regression Function

WANG Tong, MA Yupeng, ZHAO Yang

2025, 53(12):  172-182.  doi:10.12141/j.issn.1000-565X.250122

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The traditional process of new material development, heavily reliant on extensive experimentation and empirical knowledge, suffers from low efficiency, prolonged cycles, and high costs. Integrating efficient experimental techniques with rapid computational simulation and prediction through intelligent methods can significantly shorten the R&D and engineering application cycle while reducing costs. Chopped basalt fiber-reinforced polylactic acid (BF/PLA) composites, being naturally green, environmentally friendly, and biodegradable, represent an ideal alternative material for automotive interior and exterior components with considerable development potential. In order to study the influence of different fiber parameter ratios on the thermal properties of BF/PLA composites and facilitate rapid development of suitable automotive component materials, this study first conducted experiments on the thermal properties of BF/PLA composites under various fiber parameter ratios. Through data correlation analysis, the effects of different fiber parameter ratios on composite thermal properties were examined. Using F-values from three-factor ANOVA, a fiber parameter quasi-centralization method was proposed, establishing fitted regression functions between glass transition temperature/crystallinity and centralized variables. Based on these regression functions and polynomial guiding functions, new ratios of fiber mass fraction, diameter, and length parameters were incorporated to obtain centralized variables for glass transition temperature and crystallinity under the new parameter ratios. The glass transition temperature and crystallinity of BF/PLA composites with new parameter ratios can be obtained by fitting regression function, and the thermal properties of composites with more fiber para-meter ratios can be predicted by fitting regression function, and the determination coefficients are 0.887 0 and 0.855 1 respectively, with prediction accuracy within practically acceptable engineering ranges. Finite element analysis of thermal performance for a vehicle door inner panel demonstrated slightly superior thermal properties using the optimized composite material selected through the proposed method, along with significantly improved R&D efficiency, validating the effectiveness of the approach. This provides important theoretical guidance and methodological reference for rapid development, cost reduction, material substitution, and green design of future automotive composites.