This study addresses the challenge of temperature non-uniformity during carbon fibre-reinforced polymer (CFRP) composite patch repair, which compromises curing quality and process efficiency. A coupled heat transfer–curing kinetics finite element model was developed and experimentally validated to investigate the heat sink effect of support structures. Key findings reveal that temperature differences concentrate near aluminum components and increase with curing temperature. For the present scarf-repair configuration, global sensitivity analysis identified the second-stage holding temperature (T2) and heating rate (r2) as the dominant factors governing temperature uniformity, whereas the holding times (dt1 and dt2) primarily determine the total curing time (ttotal). A novel multi-objective optimization framework combining optimal Latin hypercube sampling, radial basis functions, and NSGA-II was established. The optimized curing profile achieves a surrogate-predicted reduction of 22.5% in maximum temperature difference (22.0% when confirmed by high-fidelity finite element verification) and 36% in total curing time, while maintaining a minimum degree of cure above 0.98. These results provide a validated, surrogate-based framework for designing curing protocols that resolve metal-induced thermal non-uniformity in composite repairs without sacrificing cure quality.

Hollow fan blades made of titanium alloy are widely used in turbofan engines, and the residual stress (RS) inside the blades directly affects the performance of the blades and even the engine. Therefore, it is crucial to measure and study the RS distribution of titanium alloy hollow fan blades. This paper aims to investigate the RS distribution on the cross-section of a wide-chord hollow fan blade made of Ti-6Al-4 V titanium alloy. The multiple-cut contour method is utilized to determine the RS. A theoretical model of the multiple-cut contour method for fan blades is established, and the specimen was cut three times, followed by contour measurement of the cut planes, data processing and elastic finite element analysis. The RS map of the three cut planes is finally presented. The normal RS on three cross-sections of the fan blade is uniformly distributed, ranging from -50 MPa to 50 MPa. The normal RS distribution at different positions for the hollow fan blade can be obtained by the proposed multiple-cut contour method. The findings of this research provide a comprehensive insight into the distribution of RS in wide-chord hollow fan blades made of Ti-6Al-4 V titanium alloy.

Important estimates were made of the cohesive zone mode (CZM) characteristics used to predict the fracture of Elium composites processed at various temperatures in this study. First, tests for the end notched flexure (ENF) and double cantilever beam (DCB) on composites processed at different temperatures (24°C, 50°C, and 80°C) were performed. Based on the experimental results, the numerical models of damage evolution were developed. And six pairs of cohesive parameters (cohesive strength and cohesive stiffness) to the specified fracture energy release rates were obtained. Then, a Tsai approach was developed to predict the cohesive strength of the Elium composite with various process temperatures based on the obtained parameters. In order to predict the delamination behavior of the Elium composite, the obtained cohesive parameters were then used to a numerical model of short beam shear (SBS). The peak force of the simulations was discovered to be consistent with the outcomes of the tests. The findings served as a reference for damage assessments of Elium composites processed at various temperatures.

In the machining of monolithic components, machining distortion is a severe issue. The presence of initial residual stress is a major contributor to machining distortion. This paper proposes an approach to control the machining distortion of long beam parts by optimizing the workpiece structure before the start of the finishing stage, i.e. the transition structure. The first step is to establish a machining distortion analytical model for long beam parts with an identical cross-section, which is based on reasonable assumptions such as material linear elasticity and ignoring the influence of cutting heat. Then, an optimization model for the cross-section of the transition structure is developed, with the objective function defined as the minimum difference between the predicted distortion of the final part and the transition structure. Finally, a U-shaped beam is designed, followed by numerical simulation and machining experiments for verification. The theoretical maximum distortion of the optimized transition structure and the final part are −0.174 and −0.1782 mm, respectively, with a relative error of 2.9 %. The results of machining experiments and finite-element simulation demonstrate the effectiveness of the proposed model.

加工变形一直是困扰航空制造业的一个严重问题.文章以航空长梁类零件为研究对象,分析了由材料内部初始残余应力引起的弯曲能量的演变,定义了加工变形稳定性和弯曲势能指标,提出了一种通过优化材料去除顺序来控制变形稳定性的方法.最后,采用实例进行理论分析、仿真分析和加工试验验证.结果表明,通过优化材料去除顺序,零件精加工阶段变形稳定性显著提高.

为了准确地预测Elium树脂的放热性能,基于瞬态非线性热传导方程的树脂固化模型,利用Abaqus仿真软件,建立了 Elium树脂固化有限元模型,并对不同厚度Elium树脂的固化过程进行模拟和实验验证.结果表明固化温度的模拟计算结果与实验结果一致,固化峰值温度随着树脂厚度的增加呈现非线性增加趋势,当固化峰值温度接近100 ℃时,树脂中产生气泡,为优化Elium复合材料成形工艺提供了理论依据.

The aircraft manufacturing industry faces a severe problem of machining distortion. Machining distortion is caused primarily by residual stresses. The energy conversion during the machining process is the essence of residual stress leading to machining distortion. This paper uses the energy principle to analyze the mechanism of machining distortion of long beam parts, pointing out that during stress redistribution, part of the strain energy is released to do work, and the result of stress redistribution is consistent with the principle of minimum potential energy. The energy concept is used to develop a theoretical model of stress redistribution. A theoretical model of stress redistribution based on the energy principle is proposed. A model is proposed for predicting machining distortion during the machining of long beam-like parts, and the model's accuracy is demonstrated using a case study.

By adaptively releasing deformation during machining, floating clamping significantly raises the machining quality of aircraft structural parts. The fundamental issue to be resolved is how to precisely control the clamping action of the floating fixtures. In this study, the machining process of aircraft beams was studied, utilizing the finite element method (FEM) from the perspective of strain energy evolution. The study found that the increment of deformation and the variation of the strain energy between adjacent removed layers of the material showed the same trend of change, and targeted clamping loosening at the stage of an excessive strain energy evolution gradient is beneficial to reducing the final deformation of the workpiece. Therefore, a clamping action control method based on strain energy evolution gradient regulation is proposed, and a clamping action control strategy of floating fixtures was formulated. Furthermore, a cutting experiment was carried out, and the results showed that the maximum deformation of the aircraft beam using the clamping action control strategy was only 0.112 mm, which was reduced by 74.6% compared to traditional clamping.

Machining distortion has been a long-term obstacle in the machining of aircraft monolithic parts. Furthermore, its stability has to be considered. The machining distortion stability represents the fluctuation degree of the machining distortion. This paper investigates the evolution of elastic energy induced by initial residual stress inside materials, revealing that this evolution directly affects machining distortion. In this paper, the concept of machining distortion stability and bending potential energy is defined. By analyzing bending potential energy releasing, this study proposes a novel method for improving machining distortion stability through optimization of material removal sequence. Numerical simulation and milling experiments are performed to verify and validate the model, respectively. The results indicate that the machining distortion stability is significantly improved when optimized material removal sequence is applied. By controlling the machining distortion stability, the final distortion can be further reduced via re-machining the machining datum at the beginning of the finishing stage.

Owing to reliability and high strength-to-weight ratio, large thin-walled components are widely used in the aviation and aerospace industry. Due to the complex features and sequence involved in the machining process of large thin-walled components, machining deformation of component is easy to exceed the specification. In order to address the problem, it is important to retain the appropriate finishing allowance. To find the overall machining deformation, finishing allowance-induced deformation (web finishing allowance, sidewall finishing allowance) and initial residual stress-induced deformation were considered as major factors. Meanwhile, machined surface residual stress-induced deformation, clamping stress-induced deformation, thermal deformation, gravity-induced deformation and inertial force-induced deformation were neglected in the optimization model. Six-peak Gaussian function was introduced to fit the initial residual stress. Based upon the obtained function of initial residual stress, a deformation prediction model between initial residual stress and finishing allowance was established to attain the finishing allowance-induced deformation. In addition, linear programming optimization model based on the simplex algorithm was developed to optimize the overall machining deformation. Results have concluded that the overall machining deformation reached the minimum value when sidewall finishing allowance and web finishing allowance varied between 1 and 2 mm. Additionally, web finishing allowance-induced deformation and sidewall finishing allowance-induced deformation were 1.05 mm and 0.7 mm. Furthermore, the machining deformation decreased to 0.3–0.38 mm with the application of optimized finishing allowance allocation strategy, which made 39–56% reduction of the overall machining deformation compared to that in conventional method.

In the machining process of aircraft monolithic parts, the initial residual stress redistri-bution and structural stiffness evolution often lead to unexpected distortions. On the other hand, the stress redistribution and stiffness reduction during the machining process depend on the mate-rial removal sequence. The essence of the stress redistribution is releasing the initial elastic strain energy. In the present study, the influence of the material removal sequence on the energy release is studied. Moreover, a novel optimization method is proposed for the material removal sequence. In order to evaluate the performance of the proposed method, the mechanism of the machining dis-tortion is firstly analyzed based on the energy principle. Then a calculative model for the machining distortion of long beam parts is established accordingly. Moreover, an energy parameter related to the bending distortion and the procedure of the material removal sequence optimization is defined. Finally, the bending distortion analysis and material removal sequence optimization are performed on a long beam with a Z-shaped cross-section. Furthermore, simulation and experiments are carried out. The obtained results indicate that the optimized sequence results in a low distortion fluctuation and decreases the bending distortion.

Machining distortion is a recurring problem in the machining of monolithic aircraft parts. This paper aims to study the machining distortion minimization of monolithic aircraft parts. Firstly, the energy principle of machining distortion was analyzed. Then, a rapid prediction model of the final part distortion for beam parts was proposed based on the equivalent stress, and the initial bending strain energy contained in the final part was used to characterize the bending distortion risk of the final part. Numerical simulation and milling experiments verified the effectiveness of the proposed prediction model. The relative error between the experimental and calculated results does not exceed 26.5%. Finally, the influence of initial residual stress fluctuation, part geometry and the part location on part distortion was analyzed from the energy point of view. The obtained results indicated that the expected final part distortion can be minimized by adjusting these three factors.

The success of an autoclave process is related to the temperature characteristics of the mold. An inhomogeneous temperature field in the mold affects the quality of composite parts, which may lead to residual stress, voids, and other manufacturing defects of composite parts. In order to meet high-quality production demands, the temperature field in a mold should be investigated precisely. The temperature distribution in a large frame mold is critically evaluated in this work. Then, a method to control the temperature distribution in a large frame mold is proposed. A computational fluid dynamics (CFD) model of the autoclave process is developed to predict the temperature evolution of the large frame mold. The model is validated by experimental results, which shows good agreement with a relative difference of 5.92%. The validated CFD model is then applied to analyze the temperature distribution characters in the mold with different control conditions. The results show that the temperature difference decreases by 13.3% when the mold placement angle is changed from 180 to 168°.

为了实现CAD与CAIP(计算机辅助测量规划)的集成,提出了一种基于产品三维模型的CMM(三坐标测量机)测量点采样方法。该方法从产品的IGES文件中有效识别型面形状与边界定义,采用均匀采样与依曲率变化二次采样相结合的策略,针对各个型面类型制定专门的信息处理机制,实现测量点的自动采样,并通过转换在参数平面中判断采样点与裁剪区域的隶属关系,以有效剔除无效采样点;通过典型飞机部件外形曲面的采样点生成结果表明,该方法能有效应用于飞机的测量规划中。

文章提出了点云数据与CAD模型配准的三个预处理步骤：点云噪声过滤， CAD模型点云化和数据重采样。采用张量投票算法对原始点云数据过滤噪声，选用STL格式将CAD模型离散为点云格式，在CAD模型点云化和点云噪声过滤后，基于八叉树数据对两个数据集进行重采样，获得一个通用的解决方案。实验结果验证了文中算法的有效性。

在逆向工程领域中,随着非接触测量技术的发展,三维物体型面重建更加趋于简捷化。然而受设备测量范围的限制,大型件或复杂表面件需经多次测量才能获得其全场数据。因此,将多次测得的产品点云数据进行拼接、配准以到达坐标归一化对于型面重建质量具有重大意义。本文就三点法对多视测量数据的配准及ICP算法优化进行了研究,重点对三点法中标记点位置的求取算法进行了深入地探讨。通过对某机模型翼面进行多视点云数据的配准的检验,表明采用三点法能够得出较为理想的翼面数据。

Restricted by measurement range, measurement methods based on optical technology need to transform multi-view data into a global coordinate system to form complete expression of body being measured with large size and complicated shape. This paper focused on alignment of multi-view data and put forward recognition and calculation method of marked points from laser strips projected by laser sensor, as well as matching of marked point sets of different views with distance constraint method. Local measurement coordinate system was established by marked points of each view, which was applied to achieve pre-alignment of multi-view data. ICP method combined with the pre-alignment method was used to accurately locate data of different views.Experimental results showed that the method was rapid and stable, and could effectively extend measurement scope of linear structure light method.