多尺度信息融合的船舶外板检测三维标志点识别方法

针对船舶外板开展数字化检测技术研究对提升船舶外板智能制造水平具有重要意义。为解决船舶外板检测参考点坐标获取问题,提出了一种识别三维标志点的方法,可在船舶外板数字化检测过程中为实测点云和模型点云的匹配提供参考坐标信息。该方法针对船舶外板结构特点和形面测量需求,设计三维标志点的几何结构。此外,结合三维标志点自身多种特征和周边结构差异化特征,将标志点多种尺度信息进行融合,实现对标志点的精准识别。最后通过标志点测量数据计算对应船舶外板上定位点的三维坐标。通过试验验证了在所提出的方法在三维标志点识别方面具有准确性高、定位精准的优点,将大幅提升船舶外板数字化检测的效率。     

某汽车燃料箱隔热板翻边成形工艺设计及研究

目的 为了成形高质量、少缺陷的汽车燃油箱隔热板.方法 采用整体翻边-局部反拉深的工艺方法,以隔热板曲面凸台圆角处的最大减薄率为试验指标,采取正交试验及极差分析确定最优成形工艺参数,并利用有限元数值软件对其成形过程进行模拟.结果 各因素对曲面凸台圆角减薄的影响主次顺序为:凸模下压速度、摩擦因数、凸模与顶出块夹紧力,最优成形工艺参数组合为:下压速度为10 mm/s、摩擦因数为0.12、夹紧力为40 kN.由等效应变结果分析得出,随着变形量的增加,左侧翻边曲面等效应变分布大于右侧,两侧翻边曲面交接处也积累了较大应变.实际成形件的最大减薄率为凸台位置的17.1％,满足生产要求.结论 在最优工艺参数下生产出合格隔热件,实际成形件的减薄情况与模拟结果基本一致,验证了模具设计和模拟的准确性,这对于成形结构复杂的异形构件具有一定的指导意义.     

Study of the flexural performance and a novel calculation formula for the degree of composite action for precast concrete sandwich panels

This study investigates the flexural performance and degree of composite action (DCA) of precast concrete sandwich panels (PCSPs) with four types of connectors. Five full-scale specimens were designed, and 4-point bending tests were performed. The specimens included four PCSPs utilizing glass fiber reinforced polymer (GFRP) truss connectors, steel truss connectors, concrete rib connectors, and GFRP pin connectors, respectively, along with a solid panel (SP). The results indicated that the flexural performance and DCA provided by the four types of connectors followed an ascending order as follows: GFRP pin-type connectors, GFRP truss connectors, steel truss connectors, and concrete rib-type connectors. Moreover, the study presented a novel method for calculating DCA, namely, the neutral axis method, which was compared with the displacement and strain methods. The reasonableness and accuracy of the neutral axis method in calculating DCA during the linear elastic stage were verified. Results indicated that the neutral axis method provided more precise and reasonable DCA that closely matched the experimental results compared with the displacement and strain methods. Additionally, the neutral axis method was simpler to calculate DCA and had a broader range of applications. Finally, the study provided recommendations for the optimal application scenarios of each calculation method.     

Calculation Concept for Wood-Based Components in Mechanical Engineering

Herein, an approach is described for a calculation concept to close the gap between lightweight construction and necessary safety for structural components made of wood materials with use in mechanical engineering. The calculation of wood-based materials represents a challenge due to the orthotropic material behavior and the many influencing parameters on the mechanical properties. The main objective of the considerations is to predict the mechanical component behavior as precisely as possible. In the next step, the designer can use the results of the calculations to make statements about the component safety. The analyses of this article are part of the joint project “Wood-based materials in mechanical engineering (HoMaba)”.     

关注工业设计中的木质产品

回顾了木材使用史,提出了目前环境恶化资源匮乏的情况下,仍然对木质产品设计重视不够的问题;在结合木材的设计特性和关键技术的突破,介绍当前国际上对木质产品的关注以及现有的木质产品设计环境后,阐明木材十分契合绿色设计和可持续设计发展方向的观点;呼吁设计从业者和相关研究者积极参与到木质产品的设计研发和关键技术的突破创新工作中,更多地关注工业设计中的木质产品。     

高超音速飞行器表面板的非线性颤动(英)

在飞行器和宇宙飞船的设计过程中，表在板的空气动力颤动是个重要的值得深入考虑的问题．是近面世的纤维加强型复合材料已诮用在高超音速飞行器的表面板结构中．在空气动力压力和空气动力加热的综合作用下，这些表面板可以承受极其复杂的震颤运动．科技工作者为预测和研究这种颤动做了大量的工作．本文阐达了颤动问题的研究现状及发展方向．     

Preparation of façade panels based on alkali-activated waste mineral wool,their characterization,and durability aspects

Mineral wool is a widely used insulation material and one of the largest components of construction and demolition waste, yet it mainly ends up in landfills. In this work, we explored the potential recycling of waste stone wool in the pilot production of alkali-activated façade panels. The current work shows mechanical properties, SEM-EDS, and mercury intrusion porosimetry analyses for three different mix designs used for the preparation of façade panels. They are all composed of waste stone wool and differ in the amount of co-binders (local slag, lime, metakaolin, and/or fly ash) selected by the preliminary studies. In this study, co-binders were added to increase early strength and improve the mechanical properties and freeze–thaw resistance. The mechanical properties of each were measured up to 256 days, different durability tests were executed, and, by evaluating the mechanical properties, microstructure, and workability of the mortar, the most suitable mix was selected to be used for the pilot production. In addition, the leaching test of the selected mixture showed no exceeded toxic trace elements and therefore got classified as non-hazardous waste after its use.     

Ultrathin Wood-Derived Conductive Carbon Composite Film for Electromagnetic Shielding and Electric Heating Management

Recently, wood-based composites have absorbed widespread concern in the field of electromagnetic interference (EMI) shielding due to their sustainability and inherent layered porous structure. The channel structure of wood is often used to load highly conductive materials to improve the EMI shielding performance of wood-based composites. However, there is little research on how to use pure wood to prepare ultrathin EMI shielding materials. Herein, ultrathin veneer is obtained by cutting wood in parallel to the annual rings. Then, carbonized wood film (CWF) is prepared by a simple two-step compressing and carbonization. The specific EMI shielding effectiveness (SSE/t) of CWF-1200 with an ultrathin thickness (140 µm) and high electrical conductivity (58 S cm⁻¹) can reach 9861.41 dB cm² g⁻¹, which is much higher than other reported wood-based materials. In addition, the zeolitie imidazolate framework-8 ( ZIF-8) nanocrystals are grown in situ on the surface of the CWF to obtain CWF/ZIF-8. CWF/ZIF-8 exhibits an EMI shielding effectiveness (SE) of up to 46 dB and an ultrahigh SSE/t value of 11 330.04 dB cm² g⁻¹ in X band. In addition, the ultrathin CWF also shows an excellent Joule heating effect. Therefore, the development of ultrathin wood-based film provides a research basis for wood biomass to replace traditional non-renewable and expensive electromagnetic (EM) shielding materials.     

无醛板与净醛板在实际房间中的环保性能

市场上的无醛板和净醛板两种板材均以实验室检测报告为依据，称甲醛散发较低，且后者还称可净化室内空气中的甲醛。本研究选取实际房间作为研究场所，测试无醛板和净醛板的甲醛散发量及净醛板的甲醛净化能力。结果显示，两种板材散发的甲醛均较少，但未检测到净醛板在实际房间中的甲醛净化效果。