Failure mechanisms and bending strength of Fuchsia magellanica var. gracilis stems

In the course of biological evolution, plant stems have evolved mechanical properties and an internal structure that makes them resistant to various types of failure. The mechanisms involved during damage development and failure in bending are complex and incompletely understood. The work presented builds on a theoretical framework outlined by Ennos and van Casteren, who applied engineering mechanics theory to explain why different woody stems fail in different ways. Our work has extended this approach, applying it to a detailed analysis of one particular species: Fuchsia magellanica var. gracilis. When subjected to three-point bending, stems of this species exhibited one of two failure mechanisms: a plastic hinge or a greenstick fracture. We developed a predictive model using a computer simulation and a mathematical analysis using the theory of plastic bending. Required material properties were obtained from tests, the literature and imaging techniques. We found that greenstick fractures are more likely to occur in more lignified stems with a higher density. We discovered a new failure mode: an internal crack caused by tensile transverse stress. This work helps in understanding how plants have evolved their bending resistance and may assist in the creation of novel engineering structures inspired by these principles.     

轻型混凝土夹芯板的开发研究

轻型混凝土夹芯板是由上下两层陶粒混凝土层和中间的聚苯乙烯保温夹芯层组成 ,通过试验发现 ,由于这种板材自重小 ,刚度大 ,整体性好 ,所以在使用过程中具有挠度发展缓慢的优点 ,本文将具体介绍本次试验过程和通过试验分析得出的结论     

精密仪器横轴的结构工艺性

根据设计的需求，在保证零件精度及正常使用的前提下，改进了零件的结构工艺性，使零件的生产能满足工厂的实际加工情况及经济性需求。     

电镜用偏转线圈空间磁场分布的计算

本文根据毕奥－萨伐尔定律，给出了分段集中绕制的矩形，环形线圈空间磁场分布的解析表达式，能方便地用于电镜偏转系统的设计。     

计算细长压杆临界力的“统一静力法”

本文建立了细长压杆统一的小挠度微分方程，利用该方程及边界条件，推导出各种交承压杆的欧拉公式。     

对温度裂缝与沉降裂缝判断和处理实例分析

文章通过工程实例判断温度裂缝和沉降裂缝,在分析产生裂缝机理的基础上,对裂缝处理和防治提出若干见解。     

斜齿轮螺旋角的测绘

针对斜齿轮螺旋角的测绘难度大,利用齿根圆在齿轮使用过程中其尺寸基本不变的 原理,通过分析齿根圆与公法线的相互关系,提出一种测绘斜齿轮螺旋角的新型方法,并在实际中 得到验证,取得了较好的效果。     

转子回转件瓢偏度测量计算方法的商摧

转动机械转子上回转部件的端面瓢偏度是转子测量的重要项目之一。目前，在各类有关机械装配的专业技术书籍中，瓢偏度的定义基本相同，但其测量计算方法却不尽一致，本文针对这一问题对瓢偏度测量计算方法作一商榷。     

钢铜复合材料深加工变形力能参数研究

利用压力试验机和二辊轧机，在外力和压下方向平行于复合面的变形方式下进行了实验提出了确定变形区应力状态系数Ｑ＿ｐ的方法，建立了Ｑ＿ｐ数学模型。并对Ｑ＿ｐ模型进行了实验验证，表明模型精度较好。