薄壁的

The basic approach of protecting people from being hurt or killed in an accident is to improve crashworthiness of vehicles. This paper starts with discussing theories and methods for vehicle passive safety design, which included experiential methods, analytic methods, multi-body dynamics methods, crash test methods and the finite element method. Emphasis will be paid to the basic FEM theories and algorithms of impact problems. Topics discussed include the governing equation, element discretization, hourglass control, time integration, material model, shell element algorithms and contact-impact algorithms. For more reliable simulation results, this paper then conducts study on how to accurately get material model parameters by combining the FEM method with experimental method, and develops relevant material test machine and parameter calculating software. Based on that, basic typical impact simulation and test validation study are conducted. On the basis of the above work, the paper studies the thin-shell structures'crashworthiness, which was affected by the following factors: spot-weld features, shell thickness, cross-section and pre-deformation. As to vehicle parts'crashworthiness, the paper conducts simulation study of designing energy-absorbing steering system and adaptive airbag system. A practical energy-absorbing steering wheel is designed as an example. In further depth research, the paper suggests several inverse quantificational methods for vehicle crashworthiness design based on the ideal crash characteristics. The above theories and methods are applied with good results through several practical vehicles' crashworthiness design and improvement.

文中对汽车碰撞安全性的设计理论和方法进行了归类和总结，其中包括经验法、解析法、多刚体动力学法、试验法以及有限元方法等；重点介绍了碰撞有限元法的基本理论和有关算法，涉及到有限元求解控制方程、单元离散、沙漏模态控制、时间积分、材料模型和应力修正、薄壳单元算法以及接触碰撞界面算法等，探讨了有限元计算中的材料模型参数获取技术，开发了相应的材料试验装置及材料模型参数反求软件，在此基础上进行了基本的碰撞仿真算例和试验对比研究；文中通过应用有限元方法研究了薄壁构件的碰撞吸能特性，指出了设计薄壁吸能构件时需要考虑的几个主要影响因素，即焊点、壁厚、横截面和预变形等；在关于车辆部件的碰撞安全性能设计中进行了吸能转向机构和自适应安全气囊的仿真研究，提出了吸能转向机构和自适应安全气囊的仿真研究方法；文中最后探讨了整车碰撞性能的设计与改进方法，提出了以理想碰撞特性为目标，采用分段加速度或者根据碰撞时间进行设计的反推设计法、部件吸能仿真优化设计法等量化设计方法，并通过综合应用文中所讨论的相关技术进行了整车碰撞性能的设计与改进实例研究，所选定的车型是大众化的普通轿车和碰撞安全性基础较差的微型面包车，研究结果表明，本文所提出的设计与改进方法是适用而有效的，具有重要的工程实用意义和价值。

Steel Truss.It is the load-bearing part in the roof structure. It can be triangle, trapezoid, shuttle and three-hinged. Angle bar steel, thin steel sheet, round bar and square bar can be used to manufacture it.

桁架：桁架是屋盖结构中主要承重构件，桁架的形式有三角形，梯形，梭形，三铰捞等，可采用角钢薄壁型钢，园管，方管等来制作。

That is to say, when the inclination angle of the localized deformed band is predicted to be , the localized deformed band cannot be observed in experiments.

即薄壁圆筒在扭转作用下局部变形带的倾斜角度为九十度时，不可能观察到局部变形带。

The experimental investigation on vibration characteristics of thin cylindrical shell with axial symmetry has been performed.

本文对轴对称薄壁壳结构的振动特性进行了试验研究。

Cold formed steel ...小型钢琴baby grand

冷弯型钢是一种经济的截面轻型薄壁钢材，。。。

However, bleb thinning and bleb - related infection after MMC surgery, and additional problem can be anticipated with longer follow-up.

然而，MMC术后薄壁滤过泡和滤过泡相关的感染以及其他问题尚需长期随访。

The performance of seepage prevention is an important index of the pond of thin wall of concrete.

防渗性能是混凝土薄壁水池的一项重要指标。

The wall has no support during the construction stage and the calculationbased on the national standard GB 50018-2002 (Technical code of cold-formedthin-wall steel, structures) should be reliable and safe. The crankle destabilizationof the studs with cold-formed channel section should be taken into account whencalculating the load-carrying capacity. The warpings at both ends of the sectionshould be calculated without any constraint when converting the crankledestabilization into the slenderness rationλ_w.

墙体在施工阶段基本为无墙体支撑，此时，按现行国标《冷弯薄壁型钢结构技术规程》(GB 50018-2002)规定计算是可靠、偏安全的，在计算其承载能力时应考虑单轴对称冷弯卷边槽钢截面立柱弯扭失稳，在计算立柱弯扭失稳换算长细比λ_w时，截面两端翘曲宜按不受到约束条件计算。

The results showed that there existed variation among eucalypt families in wood physical-mechanical properties and wood chemistry. There were significant differences among E.pellita families、E.grandis families and E.urophylla譋.grandis clones in wood colors as well as between Strains and within trees.The variation of the surface wetability of wood between E.grandis families and E.urophylla譋.grandis clones were significant.Even in the same families level or clones level,there still existed the same regulation. The degree of collapse of eucalypt had a large relation in the amount of tylosis in vessel and vestured pits on the cell wall of vessel. The more rich tylosis and vestured pits in vessels,the more probability to occur collapse for eucalypt.The biggest moment collapse was probably the critical point of the drying degrade.During the fomulation of drying technology,it is necessary to adopt moderate condition to make the vessels which had formed the biggest moment collapse at the biggest moment collapse resume,especially to prevent the permanent set.At the normal temperature level,the main factors which influenced residual collapse were the contents of ray parenchyma and axial parenchyma .Nearly all the cells joined the course of forming the moment collapse and biggest moment collapse.Interval drying was fit for eucalypt plantation which was easier to make collapse.

研究表明：桉树不同家系间木材物理力学性质和化学组成存在差异；粗皮桉家系间、巨桉家系间、尾巨桉无性系间材色存在显著差异，株间、株内木材材色存在变异；桉树木材表面润湿性在巨桉家系间、尾巨桉无性系间存在着显著差异，在同一家系或同一无性系中，株间和株内也存在着相同的变化规律；桉材皱缩程度与其导管中侵填体的多少和导管壁上纹孔具有的附物多少密切相关，侵填体含物越丰富，纹孔附物越多，桉材越容易皱缩；最大瞬间皱缩是能产生更大干燥降等的临界点，在制定干燥工艺时，必须在最大瞬间皱缩发生时，采用温和条件，使已产生最大瞬间皱缩的细胞尽可能多的恢复，尤其不能使其产生永久变定；在常温条件下，影响残余皱缩的主要因子是射线薄壁细胞和轴向薄壁细胞含量；而对于瞬间皱缩和最大瞬间皱缩，几乎所有细胞都参与它们的形成过程；对于易皱缩的桉树木材，间歇干燥是最有前途的干燥方法。

Results For callus induction of leaf explants of C. orchioides, dark treatment gave better results compared to light treatment; among the media tested, the suitable phytohormone combinations were 2.0 mg/L 2, 4-D or 6-BA 1.5 mg/L 2, 4-D 2.5 mg/L, and 300 mg/L CH 0.2% AC was good for plantlet regeneration from leaf explants. The callus from leaf explants mainly originated from midrib. The parenchyma cells near epicuticle of midrib firstly were initiated to division. Then the parenchyma cells of vascular bundle sheath and mesophyll cells on each side of vascular bundle were also divided to form callus.

结果对仙茅叶片的愈伤诱导，黑暗的效果好于光照；在所试验的培养基成分中，适宜的激素配比是2.0mg/L2，4-D或6-BA1.5mg/L 2，4-D2.5mg/L，并且附加300mg/L水解酪蛋白和0.2%活性炭，对于仙茅叶片的离体成苗较好；培养后，愈伤组织主要由叶片的中脉产生，位于中脉上表皮内侧的薄壁细胞首先启动分裂，随后维管束鞘薄壁细胞及其外侧的叶肉细胞也启动分裂，参与愈伤组织的形成。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐