堤基抗挤压稳定计算

在永宁江和东海塘土堤填筑施工中,均发现在堤身垂直荷载作用下,堤基发生挤压破坏情况,堤身下部基土沿着堤身外侧的平台或戗堤下一定深度处的通道中被挤压出去,使外侧地面隆起,堤身下沉,土堤结构破坏.本文根据现场实际,提出对这种挤压稳定的校核计算方法,结果与工程实际情况相当吻合,建议推荐使用.     

堤基防渗加固技术的应用

对堤基现行防渗加固方法作了介绍，并对各堤防渗加固方法的适用特点 进行了论述。     

非淹没丁坝坝头冲刷深度的计算

基于丁坝坝头水流结构 ,提出了坝头绕流挤压流动模式 ;由此根据有效局部水流连续原理 ,建立了丁坝坝头冲刷深度计算公式 ,该式涉及因素较全面 ,公式建立过程中所使用的数学模式清晰 ,物理意义明确 .经野外及室内资料验证表明 ,计算与实测结果较为吻合 ,具有较好的适应性     

Wear simulation of spur gears

This paper deals with prediction of wear in spur gears, which has been calculated using an approach in which the wear depth on a tooth surface is integrated over time using the Euler integration method. Variations in pressure distribution over the surface have been considered, as well as changes in curvature and surface profile of the teeth as they wear. The paper focuses on the use of an appropriate wear model for simulating wear using calculated conditions between high-performance slow-running lubricated spur gears. A numerical model for prediction of surface interaction of spur gears developed earlier by the authors has been applied as the basis for the simulation of wear using different wear models. Owing to the nature of the wear models, methods of calculating the contact temperature have been investigated for the specific case of interacting gear teeth. It was found that a linear wear model, when compared with a more complex oxidation model and with a model based on adsorption of lubricant molecules, satisfactorily predicts wear. It was also found that it is the geometry of the gears that causes sliding velocity to be the dominant wear-inducing factor, and so determines the general nature of the wear behaviour.     

带毂直齿圆柱齿轮精锻的实验研究——直齿圆柱齿轮精锻研究Ⅱ

本文实验研究了带毂直齿圆柱齿轮精锻时的金属流动和变形力,获得了金属流动规律及其对变形力的影响,提出了对制订精锻工艺有参考价值的结论,可供精锻带毂直齿圆柱齿轮的科研和生产应用。     

渐开线直齿圆柱齿轮非牛顿瞬态弹流润滑分析

齿轮的润滑设计都是应用理想牛顿流体的结果,但实际上,在中、轻载荷下Ree Eyring流体更符合实际。因 此研究齿轮在非牛顿润滑下的瞬态弹流机理,对于指导齿轮润滑问题的设计更具有工程实际价值。本文应用数值 稳定性好、收敛速度快和计算精度高的多重网格算法,得到了用Ree Eyring流体润滑的齿轮瞬态弹流问题的完全数 值解。     

Calculation of sliding power loss in spur gear contacts

An engineering-level calculation model for sliding power loss in spur gear contacts is presented. Teeth contact through the line of action is modelled as a constantly changing roller contact whose radius, speed, and load can be calculated from the gear geometry under the given operating conditions. The gear mesh cycle is approximated by a large number of elastohydrodynamic contacts. A constant film thickness and a Hertzian pressure distribution are assumed in each contact. The model includes non-Newtonian lubricant behaviour together with temperature and mixed lubrication effects in contact. The numerical solver is reasonably fast in evaluating effectively the sliding power loss dependence on the essential gear and lubricant parameters. The features and behaviour trends of the calculated sliding power losses have a close similarity with published results obtained from measurements and experiment-based power loss models with mineral oil. The limiting shear stress of the lubricant is observed to have an essential role in the power loss behaviour especially at high loads.     

浅议渭河下游河道治理

从渭河洪水的特点、渭河下游河道和堤防工程的现状等方面对渭河下游洪水造成的灾害原因进行初步探讨,提出相应的工程措施,以期对今后渭河下游的河道治理工程提供参考。     

大模数高凸台圆柱直齿轮净成形试验研究

采用浮动凹模-梯形槽约束分流方法,设计了大模数高凸台圆柱直齿轮的闭塞式精密成形模具,对其成形过程进行了三维刚粘塑性有限元数值模拟,并进行了试验研究.结果表明,采用浮动凹模-梯形槽约束分流有利于降低成形力,且能得到良好的充填效果和齿轮外观精度及完整的金属流线.试验结果与有限元数值模拟结果能很好地吻合.     

黄河堤防边坡稳定性的可靠度分析

为了更能准确地评价黄河堤防边坡的稳定性,对可靠度理论在黄河堤防边坡稳定性分析中的应用进行了研究;可靠度理论是建立在概率统计基础上的,充分考虑了土体抗剪强度参数c、ψ值的变异性及其相关性等对边坡稳定的影响;利用编制的蒙特卡罗法边坡稳定可靠度分析程序进行了工程实例计算,得出的评价边坡稳定性的可靠指标比定值法得出的安全系数更能反映工程实际情况,具有极其重要的应用推广价值.