共查询到20条相似文献,搜索用时 203 毫秒
1.
王敏中 《应用数学和力学(英文版)》1985,6(1):87-92
In this paper we obtain uniquely the solution of Saint- Venant’s problem under theassumption of ∂m/∂zmσz=0(m≥2) for noncircular prismatic bars. 相似文献
2.
Let G be a graph,k1,…,km be positive integers. If the edges of graph G can be decomposed into some edge disjoint. [0,k1]-factor. F1,…,[0,km]-factor Fm, then we can say F={F1,…,Fm, is a [0,ki]m1-factorization of G. If H is a subgraph with m edges in graph G and |E(H)∩E(Fi)|=1 for all 1≤i≤m, then we can call that F is orthogonal to H. It is proved that if G is a..[0,k1+…+km-m+1]-graph, H is a subgraph with m edges in G, then graph G has a. [0,ki]1m-factorization orthogonal to H. 相似文献
3.
林拜松 《应用数学和力学(英文版)》1984,5(4):1549-1555
In this paper, we proposed a new cr tenon or mixea-moae brittle fracture, i.e., the strain energy criterion, which can be stated as (KⅠ/KⅠc)2 +(KⅠ/KⅠc)2+(KⅡ/KⅡc)2=1. This criterion is shown to be in good agreement with known experimental data.In this paper, an experimental criterion:(KⅠ/KⅠc)m+(KⅡ/KⅡc)n=1, 1≤nm≤2.is also proposed. 相似文献
4.
5.
In this study, compressive tests of the bones along the axial direction have been carried out on some wet specimens of the right femur and humerus, from which there have been obtained the elastic modulus of femur E=9.98×109N/mM2 and.’that of humerus E=11.37×109N/m2 Also comparisons and discussions have been made with reference to the available data reported abroad and at home.As indicated in this paper, bone tissues obviously possess viscoelastic properties. Their hysteresis loops are shown in Fig. 3 far and (b) and some mechanical phenomena observed during the test are illustrated elsewhere. 相似文献
6.
张鹏 《应用数学和力学(英文版)》1989,10(12):1137-1149
There are N domains Dj(j=0,1,...,N-1) of different physical parameters in the whole space and their interfaces Sj,i+1 are non-horizontally smooth curved surfaces. The following boundary problem is called Hclinholiz boundary problem:V2H(1)+KjH(1)=0 (j=0,1,…,N-1)(H(0)-H(1))=δ(S) (δ(S):generalized function)(H1-Hi+1)=0 (j=0,1,…,N-2)The analytical solution of the above problem is given in this paper. 相似文献
7.
甘肃省舟曲8.7特大泥石流调查研究 总被引:7,自引:0,他引:7
本文通过对甘肃省舟曲县城后山三眼峪沟和罗家峪沟特大泥石流灾害的现场调查,从泥石流形成的地形、地质和降雨条件入手,分析了特大泥石流灾害的特征与成因:三眼峪沟和罗家峪沟泥石流形成区在2010年8月7日23~24时的1h降雨量达77.3mm,暴雨形成强大洪水依次冲毁两条沟内的天然堆石坝和人工拦挡坝,形成规模巨大的高容重黏性泥石流,泥石流冲出总量和泥沙总量分别为 144.2×104m3和97.7×104m3; 泥石流携带具有强大冲击力的巨石冲毁房屋5500余间; 在白龙江内形成长约550m,宽约70m,高约10m的堰塞坝并形成堰塞湖,堰塞湖回水长3km,使县城一半被淹; 泥石流造成1744人死亡和失踪。分析研究表明,三眼峪沟和罗家峪沟泥石流如果在近期遭遇强降雨还会暴发泥石流,但规模比87特大泥石流小;如果强降雨发生在数年后,暴发的泥石流规模比87特大泥石流略小;在20a或更长的时期内,没有发生新的地震影响下,在三眼峪沟和罗家峪沟经历一次大规模泥石流暴发后,泥石流的规模将回到汶川地震前的水平。 相似文献
8.
Thomas B. Goudoulas Eleftherios G. Kastrinakis Stavros G. Nychas 《Rheologica Acta》2003,42(1-2):73-85
An investigation of the rheological properties of dense lignite-water suspensions is reported here in order to evaluate the
parameters that affect the rheology of these suspensions. Different types of particle size distributions were achieved via
wet grinding with particle sizes down to 1 μm. Polyelectrolytes and surfactants were used to improve the stability and rheology
of suspensions. The achieved solid volume fraction, φ, with acceptable rheological behavior was 0.45, while the ratio of φ/φ
m
was close to 0.85; φ
m
is the maximum solid volume fraction. Various types of flow tests were performed on lignite-water suspensions with various
preshear times and stress levels. Typical shear rates varied in the range between 10–2 to 102 s–1. The low shear behavior was found to be quite different from the high shear behavior for the most concentrated suspensions,
with a plateau value at low shear rates indicating the appearance of a yield stress. These plateau values, however, depend
on shear history, which is responsible for the development of different structures in the sample. The viscosity curves corresponding
to the ascending and descending parts of the flow curve were found to be different; these flow curve parts can be described
either by well established models or by modified ones. The non-Newtonian time dependent behavior of the lignite-water suspensions
is attributed to the high value of the ratio φ/φ
m
, the polydispersity of the particle size distribution, and the non-spherical shape of the lignite particles. 相似文献
9.
首先基于椭圆颗粒接触点的运动关系推导出新的平均纯转动率(APR)表达式,并将其引入到已有的描述圆形散粒体流动特性的双滑移转动率模型(DSR2模型)中;而后采用改进的NS2D离散元程序对长短轴比例分别为1.4和1.7的椭圆颗粒堆积体进行一系列不排水单剪试验,验证以椭圆颗粒为基础的离散元方法模拟砂土流动特性的可行性及DSR2模型的合理性。数值试验及已有成果表明,以椭圆颗粒为基础的NS2D程序能够模拟砂土的流动特性,对圆形和椭圆形颗粒体系,DSR2模型均能很好地预测运动模型中转动率参量的变化情况;APR是联系连续介质力学和离散介质力学的重要参数,它将二者有机结合成一个整体。 相似文献
10.
陕西凤县地质灾害易发性评价研究 总被引:6,自引:0,他引:6
区域地质灾害易发性评价是地质灾害早期预警的基础。为了探索秦岭山区区域地质灾害易发性评价方法,文中在陕西凤县1 :5万地质灾害详细调查和数据库建设的基础上,详细分析了地质灾害的发育分布规律及影响因素,利用GIS技术结合信息量模型方法完成了凤县地质灾害的易发性评价区划。结果显示:凤县地质灾害分布主要与河流侵蚀、植被覆盖率及人类工程活动相关。根据评价结果将凤县地质灾害易发性划分为4个等级,其中,地质灾害高易发区面积190.3km2,占全县总面积的6.0%; 中易发区面积642.0km2,占20.1%; 低易发区面积1314.5km2,占41.2%; 基本安全区面积1040.1km2,占32.6%。评价结果可为凤县土地利用规划和地质灾害防治规划提供依据,并可为秦岭山区城镇地质灾害易发性评价提供思路和方法。 相似文献
11.
12.
14.
15.
Miao Yingkai 《力学与实践》2015,37(5):658
雨伞是依靠伞柄上弹簧的弹力撑开的, 同时弹簧也将自身举了起来. 在重力的作用下, 弹簧怎么可能自举呢?伞骨和弹簧组成的特殊结构是弹簧能够自举, 雨伞能撑开的关键. 本文与实践相结合, 运用力学知识对雨伞自动撑开的原理进行了分析. 相似文献
16.
17.
用电阻量测方法研究蠕变状态下的金属损伤 总被引:3,自引:0,他引:3
Lokochtchenko A. M 《力学学报》1992,24(2):191-196
本文建议一种量测蠕变下金属损伤的方法。与其它方法相比,这个方法可用于进行在蠕变试验过程中的损伤测量,而无需使试件卸载或冷却。用此方法对试验数据进行加工就可得到在蠕变过程中的试验损伤曲线。对这些曲线的分析导致结论:材料破坏时的损伤是所加应力的递减函数。这一结论是以前所得理论结果的试验验证。 相似文献
18.
19.
井眼轨迹控制工具主轴载荷与造斜能力关系研究 总被引:1,自引:0,他引:1
井眼轨迹控制工具是随钻实时完成导向功能的一种导向式钻井工具.在复杂工况下,主轴承受钻压、扭矩和偏置机构作用力等,十分复杂.在课题组前期研究的基础上,对样机主轴的力学行为开展了进一步的研究,在建立主轴静力学模型的基础上,分析了工具外壳刚度、偏置机构安装位置等因素对主轴力学行为与造斜能力的影响规律.研究发现,主轴下端偏转角、偏心机构作用力和最大截面弯矩会随着偏心位移增加呈线性增加;随着外壳刚度的增加和偏置机构安装的位置与上支撑轴承之间距离的增加,工具造斜能力也会增强;通过分析偏置机构安装位置和外壳刚度对主轴力学行为的影响规律发现,随着外壳刚度的增大和偏置机构安装位置与上支撑轴承之间距离的增大,主轴最大截面弯矩也会增大.最后,给出了最佳的外壳刚度与偏置机构安装位置建议. 相似文献
20.
本文采用非线性滞后函数模型,对于粘弹性系统的随机振动问题,应用等效线性化和方差分析的方法进行了分析研究,给出了白噪声激励下的响应计算解。 相似文献