Simulation and Experimental Study of Staple Line Reinforcement Surgery

The aim of this study was to evaluate the effectiveness of BM (basement membrane) and SIS (small intestine submucosa) composite extracellular matrix staple line reinforcement in surgical procedures through finite element modelling simulations and leak-proof performance experiments. The mechanical analyses of soft tissues with and without staple line reinforcement were performed by establishing finite element models of three tissues, namely, stomach, intestine and lungs, under the use scenarios of different anastomosis staple models;and the leak-proof performance of the staple line reinforcement was evaluated by simulating leak-proof experiments of gastric incision margins, intestinal sections, and lung incision margins in vitro. The results showed that the equivalent average stresses of the staple line reinforcement were increased by 20 kPa-68 kPa in gastric and intestinal tissues, and 8 kPa-22 kPa in lung tissues. and that the BM and SIS composite extracellular matrix staple line reinforcement could strengthen the anastomotic structure, and at the same time disperse the high stresses of the anastomosed tissues, which could effectively reduce the postoperative complications such as anastomotic bleeding and anastomotic leakage, and provide a safer and more effective optimized design for surgical mechanical anastomosis. It can effectively reduce postoperative complications such as anastomotic bleeding and anastomotic leakage, and provide a safer and more effective optimized design for surgical mechanical anastomosis.

Static and Dynamic Analysis of Mooring Lines by Nonlinear Finite Element Method

This study has focused on developing numerical procedures for the static and dynamic nonlinear analysis of mooring lines. A geometrically nonlinear finite element method using isoparametric cable element with two nodes is briefly presented on the basis of the total Lagrangian formulation. The static and dynamic equilibrium equations of mooring lines are established. An incremental-iterative method is used to determine the initial static equilibrium state of cable systems under the action of self weights, buoyancy and current. Also the Newmark method is used for dynamic nonlinear analysis of ocean cables. Numerical examples are presented to validate the present numerical method, and examine the effect of various parameters.

STUDY ON THREE-DIMENSIONAL FINITE BODIES CONTAINING CRACKS USING THE FINITE ELEMENT METHOD OF LINES

The three-dimensional finite element method of lines is presented, and the basic processing description of 3D FEMOL in cracking questions is given in detail. Applications to 3D bodies with cracks indicate that good accuracy can be obtained with relatively coarse girds. In particular, application to the tension specimen shows very good agreement with the evaluation of stress intensity factors, which is better than the results of other methods. This implies a considerable potential for using this method in the 3D analysis of finite geometry solids and suggests a possible extension of this technique to nonlinear material behavior.

Higher-Order Line Element Analysis of Potential Field with Slender Heterogeneities

Potential field due to line sources residing on slender heterogeneities is involved in various areas,such as heat conduction,potential flow,and electrostatics.Often dipolar line sources are either prescribed or induced due to close interaction with other objects.Its calculation requires a higher-order scheme to take into account the dipolar effect as well as net source effect.In the present work,we apply such a higher-order line element method to analyze the potential field with cylindrical slender heterogeneities.In a benchmark example of two parallel rods,we compare the line element solution with the boundary element solution to show the accuracy as a function in terms of rods distance.Furthermore,we use more complicated examples to demonstrate the capability of the line element technique.

Cracking analysis of fracture mechanics by the finite element method of lines(FEMOL)

The Finite Element Method of Lines （FEMOL） is a semi-analytic approach and takes a position between FEM and analytic methods. First, FEMOL in Fracture Mechanics is presented in detail. Then, the method is applied to a set of examples such as edge-crack plate, the central-crack plate, the plate with cracks emanating from a hole under tensile or under combination loads of tensile and bending. Their dimensionless stress distribution, the stress intensify factor （SIF） and crack opening displacement （COD） are obtained, and comparison with known solutions by other methods are reported. It is found that a good accuracy is achieved by FEMOL. The method is successfully modified to remarkably increase the accuracy and reduce convergence difficulties. So it is a very useful and new tool in studying fracture mechanics problems.

Line-element based nonlinear adaptive piecewise compensating correction for LVDT sensors

In order to solve the linear variable differential transformer （LVDT） displacement sensor nonlinearity of overall range and extend its working range, a novel line-element based adaptively seg- menting method for piecewise compensating correction was proposed. According to the mechanical structure of LVDT, the output equation was calculated, and then the theoretic nonlinear source of output was analyzed. By the proposed line-element adaptive segmentation method, the nonlinear output of LVDT was divided into linear and nonlinear regions with a given threshold. Then the com- pensating correction function was designed for nonlinear parts employing polynomial regression tech- nique. The simulation of LVDT validates the feasibility of proposed scheme, and the results of cali- bration and testing experiments fully prove that the proposed method has higher accuracy than the state-of-art correction algorithms.

COMPUTATION OF STRESS INTENSITY FACTORS BY THE SUB-REGION MIXED FINITE ELEMENT METHOD OF LINES

Based on the sub-region generalized variationM principle, a sub-region mixed version of the newly-developed semi-analytical ＇finite element method of lines＇ （FEMOL） is proposed in this paper for accurate and efficient computation of stress intensity factors （SIFs） of two-dimensional notches/cracks. The circular regions surrounding notch/crack tips are taken as the complementary energy region in which a number of leading terms of singular solutions for stresses are used, with the sought SIFs being among the unknown coefficients. The rest of the arbitrary domain is taken as the potential energy region in which FEMOL is applied to obtain approximate displacements. A mixed system of ordinary differential equations （ODEs） and algebraic equations is derived via the sub-region generalized variational principle. A singularity removal technique that eliminates the stress parameters from the mixed equation system eventually yields a standard FEMOL ODE system, the solution of which is no longer singular and is simply and efficiently obtained using a standard general-purpose ODE solver. A number of numerical examples, including bi-material notches/cracks in anti-plane and plane elasticity, are given to show the generally excellent performance of the proposed method.

Mechanical response of transmission lines based on sliding cable element

In order to study the sliding characteristics when the cable is connected with the other rods in the transmission line structures,a linear sliding cable element based on updated Lagrangian formulation and a sliding catenary element considering the out-of-plane stiffness coefficient are put forward.A two-span and a three-span cable structures are taken as examples to verify the sliding cable elements.By comparing the tensions of the two proposed cable elements with the existing research results,the error is less than 1%,which proves the correctness of the proposed elements.The sliding characteristics should be considered in the practical engineering because of the significant difference between the tensions of sliding cable elements and those of cable element without considering sliding.The out-of-plane stiffness coefficient and friction characteristics do not obviously affect the cable tensions.

Einstein’s Non-Euclidean Line Element Theory and Quantum Mechanics Interpretation

In “The third speech on the wave mechanics” (1926), E. Schodinger pointed that the Hamilton-Maupertuis principle as a classical starting point of wave mechanics in the definition of generalized coordinate space line element, introduced the generalized non-Euclidean geometry, and finally obtained the wave equation including Laplace operator in the generalized non Euclidean geometry line element. At the 1927 meeting of the Prussian Academy of Sciences in Berlin, Albert Einstein read a paper entitled “Does Schodinger’s wave mechanics determines the dynamics of a system’s movement completely or only sence in statistics?”. In this paper, Einstein used the Schodinger equation to obtain a representation of the kinetic energy, and used the non-Euclidean line element of the Configuration space to define the velocity component of a single particle, and return to determinism. But Bothe pointed out that when people considered a system composed of two subsystems, the wave function of the whole system can be decomposed into two simple products of the wave function of the two subsystems, but the hidden variables are dependent on each other. Einstein be-lieved that this was not acceptable, gave up the publication of the paper on the non-European line hidden variables theory. In the long-term controversy with the Copenhagen school, Einstein was convinced that the probability interpretation of the wave function was indispensable because of the incompleteness of quantum mechanics, but not the wave function probability led to the incompleteness of quantum mechanics. Any attempt to seek a complete explanation of quantum mechanics is inevitable to change the current formal system of quantum mechanics.

A Priori and A Posteriori Error Estimates of Streamline Diffusion Finite Element Method for Optimal Control Problem Governed by Convection Dominated Diffusion Equation

In this paper,we investigate a streamline diffusion finite element approxi- mation scheme for the constrained optimal control problem governed by linear con- vection dominated diffusion equations.We prove the existence and uniqueness of the discretized scheme.Then a priori and a posteriori error estimates are derived for the state,the co-state and the control.Three numerical examples are presented to illustrate our theoretical results.

A FINITE ELEMENT METHOD FOR STRESS ANALYSIS OR ELASTOPLASTIC BODY WITH POLYGONAL LINE STRAIN——HARDENING

In this paper, the stress-strain curve of material is fitted by polygonal line composed of three lines. According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relations, which are given by the increment theory of elastoplasticity. Thus, the finite element equation with the solution of displacement is derived. The assemblage elastoplastic stiffness matrix can be obtained by adding something to the elastic matrix, hence it will shorten the computing time. The determination of every loading increment follows the von Mises yield criteria. The iterative method is used in computation. It omits the redecomposition of the assemblage stiffness matrix and it will step further to shorten the computing time. Illustrations are given to the high-order element application departure from proportional loading, the computation of unloading fitting to the curve and the problem of load estimation.

课程思政视角下校企合作课程“施工组织与管理”教学改革实践

为落实全国高校思想政治工作会议精神,响应“思政教育落实到每一节课”的号召,全面推进大思政课建设的工作;在课程思政视角下,以高职院校工程类专业群中“顶层互选”的校企合作课程“施工组织与管理”为例,从课程思政元素挖掘方法、课程思政元素渗入模式、解析思政元素融入专业课程案例等方面入手,对思政元素有效融入课程教学过程进行研究和实践,实现全员全程全方位育人,保证学生的专业知识学习与思政教育同步同向同行。

基于BIM技术的浅埋隧道无限元法数值研究

近年来,BIM技术在交通运输基础工程领域的应用日益广泛,如地铁、高铁、公路、隧道等项目全生命周期的管理都有BIM技术的参与。本研究通过BIM软件–Revit建立浅埋隧道的信息模型,基于BIM信息模型,导入ABAQUS有限元分析软件,对越秀公园站浅埋暗挖多孔隧道进行有限元与无限元耦合模拟,验证了无限元在隧道数值模拟中的可行性。其次通过设置不同的工况,验证了无限元与有限元耦合模拟的准确性,并且研究了隧道的开挖对不同工况下,地表沉降和衬砌内力的影响,得出最优的开挖工序,为后续浅埋隧道的力学行为的研究提供借鉴。

Three-axis magnetic flux leakage in-line inspection simulation based on finite-element analysis

With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage （MFL） in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.

基于不同围岩特性的隧洞衬砌厚度优化分析

基于不同围岩特性的隧洞衬砌厚度优化既能实现安全要求又可以降低工程投资。结合某电站引水隧洞,采用有限元分析法对隧洞在不同围岩特性下的受力情况进行数值模拟,计算分析在不同衬砌厚度下的应力、配筋及裂缝宽度情况,综合考虑安全性和经济性对结果进行分析比较,提出了针对不同围岩特性的隧洞衬砌厚度优化方案。研究结果表明,隧洞衬砌在运行期的应力情况是影响衬砌配筋的关键因素,不同围岩特性下衬砌厚度的选择应充分考虑隧洞衬砌应力、所需配筋及裂缝宽度因素影响,当衬砌达到一定厚度后,所需配筋及裂缝宽度趋于稳定。

基于离散元的重载铁路有砟轨道阻力特性研究

研究目的:有砟轨道在重载铁路中广泛采用,随着服役时间的增加,在列车荷载反复作用下,道床性能会随之变化,线路阻力呈现动态发展的时变特性。作为求解梁轨相互作用的关键,准确合理地选取线路纵向阻力是保证梁轨相互作用计算准确的前提,关系梁轨系统的正常使用与安全运营。研究结论:(1)颗粒级配由粗到细,纵向线阻力逐渐减小;摩擦系数由小到大,纵向线阻力稍微增加;(2)结合不同级配建立的道床模型模拟出的纵向线阻力-位移曲线,获得纵向线阻力动态演化模型,可知线路纵向阻力由新建线路的阻力29.7 kN/(m·线)演化到破碎充分时的23.6 kN/(m·线),退化幅度约为20.5%;(3)本研究成果可为开展全服役期内重载铁路的梁轨相互作用等相关研究提供关键参数。

抽油管的在线漏磁检测技术

由于复杂的工况,抽油管的内、外壁极易发生损伤。目前,抽油管的检测方式主要是将抽油管抽离油井后送至后线检测场地进行检测,造成了时间、人力、物力的浪费。采用漏磁检测方法,开展了抽油管在起管或下管过程中的在线检测;设计了瓦片式磁化结构,建立抽油管漏磁检测的三维仿真模型;针对抽油管的腐蚀缺陷,改变缺陷尺寸参数,研究了缺陷漏磁场的分布特性;研发了抽油管在线漏磁检测系统,在实验室和油田作业现场对抽油管进行在线检测试验。试验结果表明,该系统能够快速高效地完成抽油管的在线检测,为抽油管的损伤监测提供了一些参考。

基于振动台试验的鱼线固定梅瓶文物响应规律性研究

为了探索鱼线固定梅瓶文物在实际博物馆的地震响应以及抗震效果,首先选取了典型梅瓶文物,并在三层钢筋混凝土框架结构中开展了24种地震工况的振动台试验,然后建立了上述试验所用梅瓶文物的有限元模型,验证了有限元模型的准确性,最后采用增量动力分析法分析了该文物在两种常见直径鱼线保护措施下的运动响应。结果表明:鱼线固定梅瓶文物在地震作用下会产生滑移、摇摆、倾覆以及鱼线断裂等现象;不同楼层下的文物响应差别较大,尤其在大震作用下,高楼层的鱼线固定梅瓶文物易发生倾覆和鱼线断裂破坏,要重视高楼层文物的震前保护措施;在较强的地震作用下,仅依靠增大鱼线直径有时对控制文物的倾覆情况起不到关键性决定作用,需要进一步采取其它措施对文物进行保护。

颗粒阻尼器对输电塔线系统减震性能研究

对输电塔线系统进行缩尺模型振动台实验,从时域和频域的角度,对比了调谐质量阻尼器和颗粒阻尼器对输电塔的减震效果。利用ABAQUS建立了颗粒阻尼器控制输电塔线系统的离散元-有限元高精度耦合数值模型,对比了实验和模拟结果,并对塔线系统的耗能情况及颗粒阻尼器内部颗粒运动碰撞情况进行分析。研究结果表明:在地震激励下,颗粒阻尼器的减震效果较调谐质量阻尼器有更好的鲁棒性;该文所建立的颗粒阻尼器控制输电塔线系统模型能够良好地反映试件的动力特性和地震响应;在颗粒阻尼器的控制下,塔线系统总能量降低24.12%。当颗粒之间的碰撞次数和颗粒与容器的碰撞次数满足一定比例关系时,颗粒阻尼器能实现更优的控制效果。