3-RPS并联机器人静力学研究及SimMechanics仿真

针对传统的建模方法忽略连杆自身重力并具有较大误差这一问题,对单个杆件在铰链约束及重力作用下的受力情况进行分析,推导出机器人处于任意位姿时连杆受力与动平台负载力(矩)二者的关系,从而建立了3-RPS并联机器人完整的静力学模型.利用Matlab的SimMechanics和Simulink模块库构造出该3-RPS并联机器人的仿真模型,对该模型进行受力仿真,验证了静力学模型的正确性.该研究同样适用于其他种类的3自由度并联机器人.

基于Solidworks创建的机械手的SimMechanics仿真

通过Solidworks为三维建模软件,快速建立了三指机械手三维实体模型。阐述CAD模型建立后,导入Sim Mechanics仿真的方法。通过机械手在Sim Mechanics中的仿真,得到其仿真动画,研究其运动学特性。仿真流程的建立将为后续轨迹优化算法设计、动力学分析研究,提供仿真和验证途径。

Editorial for Multiscale&Multifield Coupling in Geomechanics

We are delighted to serve as guest editors for this special issue in the Journal of Rock Mechanics and Geotechnical Engineering.The purpose of this special issue is dedicated to gathering the latest research work on Multiscale&Multifield Coupling in Geomechanics,where we delve into the intricate interplay of various fields and scales that govern the behavior of geomaterials.In total,30 manuscripts from USA,China,UK,Germany,Canada,India and United Arab Emirates are selected to be included in this issue.

Induction System for a Fusion Reactor: Quantum Mechanics Chained up

In the quest for a sustainable and abundant energy source, nuclear fusion technology stands as a beacon of hope. This study introduces a groundbreaking quantum mechanically effective induction system designed for magnetic plasma confinement within fusion reactors. The pursuit of clean energy, essential to combat climate change, hinges on the ability to harness nuclear fusion efficiently. Traditional approaches have faced challenges in plasma stability and energy efficiency. The novel induction system presented here not only addresses these issues but also transforms fusion reactors into integrated construction systems. This innovation promises compact fusion reactors, marking a significant step toward a clean and limitless energy future, free from the constraints of traditional power sources. This revolutionary quantum induction system redefines plasma confinement in fusion reactors, unlocking clean, compact, and efficient energy production.

Case study on the mechanics of NPR anchor cable compensation for large deformation tunnel in soft rock in the Transverse Mountain area,China

A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.

Characteristics of Rock Mechanics Response and Energy Evolution Regime of Deep Reservoirs in the Bozhong Sag,Bohai Bay Basin

Hydraulic fracturing is a mature and effectivemethod for deep oil and gas production,which provides a foundation for deep oil and gas production.One of the key aspects of implementing hydraulic fracturing technology lies in understanding mechanics response characteristics of rocks in deep reservoirs under complex stress conditions.In this work,based on outcrop core samples,high-stress triaxial compression tests were designed to simulate the rock mechanics behavior of deep reservoirs in Bozhong Sag.Additionally,this study analyzes the deformation and damage law for rock under different stress conditions.Wherein,with a particular focus on combining energy dissipation theory to further understand damage law for deep reservoirs.The experimental results show that regardless of stress conditions,the process of deformation/failure of deep-seated reservoirs goes through five stages:Fracture compaction,newfracture formation,stable fracture expansion,unstable fracture expansion,and post-peak residual deformation.Under different stress conditions,the energy change laws of specimens are similar.The energy dissipation process of rocks corresponds closely to the trend of deformation-failure curve,then displays distinctive stage characteristics.Wherein,in stage of rock fracture compaction,the input energy curve is approximately coincident with the elastic strain energy curve,while the dissipation energy curve remains near zero.With the increase of strain,the growth rate of elastic strain energy increases gradually,but with the deformation entering the crack propagation stage,the growth rate of elastic strain energy slows down and the dissipation energy increases gradually.Finally,in the post-peak stage,rock fracture releases a lot of energy,which leads to the sharp decline of elastic strain energy curve.In addition,the introduction of damage variable D quantifies the analysis of the extent of failure for rocks.During the process of increasing strain,rock damage exhibits nonlinear growth with increasing stress.

Dental Treatment Using Quantum Mechanics for Knee Joint Pain

In clinical practice, dentists sometimes encounter phenomena that cannot be explained by modern western medical concepts;for example, the patient’s medical symptoms improve by bringing medicines or dentures close to the body. Although it seems difficult to completely elucidate the mechanism through modern western medicine, it can be explained using quantum mechanics. The quantum, the smallest unit of matter composition, exhibits wave-particle duality. The fact that symptoms can be improved simply by bringing dentures or medicines closer to the body indicates that the waves emitted by dentures or medicines interfere with the pathological waves emitted by the pathological site. Thus, the pathological waves are deformed and lead to a change in symptoms. In this way, quantum theory can explain phenomena that are difficult to elucidate in conventional medicine, which are encountered in clinical practice. So far, the author has presented a case of difficulty in raising the upper limb where the symptoms improved without the need for dentures in the mouth by adjusting the dentures outside the mouth. This time, the author would like to introduce a case which the patient’s knee pain improved by adjusting the dentures outside the mouth.

New Approach to Synchronize General Relativity and Quantum Mechanics with Constant “K”-Resulting Dark Matter as a New Fundamental Force Particle

Planck scale plays a vital role in describing fundamental forces. Space time describes strength of fundamental force. In this paper, Einstein’s general relativity equation has been described in terms of contraction and expansion forces of space time. According to this, the space time with Planck diameter is a flat space time. This is the only diameter of space time that can be used as signal transformation in special relativity. This space time diameter defines the fundamental force which belongs to that space time. In quantum mechanics, this space time diameter is only the quantum of space which belongs to that particular fundamental force. Einstein’s general relativity equation and Planck parameters of quantum mechanics have been written in terms of equations containing a constant “K”, thus found a new equation for transformation of general relativity space time in to quantum space time. In this process of synchronization, there is a possibility of a new fundamental force between electromagnetic and gravitational forces with Planck length as its space time diameter. It is proposed that dark matter is that fundamental force carrying particle. By grand unification equation with space-time diameter, we found a coupling constant as per standard model “αs” for that fundamental force is 1.08 × 10-23. Its energy calculated as 113 MeV. A group of experimental scientists reported the energy of dark matter particle as 17 MeV. Thorough review may advance science further.

An 8-Node Plane Hybrid Element for StructuralMechanics Problems Based on the Hellinger-Reissner Variational Principle

The finite element method (FEM) plays a valuable role in computer modeling and is beneficial to the mechanicaldesign of various structural parts. However, the elements produced by conventional FEM are easily inaccurate andunstable when applied. Therefore, developing new elements within the framework of the generalized variationalprinciple is of great significance. In this paper, an 8-node plane hybrid finite element with 15 parameters (PHQ8-15β) is developed for structural mechanics problems based on the Hellinger-Reissner variational principle.According to the design principle of Pian, 15 unknown parameters are adopted in the selection of stress modes toavoid the zero energy modes.Meanwhile, the stress functions within each element satisfy both the equilibrium andthe compatibility relations of plane stress problems. Subsequently, numerical examples are presented to illustrate theeffectiveness and robustness of the proposed finite element. Numerical results show that various common lockingbehaviors of plane elements can be overcome. The PH-Q8-15β element has excellent performance in all benchmarkproblems, especially for structures with varying cross sections. Furthermore, in bending problems, the reasonablemesh shape of the new element for curved edge structures is analyzed in detail, which can be a useful means toimprove numerical accuracy.

Improved Units of Measure in Rotational Mechanics

The SI system of units in rotational mechanics yields correct numerical results, but it produces physically incorrect units of measure in many cases. SI units also violate the principle of general covariance—the general rule for defining continuous coordinates and units in mathematics and mathematical physics. After 30+ years of wrestling with these problems, the ultimate authority on units of measure has declared that Newton–meter and Joule are not equivalent in rotational mechanics, as they are in the rest of physics. This article proposes a simple modification to SI units called “Nonstandard International units” (“NI units”) until a better name is agreed upon. NI units yield correct numerical results and physically correct units of measure, and they satisfy the principle of general covariance. The main obstacle to the adoption of NI units is the consensus among users that the radius of rotation should have the unit meter because the radius can be measured with a ruler. NI units assigned to radius should have units meter/radian because the radius is a conversion factor between angular size and circumferential length, as in arclength = rθ. To manage the social consensus behind SI units, the author recommends retaining SI units as they are, and informing users who want correct units that NI units solve the technical problems of SI units.

Investigation of the Micro-Mechanics of an Extruded Precipitation-Strengthened Magnesium Alloy under Cyclic Loading

Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macroscopic mechanical response of magnesium alloys under cyclic loading conditions, we employed a crystal plasticity model to analyze the stress-strain curves, specific crystal plane diffraction intensities, and the temporal evolution of various microscopic deformation mechanisms and twinning volume fractions for an extruded magnesium alloy, AXM10304, containing coherent precipitates. The research findings indicate that precipitation does not fundamentally alter the microscopic mechanisms of this alloy. However, it hinders twinning during the compression stage, mildly promotes detwinning during the tension stage, and enhances tension secondary hardening by elevating the difficulty of activation of the prismatic slip.

Teaching Experiment in Engineering Mechanics Based on Simulation Technology:A Case Study

This paper explores the integration of simulation technology in Engineering Mechanics(EM)teaching in vocational colleges.A case study was conducted using the tensile test as an example,and digital resources,such as colored Mises stress nephograms,were obtained.These resources were integrated into the original curriculum to conduct teaching experiments.The results show that the use of digital resources significantly improved the quality of teaching in EM.The integration of simulation technology in EM teaching provides a promising direction for the improvement of vocational education and the cultivation of high-quality skilled talents.The development and application of more simulation-based teaching cases should be studied by scholars.

Research on the Assessment System of Computational Mechanics Courses Based on the TOPSIS Entropy Weight Model

This paper takes the assessment and evaluation of computational mechanics course as the background,and constructs a diversified course evaluation system that is student-centered and integrates both quantitative and qualitative evaluation methods.The system not only pays attention to students’practical operation and theoretical knowledge mastery but also puts special emphasis on the cultivation of students’innovative abilities.In order to realize a comprehensive and objective evaluation,the assessment and evaluation method of the entropy weight model combining TOPSIS(Technique for Order Preference by Similarity to Ideal Solution)multi-attribute decision analysis and entropy weight theory is adopted,and its validity and practicability are verified through example analysis.This method can not only comprehensively and objectively evaluate students’learning outcomes,but also provide a scientific decision-making basis for curriculum teaching reform.The implementation of this diversified course evaluation system can better reflect the comprehensive ability of students and promote the continuous improvement of teaching quality.

基于SimMechanics的三自由度并联打磨机构动力学分析与仿真

针对一种新型三自由度并联打磨机构进行了运动学和动力学分析,并借助于MatLab/SimMechanics工具箱的系统动态建模功能,搭建了一精确的仿真平台。结果表明:当并联打磨机构末端受广义力矢量作用时,在仿真平台上对系统进行Lagrange方法的动力学仿真分析,示波器跟踪动平台中心点的位置、速度及加速度,从而获得驱动关节力和动平台位姿的函数曲线关系,可验证所设计机构的动力学特性是否理想。

基于Creo及SimMechanics对3-TPT并联机构的运动学仿真与模拟

针对一种3-TPT并联机构进行运动学模拟仿真,利用Creo 2.0建立了虚拟样机模型,并推导出了并联机构的运动学正、逆解方程。借助于Matlab中SimMechanics模块的系统动态建模功能,创建了3-TPT并联机构运动模型;利用Simulink和模糊控制箱建立了模糊PID控制器,将其与SimMechanics模型连接,对3-TPT并联机构进行动态仿真模拟,得出伸缩杆位速度变化曲线;通过对曲线的分析研究,可以得出该并联机构的运动平稳性较好。该方法能够直观地对并联机构进行可视化运动分析,进而可为3-TPT并联机构的结构参数优化、性能分析及模糊PID控制器的设计提供参考依据。

基于Matlab-Sim Mechanics的机电产品组成建模与仿真技术研究

分析了目前几种产品建模方法的特点。比较了机电一体化产品组成的现有划分方法。针对以广义执行机构为主功能的机电一体化产品组成划分 ,提出了结合Matlab软件的SimMechanics工具箱建立机电一体化产品的广义执行机构模型、传感器模型和控制策略模型的机电产品组成对象建模的方法 ,为机电一体化产品方案生成后的进一步仿真分析奠定了基础。文章以特定的机电一体化产品———家用多功能缝纫机的横针机构子系统为例 ,阐明了这种建模方法和仿真技术的具体应用 。

基于SimMechanics的单摆机构运动分析与仿真

采用Sim Mechanics模块建立了单摆系统的仿真模型,提出运用Sim Mechanics模块对单摆系统进行运动分析的方法,检测单摆系统的运动曲线。仿真表明:利用Sim Mechanics模块对单摆机构进行建模,所获曲线平滑无冲击,且建模过程方便简单,仿真直观,数据可靠,为其他复杂的机械结构提供一种仿真手段。

基于SimMechanics的平面四杆机构运动分析与仿真

简要介绍了 Sim Mechanics动态仿真工具 ,提出了运用仿真技术对平面四杆机构进行运动分析的方法。通过实例得出 :它具有系统建模方便直观 ,仿真功能强大 ,自动模型分析等强大优势 ,可很好地对机械系统的各种运动进行分析 ,从而可为机械系统的建模仿真提供一个强大而方便的工具。

基于ProE的联合收割机二级齿轮减速器仿真分析

针对联合收割机二级齿轮减速器总体结构进行了设计,基于Pro/E建立了二级齿轮减速器模型并完成了产品的装配,最后利用Pro/E Mechanism仿真模块对所设计产品进行了运动仿真。结果表明:模型满足设计需求,具有较好的稳定性,对二级齿轮减速器进一步的优化设计具有一定参考作用。

基于SimMechanics的经编机平面十杆机构运动学建模及仿真研究

运用SimMechanics建立了经编机传动舌针的仿真模型,并对其进行了运动学仿真,得到了该重要机构中某一关键点的瞬时位置、速度和加速度仿真曲线.仿真结果表明:该方法对机械系统进行建模分析,具有便捷高效、功能强大等优点,为复杂多杆机构的设计分析提供了一定的理论依据和较好的仿真分析方法.