This article deals with the analysis of equivalency of the substitution of rectangular stress block for nonlinear stress diagram with descending branch for the calculation of flexural, eccentrically compressed and eccentrically tensioned reinforced concrete members of rectangular cross-section. The method for equivalent substitution of these diagrams is proposed. Analytical relationships of area and its centre for the nonlinear diagram with descending branch are presented. Coefficients for equivalent substitution of the said diagrams for the standard concrete strength classes are determined and given. It gives the opportunity to design reinforced concrete members using rectangular stress block model. Substitution of the diagrams applied in EC2 and in STR 2.05.05:2005 is compared with the equivalent substitution of rectangular stress diagram for nonlinear stress diagram with descending branch. It is shown that in STR 2.05.05:2005 description of the ratio between the depth of the rectangular diagram and that of the equivalent nonlinear one with descending branch is very poor. An explicit analytical relationship for this ratio and its linear approximation in respect to the concrete characteristic and design strengths are presented in this article as well.
{"title":"Analysis of equivalent substitution of rectangular stress block for nonlinear stress diagram","authors":"E. Dulinskas, D. Zabulionis","doi":"10.5755/j02.mech.36222","DOIUrl":"https://doi.org/10.5755/j02.mech.36222","url":null,"abstract":"This article deals with the analysis of equivalency of the substitution of rectangular stress block for nonlinear stress diagram with descending branch for the calculation of flexural, eccentrically compressed and eccentrically tensioned reinforced concrete members of rectangular cross-section. The method for equivalent substitution of these diagrams is proposed. Analytical relationships of area and its centre for the nonlinear diagram with descending branch are presented. Coefficients for equivalent substitution of the said diagrams for the standard concrete strength classes are determined and given. It gives the opportunity to design reinforced concrete members using rectangular stress block model. Substitution of the diagrams applied in EC2 and in STR 2.05.05:2005 is compared with the equivalent substitution of rectangular stress diagram for nonlinear stress diagram with descending branch. It is shown that in STR 2.05.05:2005 description of the ratio between the depth of the rectangular diagram and that of the equivalent nonlinear one with descending branch is very poor. An explicit analytical relationship for this ratio and its linear approximation in respect to the concrete characteristic and design strengths are presented in this article as well.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"32 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140743204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dependence of the hardened layer depth on the modes of superficial treatment is experimentally investigated, with the purpose of evaluation of known laws of initial linear contact of the strengthening part and the tool. The method of the definition of optimum loading on strengthening tool (the steel cylindrical roller) and its radius at static stamping is offered. The technique is examined with the reference to the case parts made of aluminum alloys.
{"title":"Features of hardening of the case parts made of aluminium alloys","authors":"M. Matlin, S. Lebsky, A. Frolova, A. Mozgunova","doi":"10.5755/j02.mech.36221","DOIUrl":"https://doi.org/10.5755/j02.mech.36221","url":null,"abstract":"The dependence of the hardened layer depth on the modes of superficial treatment is experimentally investigated, with the purpose of evaluation of known laws of initial linear contact of the strengthening part and the tool. The method of the definition of optimum loading on strengthening tool (the steel cylindrical roller) and its radius at static stamping is offered. The technique is examined with the reference to the case parts made of aluminum alloys.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"25 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140743032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Results of researches on strength and stiffness of diagonally bending sandwich girders having geometric and/or stiffness asymmetry have been given. A mathematical module for calculation of normal strain (strength) and stiffness on bending at any cross-section point of sandwich girder has been proposed. The kinetics of stiffness on bending and strength variation dependences when geometric parameters of a cross-section and tension modulus ratios of girder layers are changing have been examined. It has been established that the strength of a diagonally bending sandwich girder on the whole depends on the position of the centre of stiffness and the position of the neutral plane.
{"title":"Stress distribution in multilayer structural element subjected to skew bending","authors":"J. Bareišis, A. Daniškevičiūtė, V. Kleiza","doi":"10.5755/j02.mech.36220","DOIUrl":"https://doi.org/10.5755/j02.mech.36220","url":null,"abstract":"Results of researches on strength and stiffness of diagonally bending sandwich girders having geometric and/or stiffness asymmetry have been given. A mathematical module for calculation of normal strain (strength) and stiffness on bending at any cross-section point of sandwich girder has been proposed. The kinetics of stiffness on bending and strength variation dependences when geometric parameters of a cross-section and tension modulus ratios of girder layers are changing have been examined. It has been established that the strength of a diagonally bending sandwich girder on the whole depends on the position of the centre of stiffness and the position of the neutral plane.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"13 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140743966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The possibilities to use a miniaturized robotic system for inspection, exploration and maintenance of the pipes are highlighted. In this paper, the authors’ contributionin this field is discussed. Two in-pipe minirobots developed by the authors are described. The efforts are focused on the in-pipe mobility and corresponding actuationsystems. Several functional characteristics (e.g. the maximum /minimum inner pipe diameter) are given.
{"title":"Development of mobile minirobots for in pipe inspection tasks","authors":"O. Tǎtar, D. Mandru, I. Ardelean","doi":"10.5755/j02.mech.36228","DOIUrl":"https://doi.org/10.5755/j02.mech.36228","url":null,"abstract":"The possibilities to use a miniaturized robotic system for inspection, exploration and maintenance of the pipes are highlighted. In this paper, the authors’ contributionin this field is discussed. Two in-pipe minirobots developed by the authors are described. The efforts are focused on the in-pipe mobility and corresponding actuationsystems. Several functional characteristics (e.g. the maximum /minimum inner pipe diameter) are given.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"3 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140742529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study the influence of environment temperature on the mechanical properties (tensile strength and elasticity modulus at break) of laminated leather and its layers (split leather and microporous polyurethane (PU) Permair film) under fatigue flexing have been investigated. The testing was carried out by changing the temperature from 20 ± 2°C to −20 ± 2°C (number of cycles NC = 105). The experimental results showed that the character of the dependences of tensile strength and elasticity modulus at break on temperature of fatigue environment of both leathers is similar and significantly differ from characters of analogous dependences of microporous PU film. The defects on the surface of laminated leather become clearly visible when the temperature falls to ≤ -10°C.
{"title":"Effect of environment temperature on fatigue properties of laminated leather","authors":"D. Milašienė","doi":"10.5755/j02.mech.36224","DOIUrl":"https://doi.org/10.5755/j02.mech.36224","url":null,"abstract":"In this study the influence of environment temperature on the mechanical properties (tensile strength and elasticity modulus at break) of laminated leather and its layers (split leather and microporous polyurethane (PU) Permair film) under fatigue flexing have been investigated. The testing was carried out by changing the temperature from 20 ± 2°C to −20 ± 2°C (number of cycles NC = 105). The experimental results showed that the character of the dependences of tensile strength and elasticity modulus at break on temperature of fatigue environment of both leathers is similar and significantly differ from characters of analogous dependences of microporous PU film. The defects on the surface of laminated leather become clearly visible when the temperature falls to ≤ -10°C.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140742708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most current lower arm/hand prosthesis designs incorporate relatively bulky, heavy dc motors that produce substantial noise when performing actuation which rendersthem uncomfortable for the end-user. The engineering challenge is to produce more effective powered upper limb prosthetic solutions. Identification, characterisation and testing of actuation methods with better force to weight ratios are essential pre-requisites for this. The main aim of this work is to carry out a comprehensive study to establish conclusively the feasibility of employing Shape Memory Alloys (SMA’s) in the actuation of prosthetic finger designs. A comprehensive review of existing literature has been undertaken in order to establish the maximum grip forces at each phalanx of the human hand under different loading conditions. An experiment was developed in conjunction with this review to estimate the time response of the hand during a gripping/releasing action. These results, in combination with physical dimensions, will be used to drive the design of a prosthetic limb. A test rig has been developed which can facilitate complete transient and steady-state characterisation of a range of SMA wire diameters and bundle configurations. Anumber of different configurations were tested, each configuration having a different combination of 150 μm and 300 μm diameter nitinol wires. A data acquisition systemwas used to capture and retain data pertaining to the full characterisation of the bundles and in particular the strain and force capabilities of the various arrangements. A direct comparison is made between the actuator capabilities and the requirements of a working limb for basic gripping actions. This work will contribute to the development of an improved powered prosthetic solution.
目前大多数下肢/手部假肢设计都采用了相对笨重的直流电机，这些电机在执行驱动时会产生巨大噪音，使最终用户感到不适。工程设计面临的挑战是生产出更有效的上肢假肢解决方案。为此，必须对具有更好力重比的驱动方法进行鉴定、表征和测试。这项工作的主要目的是开展一项综合研究，以最终确定在假肢手指设计的驱动中采用形状记忆合金（SMA）的可行性。我们对现有文献进行了全面审查，以确定在不同加载条件下人手每个指骨的最大握力。在进行综述的同时，我们还开发了一项实验，以估算手部在抓取/释放动作中的时间响应。这些结果与物理尺寸相结合，将用于推动假肢的设计。我们开发了一套测试装置，可以对一系列 SMA 线径和线束配置进行完整的瞬态和稳态表征。测试了多种不同的配置，每种配置都有不同的直径为 150 μm 和 300 μm 的镍钛诺丝组合。数据采集系统用于捕获和保留与线束全面特性有关的数据，特别是各种排列的应变和受力能力。对致动器的能力和工作肢体对基本抓取动作的要求进行了直接比较。这项工作将有助于改进动力假肢解决方案的开发。
{"title":"Transient characterisation and analysis of shape memory alloy wire bundles for the actuation of finger joints in prosthesis design","authors":"K. O'Toole, M. McGrath, D. Hatchett","doi":"10.5755/j02.mech.36229","DOIUrl":"https://doi.org/10.5755/j02.mech.36229","url":null,"abstract":"Most current lower arm/hand prosthesis designs incorporate relatively bulky, heavy dc motors that produce substantial noise when performing actuation which rendersthem uncomfortable for the end-user. The engineering challenge is to produce more effective powered upper limb prosthetic solutions. Identification, characterisation and testing of actuation methods with better force to weight ratios are essential pre-requisites for this. The main aim of this work is to carry out a comprehensive study to establish conclusively the feasibility of employing Shape Memory Alloys (SMA’s) in the actuation of prosthetic finger designs. A comprehensive review of existing literature has been undertaken in order to establish the maximum grip forces at each phalanx of the human hand under different loading conditions. An experiment was developed in conjunction with this review to estimate the time response of the hand during a gripping/releasing action. These results, in combination with physical dimensions, will be used to drive the design of a prosthetic limb. \u0000A test rig has been developed which can facilitate complete transient and steady-state characterisation of a range of SMA wire diameters and bundle configurations. Anumber of different configurations were tested, each configuration having a different combination of 150 μm and 300 μm diameter nitinol wires. A data acquisition systemwas used to capture and retain data pertaining to the full characterisation of the bundles and in particular the strain and force capabilities of the various arrangements. A direct comparison is made between the actuator capabilities and the requirements of a working limb for basic gripping actions. This work will contribute to the development of an improved powered prosthetic solution.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"49 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140742977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The normal contact of the elastic spherical particle with deformable boundary is investigated in terms of the Discrete Element Method (DEM). The particle of the prescribed radius is moving under gravity and the initial velocity. The deformable boundary is treated as rigidly fixed spherical particle with variable elasticity modulus and variable radius. The limit case, approaching the infinite radius presents an elastic half-space, while increasing of the elasticity modulus presents the rigid boundary, respectively. The linear model and the nonlinear Hertz contact model used in the discrete element method are investigated numerically by applying the 5th-order Gear’s predictorcorrector integration scheme. The numerical model is tested by comparing it with analytical solution. The time variations of the particle positions, velocities and accelerations are presented. On the basis of simulation results the limit values of the boundary particle parameters are evaluated and recommendations for the boundary article parameters required in DEM simulation are drown.
本文采用离散元法（DEM）研究了具有可变形边界的弹性球形粒子的法向接触问题。规定半径的粒子在重力和初速度作用下运动。可变形边界被视为具有可变弹性模量和可变半径的刚性固定球形质点。在接近无限半径的极限情况下，会出现弹性半空间，而弹性模量增大则会出现刚性边界。离散元方法中使用的线性模型和非线性赫兹接触模型是通过五阶 Gear's predictorcorctor 积分方案进行数值研究的。通过与分析解进行比较，对数值模型进行了测试。文中给出了粒子位置、速度和加速度的时间变化。在模拟结果的基础上，对边界粒子参数的极限值进行了评估，并对 DEM 模拟中所需的边界条件参数提出了建议。
{"title":"Modelling deformable boundary by spherical particle for normal contact","authors":"R. Jasevičius, R. Kačianauskas","doi":"10.5755/j02.mech.36219","DOIUrl":"https://doi.org/10.5755/j02.mech.36219","url":null,"abstract":"The normal contact of the elastic spherical particle with deformable boundary is investigated in terms of the Discrete Element Method (DEM). The particle of the prescribed radius is moving under gravity and the initial velocity. The deformable boundary is treated as rigidly fixed spherical particle with variable elasticity modulus and variable radius. The limit case, approaching the infinite radius presents an elastic half-space, while increasing of the elasticity modulus presents the rigid boundary, respectively. \u0000The linear model and the nonlinear Hertz contact model used in the discrete element method are investigated numerically by applying the 5th-order Gear’s predictorcorrector integration scheme. The numerical model is tested by comparing it with analytical solution. The time variations of the particle positions, velocities and accelerations are presented. On the basis of simulation results the limit values of the boundary particle parameters are evaluated and recommendations for the boundary article parameters required in DEM simulation are drown.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"5 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140741285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a low-cost hardware platform for outdoor robots, being suitable for education, industrial prototyping and private use. The choice of components isdiscussed, including platform, sensors and controller as well as GPS and image processing hardware. Furthermore, a software approach is proposed, allowing students and researchers to easily implement own algorithms for localization, navigation and the tasks to fulfill. Several robots can be integrated in a framework which connects various different hardware platforms, called the BOSPORUS network. Together with other components, they form an intelligent network for gathering sensor and image data, sensor data fusion, navigation and control of mobile platforms. The architecture of a reference platform on the campus of the Brandenburg University of Applied Sciences is presented and evaluated.
{"title":"Autonomous mobile robots for outdoor tasks","authors":"H. Loose","doi":"10.5755/j02.mech.36230","DOIUrl":"https://doi.org/10.5755/j02.mech.36230","url":null,"abstract":"This paper presents a low-cost hardware platform for outdoor robots, being suitable for education, industrial prototyping and private use. The choice of components isdiscussed, including platform, sensors and controller as well as GPS and image processing hardware. Furthermore, a software approach is proposed, allowing students and researchers to easily implement own algorithms for localization, navigation and the tasks to fulfill. Several robots can be integrated in a framework which connects various different hardware platforms, called the BOSPORUS network. Together with other components, they form an intelligent network for gathering sensor and image data, sensor data fusion, navigation and control of mobile platforms. The architecture of a reference platform on the campus of the Brandenburg University of Applied Sciences is presented and evaluated.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"18 24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140744674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The reactions of pipeline systems to shock impact load and the possibilities of the simulation and evaluation of dynamic processes are investigated in the paper. A heterogeneous system is composed of the elements with different properties, e.g. a pipeline with the sediment inside. Impact effect on it is one of the most effective methods to make substantial qualitative and quantitative changes in such system. The mathematical model for calculation of the elastically plastic displacements of the sediment was derived. It allows the analysis of dynamics of the change of the system’s specific state. The paper presents the calculation results of elastically plastic displacements of the substance caused by explosions in pipeline systems.
{"title":"Analysis the interaction of two cylindrical surfaces under shock impact load","authors":"V. Doroševas, Vitalijus Volkovas","doi":"10.5755/j02.mech.36226","DOIUrl":"https://doi.org/10.5755/j02.mech.36226","url":null,"abstract":"The reactions of pipeline systems to shock impact load and the possibilities of the simulation and evaluation of dynamic processes are investigated in the paper. A heterogeneous system is composed of the elements with different properties, e.g. a pipeline with the sediment inside. Impact effect on it is one of the most effective methods to make substantial qualitative and quantitative changes in such system. The mathematical model for calculation of the elastically plastic displacements of the sediment was derived. It allows the analysis of dynamics of the change of the system’s specific state. The paper presents the calculation results of elastically plastic displacements of the substance caused by explosions in pipeline systems.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"7 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140745055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Present paper describes the comparison of two different material properties identification techniques in order to investigate a possibility of combination of two techniques into one powerful and fast tool for material properties identification. Both methods are theoretically described and main options are given in this article. Some experiments wherein aluminium material properties are identified are carried out. Methods are qualified, conclusions and proposals are given.
{"title":"Material properties identification. Comparison of two techniques","authors":"P. Ragauskas, E. Skukis","doi":"10.5755/j02.mech.36223","DOIUrl":"https://doi.org/10.5755/j02.mech.36223","url":null,"abstract":"Present paper describes the comparison of two different material properties identification techniques in order to investigate a possibility of combination of two techniques into one powerful and fast tool for material properties identification. Both methods are theoretically described and main options are given in this article. Some experiments wherein aluminium material properties are identified are carried out. Methods are qualified, conclusions and proposals are given.","PeriodicalId":511970,"journal":{"name":"Mechanics","volume":"39 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140743121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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