现代机械工程(英文)最新文献_第7页

A Statistical Theory of the Damage of Materials 材料损伤的统计理论

现代机械工程(英文) Pub Date : 2016-11-11 DOI: 10.4236/MME.2016.64013

G. Zachariev

{"title":"A Statistical Theory of the Damage of Materials","authors":"G. Zachariev","doi":"10.4236/MME.2016.64013","DOIUrl":"https://doi.org/10.4236/MME.2016.64013","url":null,"abstract":"A statistical theory of disperse damage of materials gained under loading is proposed. It is based on the idea of distribution of potential damage spots within a specimen similar to the distribution of the strength values found by testing a set of identical specimens. A relation between damage risk and the probability of damage of a single specimen is assumed. It conforms to the relation between risk and probability of strength distribution of a set of identical specimens, according to Weibull’s statistical theory of material strength. The damage risk just like the damage probability are assumed to be functions of loading and time. Damage is modeled regarding two mechanisms—thermo-fluctuation damage based on the kinetic theory of material strength, and damage depending on a parameter called loading degree (percentage), which depends on load and time. The first mechanism adopts two relations regarding energy barrier reduction due to loading. Equations of damage advance under short-term loading (with a constant rate of load increase) and under long-term (constant) loading are derived. Theoretical relations of damage development are compared with experimental evidence gained via specific tests on short glass fibre reinforced polyoximethylene. The damage itself consists of the accumulation of additional internal surfaces within the entire material volume as measured by small angle scattering X-ray refractometry. It is shown that the mechanism of damage as a function of loading degree where time participates implicitly, gains advantage over the kinetic mechanism where time is explicitly present. The cumulative functions derived for damage accumulation can be used to assess not only damage, but also for statistical analysis of the strength and other quantities.","PeriodicalId":69007,"journal":{"name":"现代机械工程(英文)","volume":"06 1","pages":"129-150"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70497288","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}

引用次数: 4

Model Based Pressure Control of a Push Belt Continuously Variable Transmission 基于模型的推带无级变速器压力控制

现代机械工程(英文) Pub Date : 2016-11-11 DOI: 10.4236/MME.2016.64011

B. Alzuwayer, Aviral Singh, P. Muralidharan, Zhijun Han

引用次数: 3

Structural-Energy Characteristics of Tribotechnical Contact in Unsteady Operational Modes 非定常工作模式下摩擦接触的结构-能量特性

现代机械工程(英文) Pub Date : 2016-08-11 DOI: 10.4236/mme.2016.63010

T. Al-Quraan, O. O. Mikosyanchik, R. Mnatsakanov, Olexander I. Zаporozhets

{"title":"Structural-Energy Characteristics of Tribotechnical Contact in Unsteady Operational Modes","authors":"T. Al-Quraan, O. O. Mikosyanchik, R. Mnatsakanov, Olexander I. Zаporozhets","doi":"10.4236/mme.2016.63010","DOIUrl":"https://doi.org/10.4236/mme.2016.63010","url":null,"abstract":"The current tribological research is intended to achieve maximum wear resistance under the structural adaptability of tribocoupling elements, which requires application of means to reduce the activation of the metal surface layers, decrease in frictional work, regulation of passivation and temperature control. The aim of this study is to identify the patterns that influence the kinetics formation of the boundary layers of lubricating mineral gear oil on activated friction contact surfaces, and the increment of the friction specific work on wear-resistant steel 42Cr4 and 100Cr6 in frequent start and stop operation mode. Due to the activation of surface layers of metal in the non-stationary operating conditions of the contact surfaces, the gradual forming of the boundary lubricant adsorption layers with increased effective viscosity in contact occurs, exhibiting high adaptation ability, and the boundary layer thickness is from 0.2 to 4 microns. This research analyzed the lubricating ability of oil at the starting maximum torque of friction, showing that the thickness of the oil layer formed in contact had a dual nature—boundary and hydrodynamic. The pure rolling conditions promote localization of shear in the lubricating layers, and the high frictional properties of the transmission oil have been identified regardless of the hardness of the investigated surfaces.","PeriodicalId":69007,"journal":{"name":"现代机械工程(英文)","volume":"06 1","pages":"91-97"},"PeriodicalIF":0.0,"publicationDate":"2016-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70497219","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}

引用次数: 0

Ascending Series Analysis of the Transition Layer 过渡层的升级数分析

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2016.03.01.2

M. H. Hamdan, I. Gadoura, S. M. Alzahrani

引用次数: 3

Moisture Flow as Driving Force behind Drying Shrinkage and Microcracking in Interfacial Transition Zone in Concrete 混凝土界面过渡区干缩微裂的动力研究

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2015.02.02.3

Dragana Jankovic

引用次数: 0

Global College Rankings 全球大学排名

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2016.03.01.1

K. Wong

引用次数: 1

Design for the Lift Platform Humanoid Climb Assisting Unit of the Space Launch Site 航天发射场升降平台人形爬升辅助装置设计

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2015.02.02.2

Shan-zhen Yi

引用次数: 0

The SPH-EL Method for the Simulation of the Interaction between Water Drops and Solid Wall 水滴与固体壁面相互作用的SPH-EL模拟方法

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2015.02.02.4

L. Fang, F. Liu, S. Chen, J. Wu

引用次数: 0

Spatial Distribution of Material Properties in Load Bearing Femur as Characterized by Evolutionary Structural Optimization 基于演化结构优化的股骨承载材料性能空间分布研究

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2016.03.01.3

M. Bilgen, Lev Lafayette, H. Latifi

{"title":"Spatial Distribution of Material Properties in Load Bearing Femur as Characterized by Evolutionary Structural Optimization","authors":"M. Bilgen, Lev Lafayette, H. Latifi","doi":"10.15377/2409-9848.2016.03.01.3","DOIUrl":"https://doi.org/10.15377/2409-9848.2016.03.01.3","url":null,"abstract":"This works aims to simulate bone formation under natural loading using evolutionary structural optimization. Unlike material elimination by hard-kill approach applied previously, the current presentation implements material replacement defined as soft-kill method. A numerical analysis platform was developed and finite element model of sheep femur was constructed using computer tomography data. Quadruple material properties governing soft medullary canal, cancellous as well as plexiform and haversian cortical structures were considered as the main material constituents of the femur. An iterative algorithm was designed for determining the spatial distribution of these tissue types throughout the femur. The model initially started with a homogenous plexiform design and iteratively converged to a final state with heterogeneous density profile, nearly similar to a natural femur. The inefficient regions were gradually changed with mechanically lower grade and lighter tissues and thus the final construct had the least weight but still supported the load. The convergence was achieved successfully. . The tissue types were distributed in a mechanically optimum fashion to counteract the applied forces. The resulting internal material assignments provided insights into the structural remodeling of femur within the context of Wolff’s law. . Using the developments, bone formation can be simulated numerically under different mechanical loading conditions. Such investigations may provide useful information about the vulnerability of bone as its material properties change with osteoporosis or the fracture risk as a result of malfunction in muscles attached to the femur.","PeriodicalId":69007,"journal":{"name":"现代机械工程(英文)","volume":"3 1","pages":"17-24"},"PeriodicalIF":0.0,"publicationDate":"2016-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67286733","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}

引用次数: 0

Investigation of Displacements Fields Due to Normal and Tangential Loads on Bars of Finite Thickness 有限厚度杆在法向和切向荷载作用下的位移场研究

现代机械工程(英文) Pub Date : 2016-07-21 DOI: 10.15377/2409-9848.2015.02.02.1

B. Trentadue

引用次数: 0