Time-dependent reliability and optimal design of scraper chains based on fretting wear process

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shuai Li ◽  
Zhencai Zhu ◽  
Hao Lu ◽  
Gang Shen
Keyword(s):  
Optimal Design ◽  
Physical Model ◽  
Fretting Wear ◽  
Time Dependent ◽  
Dynamic Tension ◽  
Content Type ◽  
Dynamic Reliability ◽  
Wear Process ◽  
Scraper Conveyor ◽  
Wear Modes

Purpose This paper aims to present a dynamic reliability model of scraper chains based on the fretting wear process and propose a reasonable structural optimization method. Design/methodology/approach First, the dynamic tension of the scraper chain is modeled by considering the polygon effect of the scraper conveyor. Then, the numerical wear model of the scraper chain is established based on the tangential and radial fretting wear modes. The scraper chain wear process is introduced based on the diameter wear rate. Furthermore, the time-dependent reliability of scraper chains based on the fretting wear process is addressed by the third-moment saddlepoint approximation (TMSA) method. Finally, the scraper chain is optimized based on the reliability optimization design theory. Findings There is a correlation between the wear and the dynamic tension of the scraper conveyor. The unit sliding distance of fretting wear is affected by the dynamic tension of the scraper conveyor. The reliability estimation of the scraper chain with incomplete probability information is achieved by using the TMSA for the method needs only the first three statistical moments of the state variable. From the perspective of the chain drive system, the reliability-based optimal design of the scraper chain can effectively extend its service life and reduce its linear density. Originality/value The innovation of the work is that the physical model of the scraper chain wear is established based on the dynamic analysis of the scraper conveyor. And based on the physical model of wear, the time-dependent reliability and optimal design of scraper chains are carried out.

Effects of attapulgite on the worn surface and fretting wear resistance property of UHMWPE composites

2020 ◽  
Vol 72 (7) ◽  
pp. 821-827
Author(s):  
Zhaojie Meng ◽  
Yunxia Wang ◽  
Xiaocui Xin ◽  
Hao Liu ◽  
Yunfeng Yan ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Peer Review ◽  
Filler Content ◽  
Resistance Mechanism ◽  
Three Dimensional ◽  
Fretting Wear ◽  
Wear Property ◽  
Pressing Method ◽  
Content Type ◽  
Worn Surface

Purpose The purpose of this study is to examine the fretting wear property of ultra-high molecular weight polyethylene (UHMWPE)-based composites reinforced by different content of attapulgite. Design/methodology/approach A series of composites were prepared by a hot-pressing method. Fretting tests were carried out using an SRV-IV oscillating reciprocating friction wear tester with a load of 10 N and a frequency of 100 Hz. The morphology of the fracture structure and the worn surface was observed by field-emission scanning electron microscopy, X-ray diffraction and a non-contact three dimensional surface profiler. Findings With the addition of attapulgite, the microstructure of the composites become more regular, and their heat resistance improved. Furthermore, the friction coefficient and the specific wear rate of the composites with lower filler content reduced compared with that of neat UHMWPE, and the optimum filler content is 1 per cent. Originality/value The study investigated the fretting resistance mechanism of the attapulgite in the UHMWPE matrix. The results could help to provide some experimental evidence for the broader application of silicates on the fretting wear resistance of polymers. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0420/

A parallel partition of unity method for the unsteady Stokes equations

2017 ◽  
Vol 27 (9) ◽  
pp. 2105-2114
Author(s):  
Xiaoying Zhao ◽  
Yanren Hou ◽  
Guangzhi Du
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stokes Equations ◽  
Partition Of Unity ◽  
Time Dependent ◽  
The Finite Element Method ◽  
Partition Of Unity Method ◽  
Content Type ◽  
Standard Galerkin Method ◽  
Unsteady Stokes Equations

Purpose The purpose of this paper is to propose a parallel partition of unity method to solve the time-dependent Stokes problems. Design/methodology/approach This paper solved the time-dependent Stokes equations using the finite element method and the partition of unity method. Findings The proposed method in this paper obtained the same accuracy as the standard Galerkin method, but it, in general, saves time. Originality/value Based on a combination of the partition of unity method and the finite element method, the authors, in this paper, propose a new parallel partition of unity method to solve the unsteady Stokes equations. The idea is that, at each time step, one need to only solve a series of independent local sub-problems in parallel instead of one global problem. Numerical tests show that the proposed method not only reaches the same convergence orders as the fully discrete standard Galerkin method but also saves ample computing time.

Experimental Study on Tool Wear when Machining Super Titanium Alloys: Ti6Al4V and Ti-555

2013 ◽  
Vol 763 ◽  
pp. 51-64
Author(s):  
Mohammed Nouari ◽  
Hamid Makich
Keyword(s):  
Tool Wear ◽  
Temperature Rise ◽  
Wear Behavior ◽  
Flow Direction ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Cutting Conditions ◽  
Wear Process ◽  
Texture Modification ◽  
Wear Modes

To understand the effect of the workpiece microstructure on the tool wear behavior, anexperimental investigation was conducted on machining two different microstructures of supertitanium alloys: Ti-6Al-4V and Ti-555. The analysis of tool-chip interface parameters such asfriction, heat flux and temperature rise and the evolution of the workpiece microstructure underdifferent cutting conditions have been discussed. As cutting speed and feed rate increase, the meancutting forces and temperature show different progressions depending on the consideredmicrostructure. Results show that wear modes for cutting tools used in machining the Ti-555 alloyshow contrast from those exhibited by tools used in machining the Ti6AI4V alloy. In fact, onlyabrasion wear was observed for cutting tools in the case of machining the near-β titanium Ti-555alloy. The last alloy is characterized by a fine-sized microstructure (order of 1 μm). For the usualTi6Al4V alloy, adhesion and diffusion modes followed by coating delamination process on the toolsubstrate have been clearly identified. Moreover, a deformed layer was observed under secondaryelectron microscope (SEM) from the sub-surface of the chip with β-grains orientation along thechip flow direction. The analysis of the microstructure confirms the intense deformation of themachined surface and shows a texture modification, without phase transformation. For the Ti-555β-alloy, β grains experiences more plastic deformation and increases the microhardness of theworkpiece inducing then an abrasion wear process for cemented carbide tools. For the Ti6Al4Vmicrostructure, the temperature rise induces a thermal softening process of the workpiece andgenerates adhesive wear modes for cutting tools. The observed worn tool surfaces confirm theeffect of the microstructure on tool wear under different cutting conditions for the two studiedtitanium alloys.

scholarly journals In VitroandIn VivoActivities of the Novel Ketolide RBx 14255 against Clostridium difficile

2012 ◽  
Vol 56 (11) ◽  
pp. 5986-5989 ◽  
Author(s):  
Manoj Kumar ◽  
Tarun Mathur ◽  
Tarani K. Barman ◽  
G. Ramkumar ◽  
Ashish Bhati ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Time Dependent ◽  
Kinetics Study ◽  
The Novel ◽  
Promising Candidate ◽  
Hamster Model ◽  
Bacterial Killing ◽  
Content Type ◽  
Time Kill

ABSTRACTThe MIC90of RBx 14255, a novel ketolide, againstClostridium difficilewas 4 μg/ml (MIC range, 0.125 to 8 μg/ml), and this drug was found to be more potent than comparator drugs. Anin vitrotime-kill kinetics study of RBx 14255 showed time-dependent bacterial killing forC. difficile. Furthermore, in the hamster model ofC. difficileinfection, RBx 14255 demonstrated greater efficacy than metronidazole and vancomycin, making it a promising candidate forC. difficiletreatment.

scholarly journals Time-Dependent Reliability-Based Design Optimization Utilizing Nonintrusive Polynomial Chaos

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Yao Wang ◽  
Shengkui Zeng ◽  
Jianbin Guo
Keyword(s):  
Design Optimization ◽  
Structural Reliability ◽  
Polynomial Chaos ◽  
Time Dependent ◽  
Fe Model ◽  
Reliability Based Design Optimization ◽  
Wear Process ◽  
Reliability Based Design ◽  
Optimization Methodology ◽  
Wear Law

Time-dependent reliability-based design optimization (RBDO) has been acknowledged as an advance optimization methodology since it accounts for time-varying stochastic nature of systems. This paper proposes a time-dependent RBDO method considering both of the time-dependent kinematic reliability and the time-dependent structural reliability as constrains. Polynomial chaos combined with the moving least squares (PCMLS) is presented as a nonintrusive time-dependent surrogate model to conduct uncertainty quantification. Wear is considered to be a critical failure that deteriorates the kinematic reliability and the structural reliability through the changing kinematics. According to Archard’s wear law, a multidiscipline reliability model including the kinematics model and the structural finite element (FE) model is constructed to generate the stochastic processes of system responses. These disciplines are closely coupled and uncertainty impacts are cross-propagated to account for the correlationship between the wear process and loads. The new method is applied to an airborne retractable mechanism. The optimization goal is to minimize the mean and the variance of the total weight under both of the time-dependent and the time-independent reliability constraints.

SiO2 modified graphene oxide hybrids for improving fretting wear performance of ultra-high molecular weight polyethylene

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaocui Xin ◽  
Yunxia Wang ◽  
Zhaojie Meng ◽  
Fengyuan Yan
Keyword(s):  
Molecular Weight ◽  
Wear Resistance ◽  
High Molecular Weight ◽  
Design Methodology ◽  
Fretting Wear ◽  
Wear Performance ◽  
Content Type ◽  
Modified Graphene Oxide ◽  
Modified Graphene ◽  
Ultra High Molecular Weight

Purpose The purpose of this paper is to investigate the fretting wear performance of ultra-high-molecular-weight-polyethene (UHMWPE) with addition of GO and SiO2. Design/methodology/approach In this study, GO were synthesized and SiO2 nanoparticles were grafted onto GO. The effect of nanofiller on fretting wear performance of UHMWPE was investigated. Findings The results indicated that GO was successfully synthesized and SiO2 nanoparticles successfully grafted onto GO. Incorporation of GS was beneficial for the reduction in friction and the improvement in wear resistance of UHMWPE. GO was beneficial for reducing friction coefficient, while SiO2 was good for improving wear resistance. There existed a tribological synergistic effect between GO nanosheet and SiO2 nanoparticles. Research limitations/implications The hybrids of GS were promising nanofiller for improving the fretting wear performance of UHMWPE. Originality/value The main originality of the research is to reveal the effect of GO and SiO2 nanoparticles on fretting behavior of UHMWPE. The result indicated hybrids of GS were promising nanofiller for improving the fretting wear performance of UHMWPE.

A local radial basis function differential quadrature semi-discretisation technique for the simulation of time-dependent reaction-diffusion problems

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ram Jiwari ◽  
Alf Gerisch
Keyword(s):  
Meshless Method ◽  
Order Of Convergence ◽  
Method Of Lines ◽  
Reaction Diffusion ◽  
Diffusion Models ◽  
Second Order ◽  
Differential Quadrature ◽  
Time Dependent ◽  
Content Type ◽  
Radial Basis

Purpose This paper aims to develop a meshfree algorithm based on local radial basis functions (RBFs) combined with the differential quadrature (DQ) method to provide numerical approximations of the solutions of time-dependent, nonlinear and spatially one-dimensional reaction-diffusion systems and to capture their evolving patterns. The combination of local RBFs and the DQ method is applied to discretize the system in space; implicit multistep methods are subsequently used to discretize in time. Design/methodology/approach In a method of lines setting, a meshless method for their discretization in space is proposed. This discretization is based on a DQ approach, and RBFs are used as test functions. A local approach is followed where only selected RBFs feature in the computation of a particular DQ weight. Findings The proposed method is applied on four reaction-diffusion models: Huxley’s equation, a linear reaction-diffusion system, the Gray–Scott model and the two-dimensional Brusselator model. The method captured the various patterns of the models similar to available in literature. The method shows second order of convergence in space variables and works reliably and efficiently for the problems. Originality/value The originality lies in the following facts: A meshless method is proposed for reaction-diffusion models based on local RBFs; the proposed scheme is able to capture patterns of the models for big time T; the scheme has second order of convergence in both time and space variables and Nuemann boundary conditions are easy to implement in this scheme.

A Numerical Simulation of Fretting Wear considering the Dynamic Evolution of Debris for the Coated Contact Surface

2021 ◽  
pp. 1-49
Author(s):  
Li Xiao ◽  
Yingqiang Xu ◽  
Zhiyong Chen
Keyword(s):  
Fretting Wear ◽  
Contact Pair ◽  
Dynamic Evolution ◽  
Wear Depth ◽  
Wear Coefficient ◽  
Wear Model ◽  
Wear Process ◽  
Dlc Coating ◽  
Wear Life ◽  
Wear Calculation

Abstract In this paper, a multi-layer body model in which material properties and wear coefficient change with node coordinates is proposed, so that the wear profile is not restricted by the singularity of the interface of the coated contact pairs. The conversion rate of the adhered particles was obtained to describe the growth and expansion of the debris at the fretting interface based on experiments, and the wear model of coated contact pair considering the dynamic evolution of the debris layer was established. By comparing the previous experimental and computational results, the wear calculation method proposed in this paper is more reasonable to predict the wear profile of the coated contact pair. In addition, the influence of the debris layer on the wear depth, friction width, and contact pressure in the fretting process is analyzed, indicating that the existence of the debris layer can delay the wear process. Finally, the fretting wear life of the SCMV steel contact pair deposited with the W-DLC coating is estimated.

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