An Energy Approach for Helping the Selection of Solid Lubrication Coatings Under Fretting Conditions

2009 ◽  
Author(s):  
D. B. Luo ◽  
V. Fridrici ◽  
Ph. Kapsa ◽  
M. Taillandier ◽  
C. Prud’homme
Keyword(s):  
Master Curve ◽  
Initial Energy ◽  
Energy Approach ◽  
Friction Reduction ◽  
Solid Lubrication ◽  
Dissipated Energy ◽  
Test Parameters ◽  
Definition Of ◽  
Energy Dissipated ◽  
Fretting Damage

Employing friction reduction coatings is one of the most effective methods to palliate the fretting damage. However, facing numerous available coatings, how to compare them and select the optimum one for a specific application is still a challenging task. In this paper, based on the investigation of the fretting behaviors of several bonded solid lubricant coatings, an energy approach in terms of “initial maximal dissipated energy density” was suggested to compare the tribological response of coatings. According to test results, the lifetime of each coating under different test parameters can be fitted by one master curve. The definition of this master curve for a given coating may be used for the prediction of the coating lifetime only by knowing the initial energy dissipated in the contact. The comparison of different master curves for different coatings can be employed to help the coating selection.

Energy Dissipation by Micro-Slip in an Assembly, Analytic and Experimental Approach

2011 ◽  
Author(s):  
N. Peyret ◽  
J.-L. Dion ◽  
G. Chevallier ◽  
P. Argoul
Keyword(s):  
Loss Factor ◽  
Experimental Approach ◽  
Dynamic Behaviour ◽  
Dissipated Energy ◽  
Energy Losses ◽  
Non Linear ◽  
Definition Of ◽  
Linear Loss ◽  
Energy Dissipated ◽  
Experimental Bench

In structural dynamics, the problem of damping remains the biggest challenge. This paper deals with the energy losses caused by micro-slip in a planar interface of a structure. Taking into account friction in the joints during the analysis of dynamic systems remains a complex task. This paper proposes an analytical and experimental study of flexural vibrations of a clamped-clamped beam with innovative position of the interfaces. First, the benchmark is described and the choice of the position of the interface is justified. The displacement and stress fields are defined during each phase of the loading process in the joints under the assumption of quasi static motion. The energy dissipated by friction in the interface is calculated during a loading cycle. This leads to a definition of the dissipated energy, thus, to a non linear loss factor. The dynamic response of the beam is calculated using this non linear loss factor and a dissipative force is defined and used to predict the dynamic behaviour of the structure. In the last part of the paper, we present the experimental bench, and the dynamic behaviour of this structure. We propose to illustrate the mechanism of energy losses by micro-slip by making a comparison between the behaviour of the “monolithic” beam and the sectioned beam. Finally, we confront the loss factor calculated analytically and the measured one.

Modeling the Tensile Behaviour of a SiC/SiC Composite by Master Curves

2000 ◽  
Author(s):  
J. Shi
Keyword(s):  
Master Curve ◽  
Ceramic Matrix Composites ◽  
Test Material ◽  
Tensile Behaviour ◽  
Matrix Composites ◽  
Test Results ◽  
Master Curves ◽  
The Past ◽  
Test Parameters ◽  
Tensile Data

Scatter in test results is common for relatively brittle materials such as ceramic matrix composites. The scatter may come from differences in material processing conditions, specimen machining/handling and from variations in test parameters for nominally the same test material. Large scatter in test results makes material modeling difficult. In the past, master curve concepts have been proposed to reduce scatter in tensile data and to interpret fatigue/creep results. In this paper, one such concept is examined in detail by applying it to the recent tensile test results of a SiC/SiC composite. It was found that the way to construct master curves did not apply to the CMC studied and thus a new master curve was developed to better represent the tensile data. In addition, the test data were analysed statistically based on the new master curve.

A dissipated energy approach for flow number determination

2020 ◽  
pp. 347-350
Author(s):  
Hamzeh Saqer ◽  
Munir D. Nazzal ◽  
Mohammad Al-Khasawneh ◽  
Ala Abbas ◽  
Sang Soo Kim
Keyword(s):  
Energy Approach ◽  
Dissipated Energy ◽  
Flow Number

scholarly journals Dynamics of Assembled Structures: Taking Into Account the Surface Defects in Interfaces

2013 ◽  
Author(s):  
Nicolas Peyret ◽  
Gaël Chevallier ◽  
Jean-Luc Dion
Keyword(s):  
Loss Factor ◽  
Surface Defect ◽  
Test Bench ◽  
Surface Defects ◽  
Dissipated Energy ◽  
Energy Losses ◽  
Proposed Model ◽  
Nonlinear Loss ◽  
Energy Dissipated ◽  
Experimental Bench

In structural dynamics, the prediction of damping remains the biggest challenge. This paper deals with the energy losses caused by micro-slip in a nominally planar interface of a structure. This paper proposes an analytical and experimental study of flexural vibrations of a clamped-clamped beam with innovative position of the interfaces. The objective of this test bench is to characterize the global rheology of the interface. The proposed model aims to characterize this rheology based on local settings of the interface. First, the test bench is described and the choice of the position of the interface is justified. The experimental bench and the dynamic behavior of this structure are presented. We propose to illustrate the mechanism of energy losses by micro-slip by making a comparison between the behavior of a “monolithic” beam and a sectioned beam. Secondly, a modeling of the interface taking into account the surface defect is presented. The energy dissipated by friction in the interface is calculated during a loading cycle. This leads to a computation of the dissipated energy and thus to a nonlinear loss factor. Finally, we confront the loss factor calculated analytically and the measured one.

Large-Scale Discrete-Time Interconnected Dynamical Systems

2011 ◽  
Author(s):  
Wassim M. Haddad ◽  
Sergey G. Nersesov
Keyword(s):  
Dynamical Systems ◽  
Discrete Time ◽  
Large Scale ◽  
Discrete Energy ◽  
Flow Balance ◽  
Subsystem Level ◽  
Coupling Strengths ◽  
Definition Of ◽  
Energy Dissipated ◽  
Discrete Time Dynamical Systems

This chapter develops vector dissipativity notions for large-scale nonlinear discrete-time dynamical systems. In particular, it introduces a generalized definition of dissipativity for large-scale nonlinear discrete-time dynamical systems in terms of a vector dissipation inequality involving a vector supply rate, a vector storage function, and a nonnegative, semistable dissipation matrix. On the subsystem level, the proposed approach provides a discrete energy flow balance in terms of the stored subsystem energy, the supplied subsystem energy, the subsystem energy gained from all other subsystems independent of the subsystem coupling strengths, and the subsystem energy dissipated. The chapter also develops extended Kalman–Yakubovich–Popov conditions, in terms of the local subsystem dynamics and the interconnection constraints, for characterizing vector dissipativeness via vector storage functions for large-scale discrete-time dynamical systems.

Optimal Vibration Control and Energy Scavenging Using Collocated Nonlinear Energy Sinks and Piezoelectric Elements

2018 ◽  
Author(s):  
Zahra Nili Ahmadabadi ◽  
Siamak Esmaeilzadeh Khadem
Keyword(s):  
Piezoelectric Element ◽  
Dissipated Energy ◽  
Vibration Energy ◽  
Energy Scavenging ◽  
Optimization Approach ◽  
Energy Harvesters ◽  
Energy Pumping ◽  
Nonlinear Energy Pumping ◽  
Energy Dissipated ◽  
Nonlinear Energy

This paper presents an optimal design for a system comprising multiple nonlinear energy sinks (NESs) and piezoelectric-based vibration energy harvesters attached to a free–free beam under shock excitation. The energy harvesters are used for scavenging vibration energy dissipated by the NESs. Grounded and ungrounded configurations are examined, and the systems parameters are optimized globally to maximize the dissipated energy by the NESs. The performance of the system was optimized using a dynamic optimization approach. Compared to the system with only one NES, using multiple NESs resulted in a more effective realization of nonlinear energy pumping particularly in the ungrounded configuration. Having multiple piezoelectic elements also increased the harvested energy in the grounded configuration relative to the system with only one piezoelectric element.

Relationship Between Charpy V-Notch Impact Value and Fracture Mechanics Toughness: Added Value of Finite Element Analysis and Instrumented Impact Tests

2011 ◽  
Author(s):  
Philippe Thibaux ◽  
Filip Van den Abeele ◽  
Philippe Burlot
Keyword(s):  
Finite Element ◽  
Master Curve ◽  
Impact Test ◽  
Crack Arrest ◽  
Smooth Transition ◽  
Unstable Crack ◽  
Impact Tests ◽  
The Difference ◽  
Energy Dissipated ◽  
The Impact

Each structure is designed with resistance versus the fracture, which requires the knowledge of the fracture resistance of the material. If no fracture mechanics data of the material is available, a KJC can be inferred from the master curve approach. The master curve approach relates a fracture toughness of 100 MPAm1/2 to the impact transition temperature T27J with a shift of 18°C. Although this relationship was successfully applied to a large number of experiments, some steels deviate significantly from the previous relationship, which can even lead to non-conservative design. In the present paper, instrumented impact tests (Charpy V-Notch CVN) and compact tensile (CT) tests were performed on two materials, one thermomechanically (TM-) rolled and one normalized steel. The difference between T0 and T27J was found to be different for these materials. Furthermore, the normalized steel exhibits a smooth transition from brittle to ductile behaviour, while the TM-rolled material shows a very steep transition. Extra information is gained by combining the instrumentation of the impact test and the finite element simulations of both the CT and impact tests. From the instrumented tests, it is also possible to determine the load at unstable crack propagation, the amount of energy dissipated at that moment, the load at crack arrest and the energy dissipated after crack arrest. From the finite element simulation, one learns about the constraints ahead of the crack tip for both configurations. The investigation teaches us that the smooth transition of the normalized material is related to a high energy dissipated after crack arrest, while the TM-rolled material has a much lower crack arrest load. The difference between T0 and T27J is then discussed by decomposing the total energy in the impact test between crack initiation, propagation and arrest. It is compared with KJC, which determines the toughness at unstable crack propagation, by reviewing the literature and local stress states computed from finite element.

Study on Friction Reduction and Wear Resistance Process and Composition of FeS Solid Lubrication Duplex Layer

2012 ◽  
Vol 502 ◽  
pp. 60-66 ◽  
Author(s):  
Chun Hua Hu ◽  
Jia Ping Zou ◽  
Jiu Juan Qian ◽  
Ding Yun Jin ◽  
Xiao Feng Sun
Keyword(s):  
Wear Resistance ◽  
Surface Layer ◽  
Diffusion Layer ◽  
Steel Surface ◽  
Friction Reduction ◽  
Solid Lubrication ◽  
Wear Volume ◽  
Load Bearing Capacity ◽  
Lubricating Property ◽  
Plain Surface

The composition of FeS solid lubrication duplex layer on 45 steel surface was studied by using SEM, EDS, AES and XPS. The results show that the sulphurized surface layer of FeS solid lubrication duplex is composed of the sulphide aggradation layer deposited on the nitrocarburized sub-surface layer and the sulphide diffusion layer formed by some S element infiltrating the nitrocarburized surface. The sulphide aggradation layer is mainly composed of FeS and FeS2, the key composition of the sulphide diffusion layer is FeS, and Fe(2/3/4)N is the key composition of the nitrocarburized sub-surface layer. The result of friction reduction and wear resistance test combined with the composition of FeS solid lubrication duplex layer explains that the friction coefficient and wear volume of the duplex layer are lower than those of the plain surface, which attribute to the relatively softer sulphurized surface layer provided self-lubricating property while the harder nitrocarburized sub-surface layer provided sufficient load bearing capacity in view of resistance to plastic deformation, so that spallation failure of the sulphurized surface layer can be effectively avoided, and they exert excellent friction reduction and wear resistance functions in different moments during rubbing process respectively.

Scanning High-Efficiency Air Filters for Leaks Using Particle Counting Methods

1993 ◽  
Vol 36 (5) ◽  
pp. 28-37
Author(s):  
Bruce McDonald
Keyword(s):  
Flow Rate ◽  
High Efficiency ◽  
Particle Detectors ◽  
Air Filters ◽  
Test Parameters ◽  
Counting Methods ◽  
Scan Rate ◽  
Particle Counts ◽  
Definition Of ◽  
Individual Particles

High-efficiency particulate air (HEPA) filters and ultra low penetration air (ULPA) filters such as those used in cleanrooms and clean benches are frequently scanned or probed for leaks. Increasingly, particle detectors that count individual particles are used to scan filters. The equations that govern the scanning of high-efficiency filters with particle counters have been derived. The assumptions that bound the applicability of the equations are stated. The relationships provide the means to determine the appropriate linear scan rate and to understand the effect of the test parameters on the duration and accuracy of the test. The linear scan rate is derived in terms of a leak flow rate but a method is presented to relate the leak flow to the traditional leak penetration. Further, a method is described to standardize the definition of leak penetration to eliminate the dependence of measured leak penctration on the instrument used to measure it. The linear scan rate is shown to depend on the number of particle counts used to characterize the threshold leak. The statistical impact of the count used to calculate the linear scan rate is described.

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