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Editorial Office

University of Ljubljana
Faculty of Mechanical Engineering
Journal of Mechanical Engineering

Aškerčeva 6,

SI-1000 Ljubljana
Slovenia

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E: info@sv-jme.eu



The journal is subsidized by Slovenian Research Agency.

 
ISSN: 0039-2480

Journal of Mechanical Engineering 63 (2017) 1

 

 

 


 

Optimal Wavelet Selection for the Size Estimation of Manufacturing Defects of Tapered Roller Bearings with Vibration Measurement using Shannon Entropy Criteria

Authors - Krisztián Deák* – Tamás Mankovits – Imre Kocsis


Abstract

Fault diagnosis of bearings is essential in manufacturing to increase quality. Traditionally, fault diagnosis of tapered roller element bearings is performed by signal processing methods, which handle the nonstationary behaviour of the signal. The wavelet transform is an efficient tool for analysing the vibration signal of the bearings because it can detect the sudden changes and transient impulses in the signal caused by faults in the bearing elements. In this article, manufacturing faults on the outer ring of tapered roller bearings due to the grinding process in manufacturing are investigated. Nine different real values wavelets (Symlet-2, Symlet-5, Symlet-8, db02, db06, db10, db14, Meyer, and Morlet) are compared according to the Energy-to-Shannon-Entropy ratio criteria, and which is efficient for detecting the manufacturing faults is determined. Finally, experiments are carried out on a test rig for determining the geometrical size of the manufacturing faults with all wavelets directly from the vibration signature the result of db02, Symlet-5, and Morlet wavelets are presented. When modelling the bearing structure as an under-damped second-order mass-spring-damper mechanical system, its unit impulse response function is compared to the wavelets on the basis of their Energy-to-Shannon-Entropy ratio to determine the fault size from the vibration signal. The proposed technique has been successfully implemented for measuring defect widths. The maximum deviation in result has been found to be 4.12 % for the defect width which was verified with image analysis methods using an optical microscope and contact measurement.

Keywords - condition monitoring, bearing vibration analysis, wavelet, entropy, dynamic model

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 3-14, SI 3
DOI:10.5545/sv-jme.2016.3989

 

pdfOptimal Wavelet Selection for the Size Estimation of Manufacturing Defects of Tapered Roller Bearings with Vibration Measurement using Shannon Entropy Criteria (.pdf 2.3MB)

 


  

Improvement of the Lubrication Performance of RBD Palm Stearin as an Alternative Lubricant under Different Sliding Speeds

Authors - Nurul Farhanah Azman* – Syahrullail Samion


Abstract

Vegetable oils have gained global att–ention to be used as an alternative lubricant to reduce the dependency on natural resources of petroleumbased lubricants due to concern over environmental problems. In this study, a refined, bleached and deodorized (RBD) palm stearin was chosen as the base lubricant, and its lubrication performance was investigated using a pin-on-disk tribotester. A zinc dialkyl-dithiophosphate (ZDDP) additive in concentrations of 1 wt%, 3 wt% and 5 wt% was blended with RBD palm stearin to improve the lubrication performance of the base lubricant. Commercial semi-synthetic oil (SAE15W50) was used for comparison purposes. The experiments were conducted under various sliding speeds (1.5 ms-1, 2.5 ms-1 and 3.5 ms-1) under normal force of 9.81 N for an hour. The lubrication performance of the tested lubricants was presented by the coefficient of friction, wear scar diameter, wear rate, surface roughness and wear worn surface of the pin specimen. The results show that an increase in ZDDP concentrations has improved the lubrication performance of the RBD palm stearin. RBD palm stearin with 5 wt% ZDDP additive shows a smaller coefficient of friction than that of SAE15W50, but creates a slightly larger wear scar diameter and wear rate.

Keywords - RBD palm stearin, ZDDP, coefficient of friction, wear rate

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 15-24, SI 4
DOI:10.5545/sv-jme.2016.3746

 

pdfImprovement of the Lubrication Performance of RBD Palm Stearin as an Alternative Lubricant under Different Sliding Speeds (.pdf 1.4MB)

 


 

Linear and Quadratic Solid-Shell Elements for Quasi-Static and Dynamic Simulations of Thin 3D Structures: Application to a Deep Drawing Process

Authors - Peng Wang – Hocine Chalal – Farid Abed-Meraim*


Abstract

A family of prismatic and hexahedral solid–shell (SHB) elements, with their linear and quadratic versions, is proposed in this work to model thin structures. The formulation of these SHB elements is extended to explicit dynamic analysis and large-strain anisotropic plasticity on the basis of a fully three-dimensional approach using an arbitrary number of integration points along the thickness direction. Several special treatments are applied to the SHB elements in order to avoid all locking phenomena and to guarantee the accuracy and efficiency of the simulations. These solid-shell elements have been implemented into ABAQUS standard/quasi-static and explicit/dynamic software packages. A number of static and dynamic benchmark problems, as well as a simulation of the deep drawing of a cylindrical cup, have been conducted to assess the performance of these SHB elements.

Keywords - assumed-strain method, finite elements, linear and quadratic solid–shell, quasi-static and dynamic, thin 3D structures, deep drawing

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 25-34, SI 5
DOI:10.5545/sv-jme.2016.3526

 

pdfLinear and Quadratic Solid-Shell Elements for Quasi-Static and Dynamic Simulations of Thin 3D Structures: Application to a Deep Drawing Process (.pdf 1.6MB)

 


 

Robust Fault-Tolerant Control of In-Wheel Driven Bus with Cornering Energy Minimization

Authors - András Mihály – Péter Gáspár – Balázs Németh


Abstract

The aim of this paper is to design fault-tolerant and energy optimal trajectory tracking control for a four-wheel independently actuated (FWIA) electric bus with a steer-by-wire steering system. During normal driving conditions, the architecture of the proposed controller enables the bus to select an energy optimal split between steering intervention and torque vectoring, realized by the independently actuated in-wheel motors by minimizing the cornering resistance of the bus. In the case of skidding or a fault event of an in-wheel motor or the steering system, a high-level control reconfiguration using linear parameter varying (LPV) techniques is applied to reallocate control signals in order to stabilize the bus. The main novelty of the paper is the control reconfiguration method based on the specific characteristics of the in-wheel bus which enables introducing such scheduling variables, with which the safety and efficiency of the FWIA bus can be enhanced.

Keywords - In-wheel motor, FWIA bus, reconfigurable control, cornering resistance


Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 35-44, SI 6
DOI:10.5545/sv-jme.2016.3639

 

pdfRobust Fault-Tolerant Control of In-Wheel Driven Bus with Cornering Energy Minimization (.pdf 1.1MB)




Research of Planetary Gear Fault Diagnosis Based on Multi-Scale Fractal Box Dimension of CEEMD and ELM

Authors - Xihui Chen – Gang Cheng* – Hongyu Li – Yong Li

Abstract

The planetary gear is the most critical part of a drive transmission system, and its faults will affect the reliability of the equipment, and even cause accidents. Therefore, it is of great significance to study the fault diagnosis of the planetary gear. A method of planetary gear fault diagnosis based on the multi-scale fractal box dimension of complementary ensemble empirical mode decomposition (CEEMD) and extreme learning machine (ELM) is proposed. The original vibration signal is decomposed by CEEMD, and a series of intrinsic mode functions (IMFs) are obtained. Some effective IMFs are extracted, and their reconstructed signal associated with the feature information is obtained. The reconstructed signal is analysed with multi-scale analysis, and the fault feature information contained in the signals with different scales is quantified and extracted via a fractal box dimension. The status recognition of planetary gear is achieved by combining ELM. The experiments show that the proposed method is effective at diagnosing planetary gear faults.

Keywords - Fault diagnosis, Planetary gear, CEEMD, Multi-scale, Fractal box dimension, ELM

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 45-55, SI 7
DOI:10.5545/sv-jme.2016.3811

 

pdfResearch of Planetary Gear Fault Diagnosis Based on Multi-Scale Fractal Box Dimension of CEEMD and ELM (.pdf 3.3MB)




Modelling Length/Pressure Hysteresis of a Pneumatic Artificial Muscle using a Modified Prandtl-Ishlinskii Model

Authors - Yixiang Liu – Xizhe Zang* – Zhenkun Lin – Xinyu Liu – Jie Zhao


Abstract

Pneumatic artificial muscles have been widely used in various fields owing to their inherent compliance and high power-to-weight ratio. However, the natural hysteresis nonlinearity including length/pressure hysteresis and force/pressure hysteresis degrades their performance in precise tracking control, making it necessary to build a mathematical hysteresis model for hysteresis compensation. This paper deals with the modelling of length/pressure hysteresis of pneumatic artificial muscles. The length/pressure hysteresis loops measured by the isotonic test are found to be asymmetric and independent of the external load when the load is small. Considering that the classical Prandtl-Ishlinskii model is only effective for symmetric hysteresis, a modified Prandtl-Ishlinskii model is proposed to describe the length/pressure hysteresis behaviour. The developed model utilizes two asymmetric operators with simple mathematical forms to independently model the ascending branch and descending branch of hysteresis loops. The model parameters are identified using the recursive least square algorithm. Comparisons between simulation results and experimental measurements demonstrate that the proposed model can characterize the asymmetric major hysteresis loop and minor hysteresis loops with high accuracy.

Keywords - asymmetric hysteresis, length/pressure hysteresis, modified Prandtl-Ishlinskii model, pneumatic artificial muscles, recursive least square algorithm


Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 56-64, SI 8
DOI:10.5545/sv-jme.2016.4027

 

pdfModelling Length/Pressure Hysteresis of a Pneumatic Artificial Muscle using a Modified Prandtl-Ishlinskii Model (.pdf 1.4MB)

 



Model Reduction of a Load-Sensing Hydraulic System via Activity Index Analysis

Authors - Quanyi Hu* – Hong Zhang – Shujun Tian – Xuxin Qin

Abstract

A load-sensing hydraulic system is an energy-saving fluid power transmission that supplies “on-demand” flow at a prescribed pressure margin greater than load pressure. In the paper, based on bond graph methodology, a complex and non-linear load-lensing (LS) hydraulic system model is constructed, in which the dynamic behaviours of an LS valve are taken into account. Moreover, a series of experiments are performed to validate the model. Two reduced models based on activity index analysis are obtained to achieve a balance between accuracy and complexity. The results indicate that the system order and computation time can be reduced. By quantifying the relative importance of the elements based on activity index analysis, it shows that the inner leakage of the pump plays a major role in system dynamics due to its correlation to the damping coefficient. Furthermore, the results prove the rationality of representing LS pump dynamics with a fourth-order differential equation and the fact that the dynamics of LS valves have not been well-covered in the literature.

Keywords - load-sensing, bond graph, modelling, model reduction, activity index, MORA

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 63(2017)1, 65-77, SI 9
DOI:10.5545/sv-jme.2016.3450

 

pdfModel Reduction of a Load-Sensing Hydraulic System via Activity Index Analysis (.pdf 2.9MB)

 


 


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