scholarly journals A method for handlebars ballast calculation in order to reduce vibrations transmissibility in walk behind tractors

2017 ◽  
Vol 48 (2) ◽  
pp. 81 ◽  
Author(s):  
Angelo Fabbri ◽  
Chiara Cevoli ◽  
Giuseppe Cantalupo
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Experimental Tests ◽  
Dynamic Structure ◽  
Average Percentage ◽  
Percentage Difference ◽  
Average Percentage Difference ◽  
Vibration Transmissibility ◽  
High Level

Walk behind tractors have some advantages over other agricultural machines, such as the cheapness and the easy to use, however the driver is exposed to high level of vibrations transmitted from handles to hand-arm system and to shoulders. The vibrations induce discomfort and early fatigue to the operator. In order to control the vibration transmissibility, a ballast mass may be added to the handles. Even if the determination of the appropriate ballast mass is a critical point in the handle design. The aim of this research was to study the influence of the handle mass modification, on the dynamic structure behaviour. Modal frequencies and subsequent transmissibility calculated by using an analytical approach and a finite elements model, were compared. A good agreement between the results obtained by the two methods was found (average percentage difference calculated on natural frequencies equal to 5.8±3.8%). Power tillers are made generally by small or medium-small size manufacturers that have difficulties in dealing with finite element codes or modal analysis techniques. As a consequence, the proposed analytical method could be used to find the optimal ballast mass in a simple and economic way, without experimental tests or complex finite element codes. A specific and very simple software or spreadsheet, developed on the base of the analytical method here discussed, could effectively to help the manufacturers in the handlebar design phase. The choice of the correct elastic mount, the dimensioning of the guide members and the ballast mass could be considerably simplified.

An Investigation on Bending Capacity of Support Stiffness Wall-Slab Structural System by Using Single Layer and Double Layer of Rebar for Residential Project

2012 ◽  
Vol 446-449 ◽  
pp. 3670-3673
Author(s):  
Hooi Min Yee ◽  
Siti Isma Hani Ismail
Keyword(s):  
Double Layer ◽  
Concrete Strength ◽  
Single Layer ◽  
Concrete Cover ◽  
Structural System ◽  
Average Percentage ◽  
High Rise ◽  
Percentage Difference ◽  
Average Percentage Difference ◽  
Bending Capacity

Wall-slab structural system is a system suitable for use in the field of high-rise building where the main load resisting system is in the form rigidly connected wall slab member. Concrete vertical walls may serve both architecturally partitions and structurally to carry gravity and lateral loading. Moment transfer of joint is an important aspect for proper structurally functioning of wall-slab system. Hence, the main aim of this study is to investigate experimentally the effect of reinforcement details in the wall on bending capacity for support stiffness in wall-slab system for residential project in Malaysia. A total of six wall specimens were tested based on the specification given by the project contractor. Three of this specimens consisted single layer of rebar while another three specimen consisted of double layer of rebar. The size of the wall-slab’s specimens is 1000mm in length (L), 1080mm in width (W), 1000mm in height (H) and 80mm in thickness (T). The average concrete strength was 23.49MPa with Grade 30N/mm2 and the average yield strength of R5 bar was 817MPa. The predicted bending capacity at failure is in the range from 5.36kNm to 7.12kNm, depending on actual concrete cover. The bending capacity at failure for single layered of rebar in wall for specimen 1, 2 and 3 were found to be 3.59kNm, 3.81kNm and 3.15kNm, respectively. The bending capacity at failure for double layered of rebar in wall for specimen 1, 2 and 3 were 5.50kNm, 6.31kNm and 7.00kNm, respectively. The average percentage difference in stiffness of double layered of rebar in wall based on load-deflection curve obtained is in the range from 116.17% to 289.88% higher than single layered of rebar in wall. Based on the experimental results, specimens consisted of double layered of rebar in wall is found to provide higher bending capacity to the joint of wall-slab structural system in the range from 56.25% to 98.86% compared with single layered of rebar in wall.

Study of bolted joint axial stiffness using finite element analyses, experimental tests, and analytical calculations

2020 ◽  
Vol 234 (23) ◽  
pp. 4671-4681
Author(s):  
Raphael Calazans Cardoso ◽  
Brenno Lima Nascimento ◽  
Felipe de Freitas Thompson ◽  
Sandro Griza
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
High Reliability ◽  
Experimental Tests ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Bolted Joint ◽  
Finite Element Analyses ◽  
Load Distributions ◽  
Reliable Design

The bolted joints sizing procedures shall adequately match the conditions imposed on the joint in service, to ensure high reliability designs. Therefore, this study aims to analyze the load distributions on the bolt when applying external load on bolted joints. Finite element and extensometry analyses as well as analytical calculations were performed in order to compare the magnitude of the joint overall stiffness, with respect to several available theories. The results acquired through the analytical method prescribed in the VDI 2230 standard as well as the finite element and extensometry analyses obtained great accordance. These results indicate that VDI 2230 standard adequately represents the mechanical behavior of the joint and should be used as a guideline for the reliable design of bolted joints subjected to the loading conditions of the present paper.

SIMULATION OF INTAKE AND EXHAUST VALVE TIMING ON INTERNAL COMBUSTION ENGINE

2017 ◽  
Vol 79 (7-4) ◽  
Author(s):  
Afiq Aiman Dahlan ◽  
Mohamad Shahrafi ◽  
Mohd Farid Muhamad Said
Keyword(s):  
Internal Combustion Engine ◽  
Power Output ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Exhaust Valve ◽  
Miller Cycle ◽  
Average Percentage ◽  
Percentage Difference ◽  
Average Percentage Difference ◽  
Opening And Closing

Internal combustion engine in automotive industry is widely researched to increase its efficiency and power output. Valve system in modern internal combustion engine control the opening and closing timing of intake and exhaust stroke. Its duration affects the performance of the engine at both power output and fuel efficiency. Therefore, this study discusses about the Miller cycle concept that alter the duration of both intake and exhaust valve opening and closing characteristics. The study focusses mainly on finding the optimum timing characteristics on Proton Iriz gasoline engine. A 1-dimensional model has been built using a commercial software called GT-POWER for engine simulation purpose. The engine is then calibrated with the simulation model. The optimization was run in this software to find the best optimum timing of intake and exhaust valve for two categories which are targeting performance and fuel consumption. The results show positive trends in the BSFC results with the maximum percentage difference of 26.27% at 6,250 rpm. The average percentage difference in the BSFC results is 14.12%. For targeting performance, the overall results show an increasing trend in the brake torque curves with maximum percentage difference is 9.83%. The average percentage difference in brake torque is found to be 3.12%. Therefore, this paper concludes that Miller cycle implementation give minimal performance increment. The targeting performance and fuel consumption optimization can also be implement for changing mode of driving. However, the increase compression ratio would also give adverse effects on engine performance and endurance. The Miller cycle is also more suitable to be implement on force induction system. 

scholarly journals Performance of pulsed-electrochemical honing and pulsed-electrochemical finishing in improving quality of bevel gears

2018 ◽  
Vol 5 ◽  
pp. 14 ◽  
Author(s):  
Sunil Pathak ◽  
Neelesh Kumar Jain
Keyword(s):  
Surface Roughness ◽  
Removal Rate ◽  
Bevel Gear ◽  
Average Percentage ◽  
Bevel Gears ◽  
Pitch Error ◽  
Percentage Difference ◽  
Average Percentage Difference ◽  
Electrochemical Finishing

This article presents a comparative study concerning performance of pulsed-electrochemical honing (PECH) and pulsed-electrochemical finishing (PECF) in straight bevel gear finishing. Performance of these processes were compared in terms of average percentage difference in the considered parameters of surface features of bevel gear namely average percentage differences in average surface roughness ‘PDRa’, maximum surface roughness ‘PDRmax’ and depth of surface roughness ‘PDRz’, micro-geometry (i.e. average percentage differences in single pitch error ‘PDfp’, adjacent pitch error ‘PDfu’, cumulative pitch error ‘PDFp’, and percentage difference in runout ‘PDFr’) and finishing productivity (i.e. material removal rate ‘MRR’). Microstructure and microhardness were also considered as measure for performance assessment. Observed results show PECH is proficient in simultaneously improving all the considered responses of bevel gears by more than 50% as compared to PECF. The PECH-finished gear additionally displayed unrivalled microstructure and better microhardness when contrasted with PECF-finished gear. These changes will upgrade the working-life and operating performance of the finished gear.

scholarly journals Design of Semi-Submersible Platform using Computational Fluid Dynamics

2020 ◽  
Vol 9 (3) ◽  
pp. 3888-3892
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Average Percentage ◽  
Eddy Simulation ◽  
Velocity Magnitude ◽  
Percentage Difference ◽  
Average Percentage Difference ◽  
The Difference ◽  
Volume Method

This paper reports based on an experimental study to simulate flow due to irregular fluid flow in a semi-submersible platform using computational fluid dynamics. In this paper we use computational fluid dynamics tools which solve simple differential equations and finite volume method (FVM). A turbulence model is considered i.e. large eddy simulation (LES). The semi-submersible model is considered as pontoons, columns, horizontal brace and deck. The pontoons are horizontal placed stadium shaped structures which are submerged into the water. The columns are structures which connect the deck and pontoons in these model circular columns are considered. The horizontal braces are circular tube-like structures which connect the two or more columns which increases the rigidity of the columns. The deck is a flat surface which provides workable area. This paper is a comparison of fluid flow at different velocity magnitude. The velocity contour, pressure contour and streamline contour are simulated and graphically represented. The numerical simulations are compared with experimental solutions and focus on vicinity of the platform. The difference in pressure, temperature and streamline flow are tabulated and graphically represented. The average percentage difference in temperature and pressure are calculated to be 73% and 128% respectively. Thus, the causation is investigated for the case and several governing parameters are recognized.

Combined empirical–analytical method for determining contact radius and indenter displacement during Hertzian indentation on coating/substrate systems

2004 ◽  
Vol 19 (9) ◽  
pp. 2774-2781 ◽  
Author(s):  
Chun-Hway Hsueh ◽  
Pedro Miranda
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Empirical Equation ◽  
Contact Radius ◽  
Finite Element Analyses ◽  
Modulus Ratio ◽  
Properties Of Coatings ◽  
Hertzian Indentation ◽  
Potential Applications

An analytical model was developed in a previous work to relate the normalized indenter displacement to both the coating-to-substrate Young's modulus ratio and the coating-thickness-to-contact-radius ratio for Hertzian indentation on coating/substrate systems. However, application of this model is contingent upon the determination of the contact radius during indentation. Using the data from finite element analyses, an empirical equation is proposed in this paper to determine the normalized contact radius. Combining this empirical equation with the previous analytical equation, both the contact radius and the indenter displacement for Hertzian indentation on coating/substrate systems are predicted. The predictions obtained by this combined empirical–analytical method are shown to agree with the finite element results in general although the indenter displacement is over-estimated when the coating is stiffer than the substrate. Finally, the potential applications of this method to determine the elastic properties of coatings from the indentation data are envisaged.

scholarly journals Random Stiffness Tensor of Particulate Composites with Hyper-Elastic Matrix and Imperfect Interface

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6676
Author(s):  
Damian Sokołowski ◽  
Marcin Kamiński
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Analytical Method ◽  
Volume Fraction ◽  
Effective Stiffness ◽  
Particulate Composites ◽  
Stiffness Tensor ◽  
The Matrix ◽  
Hyper Elastic

The main aim of this study is determination of the basic probabilistic characteristics of the effective stiffness for inelastic particulate composites with spherical reinforcement and an uncertain Gaussian volume fraction of the interphase defects. This is determined using a homogenization method with a cubic single-particle representative volume element (RVE) of such a composite and the finite element method solution. A reinforcing particle is spherical, located centrally in the RVE, surrounded by the thin interphase of constant thickness, and remains in an elastic reversible regime opposite to the matrix, which is hyper-elastic. The interphase defects are represented as semi-spherical voids, which are placed on the outer surface of this particle. The interphase is modeled as hyper-elastic and isotropic, whose effective stiffness is calculated by the spatial averaging of hyper-elastic parameters of the matrix and of the defects. A constitutive relation of the matrix is recovered experimentally by its uniaxial stretch. The 3D homogenization problem solution is based upon a numerical determination of strain energy density in the given RVE under specific uniaxial and biaxial stretches as well as under shear deformations. The analytical relation of the effective composite stiffness to the input uncertain parameter is recovered via the response function method, using a polynomial basis and an optimized order. Probabilistic calculations are completed using three concurrent approaches, namely the iterative stochastic finite element method (SFEM), Monte Carlo simulation and by the semi-analytical method. Previous papers consider the composite fully elastic, which limits the applicability of the resulting effective stiffness tensor computed therein. The current study voids this assumption and defines the composite as fully hyper-elastic, thus extending applicability of this tensor to strains up to 0.25. The most important research finding is that (1) the effective stiffness tensor is sensitive to random interface defects in its hyper-elastic range, (2) its resulting randomness is not close to Gaussian, (3) the semi-analytical method is not perfectly suited to stochastic calculations in this region of strains, as opposed to the linear elastic region, and (4) that the increase in random dispersion of defects volume fraction has a much higher effect on the stochastic characteristics of this stiffness tensor than fluctuation of the strain.

scholarly journals Determination of the Rayleigh damping coefficients of steel bristles and clusters of bristles of gutter brushes

DYNA ◽  
2015 ◽  
Vol 82 (194) ◽  
pp. 230-237
Author(s):  
Libardo Vicente Vanegas Useche ◽  
Magd M Abdel Wahab ◽  
Graham A Parker
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Experimental Tests ◽  
The Road ◽  
Damping Coefficients ◽  
Dynamic Finite Element ◽  
Rayleigh Damping ◽  
Dynamic Analyses ◽  
Effective Operation

Street sweeping is an important service that is usually performed by lorry-type vehicles that have a gutter brush, which is comprised of clusters of steel bristles that sweep the debris found in the road gutter. Effective operation of this brush is important, as most of the debris on roads is located in the gutter. In order to model a gutter brush by means of finite element dynamic analyses, it is necessary to determine appropriate values of the Rayleigh damping coefficients of both individual bristles and clusters of bristles. This paper presents the methodology and results of experimental tests that have been conducted to determine these coefficients. The results obtained are useful when studying the performance of conventional and oscillatory street sweeper gutter brushes by means of dynamic finite element modeling.

scholarly journals RANCANG BANGUN SISTEM PENGOLAHAN CITRA DIGITAL UNTUK MENENTUKAN BERAT BADAN IDEAL

2017 ◽  
Vol 2 (2) ◽  
pp. 63
Author(s):  
Toni Efendi ◽  
Tsurayya Ats Tsauri ◽  
Iin Intan Uljanah
Keyword(s):  
Image Processing ◽  
Human Body ◽  
Search Algorithm ◽  
Detection Algorithm ◽  
The Body ◽  
Actual Condition ◽  
Ideal Weight ◽  
Average Percentage ◽  
Percentage Difference ◽  
Average Percentage Difference

In actual fact, there are many people who do not know whether their weight have been ideal or not due to unavailable device or machine that can be used to measure ideal weight practically. Therefore, in order to measure the ideal weight practically, the researcher is attempting to create a system based on image processing which is developed by using Matlab software. As a preliminary step, the researcher collects some samples data that will be used in the research. Furthermore, the calculation formula is analysed by the researcher to be used in the system. This research is using a formula namely Body Surface Area (BSA) with a tubular analogy of human body. Image processing is made by using the edge detection algorithm to know the height and width of objects in an image of the human body. In addition, by certain search algorithm the height and width of object in the image of human body will be known and used for measuring approximate height and weight. Besides, Body Mass Index (BMI) formula is used for measuring ideal weight. the research shows that the value of the average percentage difference deviation of the system is 1.63% for height and 11.6% for weight. At least but not last, for the level of system accuracy reaching up to 75% of the body actual condition by system calculating result.

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