Journal of Mechanical Engineering 57 (2011) 7-8

 

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Simulating Nonlinear Materials under Centrifugal Forces by using Intelligent Cross-Linked Simulations

Authors - Reinhard Hackenschmidt ‒ Bettina Alber-Laukant ‒ Frank Rieg

Abstract

Actual sophisticated development processes are conducted by the use of multiple computer-aided tools (CAx-tools) to accelerate product development. However, because of below optimal simulation strategies and procedure guidelines mainly for complex materials and loading the development process is constricted and hence sluggish. The main emphasis of the article is to show how Intelligent CROsslinked Simulations (ICROS) methodical approach can be used to handle complex processes supported by specific computer techniques employed. Development of an elastomer insert subassembly for a standard claw coupling is used as an example of such a complex process.

Keywords - product development, CAx, ICROS, FEA, simulation, workflow

Paper's information

Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 531-538
DOI:10.5545/sv-jme.2011.013

Simulating Nonlinear Materials under Centrifugal Forces by using Intelligent Cross-Linked Simulations (.pdf 2.2MB)

 

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Validation of a Flexible Multibody Belt-Drive Model

Authors - Gregor Čepon ‒ Lionel Manin ‒ Miha Boltežar

Abstract

In the past decade the applicability of belt-drives has been extended significantly due to their increased reliability. With automotive engines it is now common to join a large number of belt-drives into a single, long belt-drive with several tensioner pulleys. However, these belt-drives can exhibit complex dynamic behaviors; therefore it is very important to predict the dynamics response of such systems using validated numerical models.
The aim of this paper is to perform the validation of a developed belt-drive model. The validation of this belt-drive model was performed using a two-pulley belt-drive. The numerically obtained results are compared with experimental data under various operational conditions. Finally, the applicability of the belt-drive model is presented by simulating a serpentine belt-drive, considering non-steady, belt-drive operational conditions.

Keywords - belt-drive, validation, ANCF, angular speed loss, serpentine belt-drive

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 539-546
DOI:10.5545/sv-jme.2010.257

 

Validation of a Flexible Multibody Belt-Drive Model (.pdf 2.8MB)

 

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Integrated Design for Fatigue Life Estimation of Structures

Authors - Radouane Akrache ‒ Jian Lu

Abstract

The design of a product or a mechanical system involves several stages, starting with the development of product specifications and ending with its final destruction. The aim of our research is to develop appropriate tools by proposing new operating methodologies and new computer tools to link up material development process with the mechanical design. In the first part, we will outline the overall approach adopted, and describe an integrated design method for estimating the fatigue life of mechanical structures. In the second part, we will discuss prestressing processes and take them into account in our approach. The third part is devoted to developing a calculation code for determining the multiaxial fatigue life of 3D structures.

Keywords - multiaxial fatigue life, integrated design, finite element method, fatigue criteria

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 547-554
DOI:10.5545/sv-jme.2008.043

Integrated Design for Fatigue Life Estimation of Structures (.pdf 787KB)

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Mesh Smoothing with Global Optimization under Constraints

Authors - Simon Kulovec ‒ Leon Kos ‒ Jožef Duhovnik

Abstract

Mesh (pre)processing remains an important issue for obtaining useful meshes used in mechanical engineering, especially for finite element calculations. An efficient and robust combination of constrained mesh smoothing together with global optimization based algorithm is presented. In contrast to other “popular” mesh smoothing algorithms that use only local diffusion approaches to smoothing we propose Lagrange-Newton Sequential Quadratic Optimization (LNO) with constraints that can satisfy local and global cost functions, respecting posed constraints. Local cost function is modeled with local average edge length, while global cost function includes barycenter and global average edge length.
Experiments with triangular, quadrilateral, and mixed meshes show flexibility of the proposed method to achieve near ideal elements for given input meshes. Convergence is presented for several 2D and 3D meshes. Various additional goals can be mixed over the area of interest with applied weights. In contrast to other methods, unconstrained meshes still preserve their global shape while improving local quality.

Keywords - smoothing, sequential quadratic optimization, SQO, mesh structure, geometry, vertex, cost function

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 555-567
DOI:10.5545/sv-jme.2010.113

Mesh Smoothing with Global Optimization under Constraints (.pdf 2.0MB)

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Study of Adaptive Model Parameter Estimation for Milling Tool Wear

Authors - Chuangwen Xu ‒ Ting Xu ‒ Qi Zhu ‒ Hongyan Zhang

Abstract

In a modern machining system, tool wear monitoring systems are needed to get higher quality production. In precision machining processes, especially surface quality of the manufactured part can be related to tool wear. This increases industrial interest for in-process tool wear monitoring systems. For the modern unmanned manufacturing process, an integrated system composed of sensors, signal processing interface and intelligent decision making model are required. In this study, a new method for on-line tool wear monitoring is presented under varying cutting conditions. The proposed method uses wear feature extraction based on process modeling and parameter estimation. An adaptive estimation model of milling tool wear in variable cutting parameters is built based entirely on milling power. The adaptive model traces the properties of cutting process by combining process state signal, cutting conditions, power model. The tool wear feature is obtained from the estimated parameters of the model and carried on in the theoretical and experimental study. Experiment results have proved that changes of the parameters in the cutting power model significantly indicate tool wear independently of varying cutting conditions and it makes tool wear a recognized process with high precision.

Keywords - milling power, adaptive estimation model, tool wear, model parameters, information fusion

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 568-578
DOI:10.5545/sv-jme.2009.138

Study of Adaptive Model Parameter Estimation for Milling Tool Wear (.pdf 1.3MB)

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Numerical Modelling of Crack Growth in a Gear Tooth Root

Authors - Srđan Podrug ‒ Srečko Glodež ‒ Damir Jelaska

Abstract

A computational model for determination of crack growth in a gear tooth root is presented. Two loading conditions are taken into account: (i) normal pulsating force acting at the highest point of the single tooth contact and (ii) the moving load along the tooth flank. In numerical analysis it is assumed that the crack is initiated at the point of the largest stresses in a gear tooth root. The simple Paris equation is then used for a further simulation of the fatigue crack growth. The functional relationship between the the stress intensity factor and crack length K = f(a), which is needed for determining the required number of loading cycles N for a crack propagation from the initial to the critical length, is obtained using a displacement correlation method in the framework of the FEM-method considering the effect of crack closure. The model is used for determining fatigue crack growth in a real gear made from case carburised and ground steel 14CiNiMo13-4, where the required material parameters were determined previously by appropriate test specimens. The results of the numerical analysis show that the prediction of crack propagation live and crack path in a gear tooth root are significantly different for both loading conditions considered.

Keywords - gears, fatigue, crack growth, numerical modelling

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 579-586
DOI:10.5545/sv-jme.2009.127

Numerical Modelling of Crack Growth in a Gear Tooth Root (.pdf 1.2MB)

 

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Design and Testing of an Ultrasound System for Targeted Spraying in Orchards

Authors - Viktor Jejčič ‒ Tone Godeša ‒ Marko Hočevar ‒ Brane Širok ‒ Aleš Malneršič ‒ Andrej Štancar ‒ Mario Lešnik ‒ Denis Stajnko

Abstract
The research aims to demonstrate the basic system elements of a prototype automated orchard sprayer, which can deliver pesticide spray selectively with respect to the characteristics of the targets. The contour of the apple tree canopy was detected by ultra sound sensors Prowave 400EP14D and appropriate electronics. Ultra sound signal was processed by a personal computer and fed in real-time to spraying nozzles which open and close in relation to the canopy structure. The current project focuses on developing the system components for spraying an individual tree. The evaluation was performed in field experiments by detecting deposits on leaves and water sensitive papers (WSP). The demonstrated concept of precise application of pesticide sprays supports a decrease in the amount of delivered spray, thereby reducing both costs and environmental pollution by plant protection products.

Keywords - air-assisted sprayer, ultra sound, algorithm, spray distribution, orchard

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 587-598
DOI:10.5545/sv-jme.2011.015

Design and Testing of an Ultrasound System for Targeted Spraying in Orchards (.pdf 1.9MB)

 

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Integrating R&D and Marketing in New Product Development

Authors - Nuša Fain ‒ Mihael Kline ‒ Jožef Duhovnik

Abstract
R&D - marketing integration is considered to be a critical activity within New Product Development (NPD). A theoretical framework for the study of R&D - marketing integration levels developed by Gupta et al (1986) is one of the most widely cited R&D - marketing integration frameworks in scientific literature. It is based on the presumption that strategy, environmental, organizational and individual factors are those determining R&D - marketing integration levels and consequently NPD success. Several empirical studies have been conducted to test this framework, however most of them have dealt only with portions of Gupta et al (1986)'s model. This paper is an attempt to put forward and test an integrated research protocol for the study of R&D - marketing integration, based on this theoretical framework. Empirical evidence gained from a questionnaire survey and two company case studies show, that people active within the R&D - marketing interface perceive the studied constructs as relevant for R&D - marketing integration, thus giving confirmation to Gupta et al (1986)’s model. The presented research protocol can therefore be considered as a valid start into R&D - marketing integration research within an integrated framework.

Keywords - marketing, R&D, integration, NPD, theoretical framework, empirical evidence

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 599-609
DOI:10.5545/sv-jme.2011.004

Integrating R&D and Marketing in New Product Development (.pdf 452KB)

 

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Virtual Engine - A Tool for a Powertrain Dynamic Solution

Authors - Vaclav Pistek ‒ Pavel Novotny

Abstract
The paper presents computational and experimental approaches to a powertrain vibration analysis. A complex computational model of a powertrain - a virtual engine is a powerful tool for a solution of structural, thermal and fatigue problems. The virtual engine results should answer different questions, mainly those concerning the area of noise, vibrations and component fatigues. The paper also includes a description of fast algorithm for a hydrodynamic solution of a slide bearing incorporating pin tilting influences. The main contribution is the fact that all models, that is those of a cranktrain, a valvetrain, a gear timing mechanism and a fuel injection pump are solved simultaneously, using a complex computational model. Synchronous solutions can have a fundamental effect on results of powertrain dynamics solutions. Additionally, it might help to understand influences among powertrain parts. The virtual engine is assembled as well as numerically solved in Multi Body System. Virtual engine results are validated by measurements on Diesel in-line six-cylinder engine.

Keywords - vibrations, noise, dynamics, powertrain, hydrodynamics

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 610-621
DOI:10.5545/sv-jme.2009.076

Virtual Engine - A Tool for a Powertrain Dynamic Solution (.pdf 2.0MB)

 

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Computation of Stress Intensity Factor in Functionally Graded Plates under Thermal Shock

Authors - Mohammad Bagher Nazari ‒ Mahmoud Shariati ‒ Mohammad Reza Eslami ‒ Behrooz Hassani

Abstract
This paper addresses the implementation of the element-free Galerkin method, which is enriched intrinsically for fracture analysis of functionally graded materials under mode I steady-state and transient thermal loading. The stress intensity factors are evaluated by means of both equivalent domain integral and displacement correlation technique. Continuum functions and the micromechanical model are used to describe the distribution of material properties. For thermal shock analysis, the modal decomposition method, which is a semi-discretization approach, is implemented to obtain the transient temperature field. Also, few parametric analyses are performed to study the effect of material gradation on the stress intensity factors. The results imply that the magnitude of the stress intensity factor reaches its peak a short while after the thermal shock, indicating its significant role in the fracture failure.

Keywords - functionally graded materials, element-free Galerkin method, equivalent domain integral, displacement correlation technique, thermal stresses

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 57(2011)7-8, 622-632
DOI:10.5545/sv-jme.2010.138

Computation of Stress Intensity Factor in Functionally Graded Plates under Thermal Shock (.pdf 0.9MB)

 

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