Design Of Machine Components Research Articles

Improving the reliability of the hammer grain crusher by optimal design of the paddle wheel

Now in agricultural production there are significant changes in the fleet of equipment due to the renewal of the material and technical base with improved parameters for quality, reliability, durability and operability in difficult operating conditions. However, the manufacturing industry still has a large number of outdated equipment that requires modernization through optimal design of machine components and parts. So, in the process of feed preparation, closed-type grain crushers are widely used, working on the principle of suction of the source material and injection of the finished product. This type of crushers undergoes significant abrasive wear of working bodies (drums, hammers, sieves, etc.) due to their suboptimal geometric shape of transition surfaces, where local stresses accumulate, as well as in areas of contact of parts with particles of gas-dispersed material. The blades of the drum wheel are subjected to particularly severe wear, for the restoration of which significant material costs are required during major repairs. The paper presents theoretical studies of contact stresses during wear of working surfaces, a criterion and condition for the optimal position of the blade are proposed. The optimal position of the blade has been determined - it must be positioned at an angle of 10 ° to the axis of the drum wheel. The results of field tests of the upgraded crusher allow us to conclude that the reliability indicators (durability of the blade drum and reliability of the crusher) increase by more than 3 times.

Knowledge-based decision support for machine component design: A case study

This paper describes research conducted during a project with a multinational company that focuses on product design. The project tackles two different goals: providing sales staff with a tool that allows them to autonomously handle routine requests, and providing the company’s engineers with a decision support system to help them design products for more challenging application areas. For the first goal, we make use of a deterministic decision process, represented in the recent Decision Model and Notation (DMN) standard. For the second goal, we propose a constraint-based method. There, we use the IDP system to provide a number of interactive functionalities based on a logical representation of the relevant constraints. To ensure that the system is maintainable, we want the constraints to be updated by the engineers themselves. The IDP language is not ideal for this. Instead, we propose the cDMN notation, which extends the user-friendly DMN to constraints.

Elasto-plastic behaviour of cantilever beams containing varied stress concentration cut out features

In machine component design, it is necessary to introduce openings or cut outs to carry out specific service functions such as electrical wiring, piping, and inspection, among others. The introduction of these cut outs results in a high concentration of stress leading to degradation of the component strength, especially under cyclic loading. The geometrical features and orientation of these cut outs relative to the support and the applied loads will also influence the severity of the resulting stress concentration. Of particular interest to this study is the elastic and elasto-plastic behaviour of a cantilever beam containing rectangular, circular or diamond cut outs under plane strain conditions. Four aspects of the work were accordingly examined. The first is concerned with the elasto-plastic load–deflection diagram of the beam containing the cut out features. The second with the finite element predictions of the elastic behaviour and the associated stress concentration factor of the beam in the presence of the cut out features. The third with the elasto-plastic behaviour and etching results showing the remarkable agreement between the two. Finally, in the fourth, we focus our attention to unloading residual stresses. The results offer a complete coverage of the problem and should help in the elasto-plastic design of beams containing stress concentration features.

Temperature Distribution Analysis of Composite Heat Sink (Pin Fin) by Experimental and Finite Element Method

Design of machine components plays a vital role in the field of Engineering where it includes the shape of component, size, applied loads, position and materials used. Due to the applied loads namely static, thermal and combined loads etc., the component undergoes stresses and deformations which affect the life of component and also the system. The Finite Element Method (FEM) is a numerical tool used for solving problems of engineering and mathematical problems in the fields of structural analysis, heat transfer, fluid flow, mass transport etc., For problems involving complicated geometries, loadings and material properties, it is generally not possible to obtain analytical solutions. These solutions generally require the ordinary or partial differential equations. Because of the complicated geometries, loadings and material properties, the solution can’t be obtained easily. So, in FEM the complicated shape of the component is divided in to small entities called elements. Element characteristics are studied and then all the elements are combined to make a single system of component. In the present work, Experiments have been conducted to find the temperature distribution within the pin fin made of composite metals and steady state heat transfer analysis has been carried using a finite element software ANSYS to test and validate results. The temperature distribution at different regions of pin fin are evaluated by FEM and compared with the results obtained by experimental work. The results are in good agreement and thus validated.

Design, development and testing of an auger‐assisted semi‐automatic coconut husking machine

AbstractCoconut husking is the primary and most difficult post‐harvesting operation among coconut processing. The physical properties of the coconuts such as length, diameter, perimeter, weight and husk thickness at the apex, at the pedicel end, at the ¼ from pedicel end, at the ½ from the pedicel end and at the ¾ from the pedicel end and the husk‐separating‐forces are calculated to design machine components. A prototype of an auger‐assisted semi‐automatic coconut husking machine (ASCHM) have designed, constructed, tested and its husking rate, husking effectiveness, husking efficiency, percent of nut breaking, and capacity of the machine has evaluated. The machine comprises mainly of a pair of upright blades; held juxtaposed for manual impaling, and an electrically‐driven auger. The mean time required for complete husking of green coconut and dry coconut have been found to be 12.6 s and 13.6 s respectively. The husking efficiency of ASCHM was found as 100% with no nut breaking with a capacity of 242 nuts/hr for green coconuts and 229 nuts/hr for dry coconuts. Further, performance of the developed tool has been compared with that of CPCH and KAU coconut husking tool.Practical ApplicationsMain contribution of this work is to design, development and testing of a semi‐automatic coconut husking machine and to analyze the performance of the same in terms of husking rate, husking effectiveness, husking efficiency, and percentage of nut breaking and capacity of the machine was evaluated. The results are then compared with those obtained for a manual and fully automated husking machine as well. Husk separating force calculation have been done considering the relevant physical properties of the coconut like size, shape, weight, and so forth. The observations are further then used for the design of machine components and the selection of a power source. The information deduced can be used as a database for future modifications as well as development of coconut husking machines.

A reduced-order method with PGD for the analysis of misaligned journal bearing

In recent years, machine component design has been a major concern for researchers. Emphasis has been placed especially on the analysis of bearing systems in order to avoid detrimental contact. The shaft misalignment is one of the most problems that affects directly the operating conditions of these components. In this context, the present study proposes a reduced-order method "Proper Generalized Decomposition" (PGD) using the separation technique through the alternating direction strategy to solve the modified Reynolds equation, taking into account the presence of misalignment in the shafting system. The solution shows the representation of two types of misalignment geometry, especially axial and twisting. A comparison of the results between the proposed approach and the classical method, through several benchmark examples, made it possible to highlight that the new scheme is more efficient, converges quickly and provides accurate solutions, with a very low CPU time expenditure.

Polymers in gearbox production

Technological progress spurs the creation of new machine designs, the development of new highly advanced technologies, as well as the introduction of new materials, including polymeric ones, that meet the economic and ecological criteria. An analysis of the literature reveals that there are few works outlining the rules for the design of machine components using polymeric materials, including composites and nanocomposites. This article is a review of the literature on the use of polymer matrix thermoplastic composites (PA6 – polyamide 6, PA66 – polyamide 66 and POM – polyoxymethylene) in toothed transmission systems. The presented examples demonstrate the production of hybrid polymer nanocomposites with addition of inorganic fillers and their application in the manufacture of machine components, including gears.

Modelling of tribological responses of composites using integrated ANN-GA technique

In the present article, artificial neural networks (ANNs) and genetic algorithm (GA) methodology were integrated to model tribological characteristics of stir-cast Al-Zn-Mg-Cu matrix composites under two-body abrasion considering large numbers of experimentally generated results. Tribo-responses of wear rate (Wrt), coefficient of friction (COF) and roughness of abraded surface (RAS) were evaluated under wide range of intrinsic ( i.e., particle quantity) and extrinsic ( i.e., abrasive size, load, distance and velocity) input parameters. Characteristics of Wrt, COF and RAS are often mutually contradictory in nature and so, multi-objective optimization technique becomes imperative for selection and design of machine components. Accordingly, those were optimized through Pareto solutions. Sensitivity of different factors was analyzed on each of the tribo-performances and validated via experimental evidences. Amongst the input variables, particle quantity and abrasive size dominated significantly over other variables except load which imparted modest influences. The role of various input parameters was explained through determination of different micromechanisms via exhaustive post wear characterizations, microstructural and surface topography attributes. Lowest values of Wrt and COF with a modest value of RAS were identified at 15 ± 2 wt.% particle quantity.

On the Strength Weakening Effect of Stiffening Ribs in the Design of Machine Components

The bending stress in beams may often be reduced by adding material to the cross section. In some paradoxical cases, however, the bending stress increases by adding material from zones far away, or close to, the neutral axis. Similarly, the bending stress of rectilinear or curved beams may often be reduced by adding ribs to the initial beam section. However, such ribs may sometimes cause a both undesired and unexpected stress increase, although they still produce a beneficial stiffening effect. The aim of this paper is twofold: a) to examine this unexpected result within the context of the paradoxical behaviour of some known beam sections, and especially of a recently noted paradox; b) to provide a preliminary rule of thumb for the mechanical design of ribs sometimes added to the outer surface of an eye, with particular regard to the small end of a connecting rod.

The Crack Analysis of Fatigue Tested Steel Construction

Laboratory fatigue testing is an important part of the fatigue design of machine components that are supposed to work under cyclic loading. These tests are used to confirm whether the tested component matches the required fatigue life and they also serve as a verification of the numerical calculations. This paper describes a fatigue life testing of a welded steel construction. The testing was carried out in the Regional Technological Institute (RTI) using an electro-hydraulic loading system, which allows realization of the tests simulating a real service. An integral part of the fatigue tests is a pre-scheduled inspection of the crack initiation and propagation. The tested construction was checked using non-destructive magnetic particle testing before the fatigue test and also during and after the performed test. Some cracks were observed, especially in the weld area. The biggest crack had the length of approximately 40 cm. This crack was cut out and underwent detailed metallographic and fractographic analysis to estimate the effect of material purity and quality of the weld on the fracture.

Assessment of Ultra-High Cycle Fatigue Behavior of EN-GJL-250 Cast Iron Using Ultrasonic Fatigue Testing Machine

High cycle fatigue comprising up to 107 load cycles has been the subject of many studies, and the behavior of many materials was recorded adequately in this regime. However, many applications involve larger numbers of load cycles during the lifetime of machine components. In this ultra-high cycle regime, other failure mechanisms play, and the concept of a fatigue endurance limit (assumed for materials such as steel) is often an oversimplification of reality. When machine component design demands a high geometrical complexity, cast iron grades become interesting candidate materials. Grey cast iron is known for its low cost, high compressive strength, and good damping properties. However, the ultra-high cycle fatigue behavior of cast iron is poorly documented. The current work focuses on the ultra-high cycle fatigue behavior of EN-GJL-250 (GG25) grey cast iron. An ultrasonic (20 kHz) fatigue testing system is developed and instrumented for testing at ambient temperature, and hourglass shaped cast iron specimens with circular cross-section are designed to be excited in resonance. The temperature of the specimen is measured using a pyrometer and controlled by ventilating air. The displacement at the free end of the specimen (which is linked to stress at the reduced section) is measured using an accurate laser sensor, whose analysis requires careful test preparation and data analysis. The high resonance frequency allowed to characterize the S-N behavior of the cast iron of interest within a matter of days, and repeat the tests to quantify the natural scatter in fatigue resistance. The obtained results will be used in a research project that aims to optimize the design of machine components with respect to weight and durability.

Principle of maximum entropy for reliability analysis in the design of machine components

We studied the reliability of machine components with parameters that follow an arbitrary statistical distribution using the principle of maximum entropy (PME). We used PME to select the statistical distribution that best fits the available information. We also established a probability density function (PDF) and a failure probability model for the parameters of mechanical components using the concept of entropy and the PME. We obtained the first four moments of the state function for reliability analysis and design. Furthermore, we attained an estimate of the PDF with the fewest human bias factors using the PME. This function was used to calculate the reliability of the machine components, including a connecting rod, a vehicle half-shaft, a front axle, a rear axle housing, and a leaf spring, which have parameters that typically follow a non-normal distribution. Simulations were conducted for comparison. This study provides a design methodology for the reliability of mechanical components for practical engineering projects.

Some Aspects of the Structure of Planar Mechanisms

The machine is a technical system made up of distinct kinematic component parts (called kinematic elements) which, following the imprinting of movements imposed on an element or elements (considered as leading elements), cause movements to all other kinematic elements in order to execute a useful mechanical thing, or transforming some form of energy into mechanical energy. It follows from the previous definition, three essential characteristics of the machine: the machine is a technical system; its kinematic elements have determined (desmodromic) movements; either to perform either a useful mechanical thing, calling it a lucrative machine, or transforming some form of energy into mechanical energy, bearing the name of a motor car. The lucrative machines are cars, locomotives, motor wagons, presses, machine tools, pumps, compressors, agricultural machines, lifting and transporting machines, etc. The motor vehicles are external combustion (Stirling, Watt) or internal combustion engines (Lenoir, Otto, Diesel, Wankel, star), turbines, hydraulic motors, reaction engines, pneumatic motors, electromagnetic), ionic engines, energy beam or LASER motors, etc. The most used mechanisms in machine building were and still maintain those that operate in a plane or in parallel planes. For this reason, new analytical methods have been developed and developed to determine all the essential aspects of these mechanisms in order to improve the design of machine components. For this reason, it is necessary to present a general presentation of the mechanism of the design of the mechanisms, the present paper dealing only with the first aspect, namely the structure of the planar mechanisms. The most common mechanisms are planar, with bars, toothed, with cams, with a mortar cross, with chains, with belts, with tracks, with bolts, with liquids (hydraulic or sonic), with air (pneumatic). However, spacecraft with universal cardan shaft (universal joint) and cardanic transmission, with hyperboloidal gears (with cross axles), with pivots (spherical couplings), especially steering and suspension mechanisms, tripod mechanisms, mechanisms with space cams, screw and nut mechanisms, robots, serial and parallel systems, steppers, etc. The mechanism, as we have already shown, is composed of kinematic elements connected by kinematic joints (or couplings).

Composites in Production Machines

This paper gives an overview of the design and application of composite materials in machine tools. Some exemplary machine elements, tool structures and components are introduced and the technical potentials, requirements and challenges are discussed. The presented prototypes and industrial products show that besides the lightweight construction aspect furthermore the specific mass related stiffness characteristics and the advantageous damping properties as well as the thermal behavior of composite structures provide outstanding chances regarding the improvement of the machine performance and accuracy. New degrees of freedom in machine component design and layout can be exploited especially if material combinations are implemented.

Mechanical design of machine components

Mechanical design of machine components

The Statistical Catastrophe Theory and Optimal Probability Based Design

This paper deals with the statistical catastrophe theory method for the optimal design of machine components. A short introduction to the catastrophe theory is presented, the statement of optimal design problem is given in the first part of the paper. A single criterion design is presented; the reliability function is used as the objective function. The last part is focused on probability approach. Manage variables are viewed as random stationary processes, statistical linearization method and Pearson moment method are used for the reliability function evaluation.

The Statement of Optimal Design Problem with the Cusp Catastrophe Theory Application

The purpose of this paper is to present the catastrophe theory method for the optimal design of machine components. A brief description of the cusp catastrophe is presented in the introduction. The statement of optimal design problem is given in the second part of the paper. A single criterion design is presented; the reliability function is used as the objective function. The last part is devoted to probability approach. Manage variables are viewed as stochastic quantities, analytical and statistical linearization methods are used for the reliability function evaluation.

Design and analysis of a prototypical sensory Z-slide for machine tools

Due to the advancements in high speed and high performance cutting, further improvements of machine component design and process monitoring are necessary. For this purpose, new machine components with process monitoring capabilities have to be developed. In this paper, a new spindle carrying Z-slide for a 5-axis machining center with integrated sensing capabilities for process monitoring is presented. First, the overall system design is described. The sensing capabilities to enable process monitoring are realized by application of a micro-strain gauges network on to the structure of the slide. The optimal sensor positions are computed by application of a special sensor placement algorithm. The prototype of the slide has been built up to investigate the system behavior. The electronic system of the prototype to realize the signal amplification and the communication via an industrial bus are presented. Furthermore, the results of the system analysis of the prototype are described. Because the sensor amplitudes, which can be monitored by strain gauges on stiff structures, are generally small, a method to increase these amplitudes by use of the notch effect and new micro-strain sensors is discussed. With this method, the signal amplitudes can be increased significantly, without degrading the stiffness noticeably. At the end of the paper a method to manufacture notches in the prototype by a milling process is presented. The surface roughness of plan notch ground, measured with a laserprofilometer, shows roughness values lower than 3 μm.

Prediction of Real Rough Surface Deformation in Pure Rolling EHL Contact: Comparison with Experiment

The ability to predict the in-contact deformation of surface topography is very important for the design of machine components with respect to minimizing the friction and wear of rubbing surfaces. In this study the amplitude attenuation principle is verified as a simple tool for this purpose. Measured lubricant film profiles are compared with prediction based on this principle. From the results obtained it appears that the amplitude attenuation principle provides reasonable estimation of the deformation of rubbing surfaces that can be used for the prediction of in-contact behavior of surface roughness. Good agreement was obtained under pure rolling conditions, which provides a good initial point for the other studies under rolling/sliding conditions where the wear of rubbing surfaces is of key importance.

Stress-Based Uniaxial Fatigue Analysis Using Methods Described in FKM-Guideline

The process of prevention of failure from structural fatigue is a process that should take place during the early development and design phases of a structure. In the ground vehicle industry, for example, the durability specifications of a new product are directly interweaved with the desired performance characteristics, materials selection, manufacturing methods, and safety characteristics of the vehicle. In the field of fatigue and durability analysis of materials, three main techniques have emerged: nominal stress-based analysis, local strain-based analysis, and fracture mechanics analysis. Each of these methods has their own strengths and domain of applicability—for example, if an initial crack or flaw size is known to exist in a structure, a fracture mechanics approach can give a meaningful estimate of the number of cycles it takes to propagate the initial flaw to failure. The development of the local strain-based fatigue analysis approach has been used to great success in the automotive industry, particularly for the analysis of measured strain time histories gathered during proving ground testing or customer usage. However, the strain life approach is dependent on specific material properties data and the ability to measure (or calculate) a local strain history. Historically, the stress-based fatigue analysis approach was developed first—and is sometimes considered an “old” approach—but the stress-based fatigue analysis methods have been continued to be developed. The major strengths of this approach include the ability to give both quantitative and qualitative estimates of fatigue life with minimal estimates on stress levels and material properties, thus making the stress-based approach very relevant in the early design phase of structures where uncertainties regarding material selection, manufacturing processes, and final design specifications may cause numerous design iterations. This article explains the FKM-Guideline approach to stress-based uniaxial fatigue analysis. The Forschungskuratorium Maschinenbau (FKM) was developed in 1994 in Germany and has since continued to be updated. The guideline was developed for the use of the mechanical engineering community involved in the design of machine components, welded joints, and related areas. It is our desire to make the failure prevention and design community aware of these guidelines through a thorough explanation of the method and the application of the method to detailed examples.