Effect of Lubrication on Friction in Bending under Tension Test-Experimental and Numerical Approach

This paper is aimed to determine the value of coefficient of friction (COF) at the rounded edge of the die in the sheet metal forming operations using the bending under tension (BUT) test. The experimental part of the investigations is devoted to the study of the frictional resistances of low alloy steel sheet under different strains of the specimen, surface roughnesses of the tool and for different lubrication conditions. Three oils are destined for different conditions of duties in the stamping process. Numerical modeling of the material flow in the BUT test has been conducted in the MSC.Marc program. One of the objectives of the numerical computations is to know the type of the contact pressure acting on the cylindrical surface countersample in the BUT test by assuming the anisotropic properties of the metallic sheet. It has been found that the COF in the rounded edge of the die does not vary with increasing sheet elongation. Taking into account that normal pressure increases with increasing specimen elongation and workpiece material is subjected to strain hardening phenomenon, the COF value is very stable during the friction test. The effectiveness of the lubrication depends on the balance between two mechanisms accompanied by friction process: roughening of workpiece asperities and adhesion of the contacting surfaces. In the case of high surface roughness of tool due to a dominant share of ploughing, all of the lubricants used were not able to decrease the COF in a sufficient extent. The used lubricants were able to reduce the value of friction coefficient approximately by 3–52% in relation to the surface roughness of rolls.publishedVersio

Recent developments and trends in the friction testing for conventional sheet metal forming and incremental sheet forming

Friction is the main phenomenon that has a huge influence on the flow behavior of deformed material in sheet metal forming operations. Sheet metal forming methods are one of the most popular processes of obtaining finished products, especially in aerospace, automobile, and defense industries. Methods of sheet forming are carried out at different temperatures. So, it requires tribological tests that suitably represent the contact phenomena related to the temperature. The knowledge of the friction properties of the sheet is required for the proper design of the conditions of manufacturing processes and tools. This paper summarizes the methods used to describe friction conditions in conventional sheet metal forming and incremental sheet forming that have been developed over a period of time. The following databases have been searched: WebofKowledge, Scopus, Baztool, Bielefield Academic Search Engine, DOAJ Directory of Open Access Journals, eLibrary.ru, FreeFullPdf, GoogleScholar, INGENTA, Polish Scientific Journals Database, ScienceDirect, Springer, WorldCat, WorldWideScience. The English language is selected as the main source of review. However, in a limited scope, databases in Polish and Russian languages are also used. Many methods of friction testing for tribological studies are selected and presented. Some of the methods are observed to have a huge potential in characterizing frictional resistance. The application of these methods and main results have also been provided. Parameters affecting the frictional phenomena and the role of friction have also been explained. The main disadvantages and limitations of the methods of modeling the friction phenomena in specific areas of material to be formed have been discussed. The main findings are as follows—The tribological tests can be classified into direct and indirect measurement tests of the coefficient of friction (COF). In indirect methods of determination, the COF is determined based on measuring other physical quantities. The disadvantage of this type of methods is that they allow the determination of the average COF values, but they do not allow measuring and determining the real friction resistance. In metal forming operations, there exist high local pressures that intensify the effects of adhesion and plowing in the friction resistance. In such conditions, due to the plastic deformation of the material tested, the usage of the formula for the determination of the COF based on the Coulomb friction model is limited. The applicability of the Coulomb friction model to determine the COF is also very limited in the description of contact phenomena in hot SMF due to the high shear of adhesion in total contact resistance.publishedVersio

Safety related study of Expanding Pin systems application in lifting and drilling equipment within Construction, Offshore, and Marine sectors

A questionnaire-based survey has been performed among original equipment manufacturers (OEMs), sub-suppliers, engineering companies, end-users, service & maintenance, and “others”, as part of an investigation to clarify their relationship to expanding pin system, compared to standard, cylindrical pins. In addition, a short literature study on onshore cranes is conducted. The survey is based on 9 questions about safety for personnel and machine, breakage, and wear of pins and supports, and installation and retrieval easiness of pins. The analysis of the responses indicates that safety for personnel and machines/equipment is regarded mainly as either “Important” or “Crucial and decisive”, and that the expanding pin solution is regarded as “better” or “equal” compared to the standard, cylindrical pin, both for “safety level”, “risk for breakage of pin & support”, “tear & wear on pin & support” and “installation and retrieval time”.publishedVersio

Literature Review on Thermomechanical Modelling and Analysis of Residual Stress Effects in Wire Arc Additive Manufacturing

The wire arc additive manufacturing (WAAM) process is a 3D metal-printing technique that builds components by depositing beads of molten metal wire pool in a layer-by-layer style. Even though manufactured parts commonly suffer from defects, the search to minimize defects in the product is a continuing process, for instance, using modeling techniques. In areas where thermal energy is involved, thermomechanical modeling is one of the methods used to determine the input thermal load and its effect on the products. In the WAAM fabrication process, the thermal load is the most significant cause of residual stress due to the extension and shrinkage of the molten pool. This review article explores the thermomechanical effect and stress existing in WAAM-fabricated parts due to the thermal cycles and other parameters in the process. It focuses on thermomechanical modeling and analysis of residual stress, which has interdependence with the thermal cycle, mechanical response, and residual stress in the process during printing. This review also explores some methods for measuring and minimizing the residual stress during and after the printing process. Residual stress and distortion associated with many input and process parameters that are in complement to thermal cycles in the process are discussed. This review study concludes that the thermal dependency of material characterization and process integration for WAAM to produce structurally sound and defect-free parts remain central issues for future research.publishedVersio

An investigation of the effects and consequences of combining Expanding Dual Pin with radial spherical plain bearings

An expanding pin locks the pin assembly to its supports and bearings and prevents any relative movements between the surfaces in contact. In this study, the diameter changes of the bearing inner ring as a function of the expanding pin’s tightening torque were studied. In addition, the required rotational moment of a set of complete bearings locked to an expanding pin solution was studied by exposing the assembly to a combination of an increasing radially outwards directed load from the bolt torquing and a radially external inwards directed load from a hydraulic jack. The bearings were of type Radial Spherical Plain Bearings (RSPBs), GE 80 ES, steel/steel, and loaded externally up to their maximum dynamic limit of 400 kN. The results indicate a major reduction in the required rotation moment of the bearing when the bearing inner ring is expanded by use of an expanding pin. The reduction of rotation moment indicates reduced contact pressure and friction force between the two bearing rings, which ultimately can have a reduced effect on ring surface wear and a positive effect on the bearing operational lifetime.publishedVersio

Design, simulation and production of hydraulic briquette press for metal chips

Removal of metal chips are involved in several industrial production processes that machine from casted parts by various operations such as turning, milling and drilling. In addition to the fact that the chips represent a treat to the environment, their storage requires a large surface area. The objective of the project reported in this article is to improve the current layout of a machining workshop aimed to minimize material handling cost, increase operator safety, improve flexibility for operation, minimize the overall cost and utilize the available area. The research project focused on the compaction of metal chips briquette for simplicity of storage as well as handling and transportation of metal chips for a factory named Hibret Manufacturing and Machine Building Industry (HMMBI). The machining process on CNC lathe and milling machines in this company produces 1500 – 2000 kg/month chip. An effective design of hydraulic briquette press is carried out by using solid modelling tool and the hydraulic circuit is simulated. The result of the designed machine is observed to address the stated problems of the company.publishedVersio

Experimental Investigation on Effect of Weight Fraction of Sisal Fiber on Mechanical Properties of Sisal-E-Glass Hybrid Polymer Composites

Currently, hybridizing natural fibers with synthetic fiber is considered as the best solution for reducing the environmental pollution and the cost of materials. This is due to the lower mechanical properties and high water absorption capacity problems of natural fiber reinforced composites and nonbiodegradability and high-cost problem of synthetic fibers that can be solved by hybridizing them. This article aims to investigate the influence of the weight fraction of the sisal fiber on the mechanical property of the E-glass-sisal fiber reinforced epoxy matrix composite. The sisal fiber was treated by 8% sodium hydroxide (NaOH) for three hours. The samples of five different weight fractions of fibers (0%, 20%, 30%, 40%, and 60%) with a constant weight fraction of epoxy matrix (40%) were prepared as per the ASTM standard prepared by the manual hand layup method at room temperature. The tensile, compression, and flexural tests of the samples were carried out on the WP 310 universal testing machine. From the experimental results, it has been observed that the increasing weight fraction of the sisal fiber greatly influences the mechanical properties (tensile, compression, and flexural) of E-glass-sisal hybrid reinforced epoxy matrix composites. From all the tested samples, those consisting of 60% E-glass and 0% sisal fibers with 40% epoxy matrix showed better mechanical properties than other hybrid samples with tensile, compressive, and flexural strengths of 464.03 MPa, 40.1 MPa, and 239.06 MPa, respectively.publishedVersio

Multiphysics Modeling and Numerical Simulation in Computer-Aided Manufacturing Processes

The concept of Industry 4.0 is defined as a common term for technology and the concept of new digital tools to optimize the manufacturing process. Within this framework of modular smart factories, cyber-physical systems monitor physical processes creating a virtual copy of the physical world and making decentralized decisions. This article presents a review of the literature on virtual methods of computer-aided manufacturing processes. Numerical modeling is used to predict stress and temperature distribution, springback, material flow, and prediction of phase transformations, as well as for determining forming forces and the locations of potential wrinkling and cracking. The scope of the review has been limited to the last ten years, with an emphasis on the current state of knowledge. Intelligent production driven by the concept of Industry 4.0 and the demand for high-quality equipment in the aerospace and automotive industries forces the development of manufacturing techniques to progress towards intelligent manufacturing and ecological production. Multi-scale approaches that tend to move from macro- to micro- parameters become very important in numerical optimization programs. The software requirements for optimizing a fully coupled thermo-mechanical microstructure then increase rapidly. The highly advanced simulation programs based on our knowledge of physical and mechanical phenomena occurring in non-homogeneous materials allow a significant acceleration of the introduction of new products and the optimization of existing processes.publishedVersio

Study of the Performance of Natural Fiber Reinforced Composites for Wind Turbine Blade Applications

Availability of some form of energy is essential for human survival and social development. However, the way energy has been generated within the last century has brought forward the quest for generation of energy without polluting the environment, which is nowadays considered to be the biggest global challenge. The materials used for wind turbine blades can be classified under this challenge of polluting the environment. One of the materials expected to reduce this problem is natural fiber reinforced composite (FRC). Thus, the focus of this paper is to evaluate the potential of different natural FRC materials for small wind turbine blade application. Eleven different natural fibers reinforced composite in epoxy resin are studied. The modified Halphin-Tsai semi-empirical model has been used to compute the physical properties of the composites, since it has a good agreement with experimental results. Stress, deformation, and weight of wind turbine blade under different loadings are analyzed aimed to search for a fiber type that may extend the life span of the blade. Finally, flap wise, edge wise, longitudinal and torsional natural frequencies are computed numerically by using finite element method in Qblade software (QFEM) under different mode types and the effects are analysed. Upon comparing the results with a common composite material for wind turbine blade (E-glass/epoxy), it has been observed that the selected natural fiber composites have equivalent and better mechanical performance. The environmental friendliness of natural fibers, i.e. biodegradability, comes as a plus to their advantage as materials of wind turbine blades.publishedVersio

Application of Artificial Intelligence for Surface Roughness Prediction of Additively Manufactured Components

Additive manufacturing has gained significant popularity from a manufacturing perspective due to its potential for improving production efficiency. However, ensuring consistent product quality within predetermined equipment, cost, and time constraints remains a persistent challenge. Surface roughness, a crucial quality parameter, presents difficulties in meeting the required standards, posing significant challenges in industries such as automotive, aerospace, medical devices, energy, optics, and electronics manufacturing, where surface quality directly impacts performance and functionality. As a result, researchers have given great attention to improving the quality of manufactured parts, particularly by predicting surface roughness using different parameters related to the manufactured parts. Artificial intelligence (AI) is one of the methods used by researchers to predict the surface quality of additively fabricated parts. Numerous research studies have developed models utilizing AI methods, including recent deep learning and machine learning approaches, which are effective in cost reduction and saving time, and are emerging as a promising technique. This paper presents the recent advancements in machine learning and AI deep learning techniques employed by researchers. Additionally, the paper discusses the limitations, challenges, and future directions for applying AI in surface roughness prediction for additively manufactured components. Through this review paper, it becomes evident that integrating AI methodologies holds great potential to improve the productivity and competitiveness of the additive manufacturing process. This integration minimizes the need for re-processing machined components and ensures compliance with technical specifications. By leveraging AI, the industry can enhance efficiency and overcome the challenges associated with achieving consistent product quality in additive manufacturing.publishedVersio