Showing papers on "Material flow published in 2018"

Effects of pin thread on the in-process material flow behavior during friction stir welding: A computational fluid dynamics study

Abstract: Pin thread is one of the most common geometrical features for the friction stir welding (FSW) tools. The main purpose of employing the pin thread is to improve the in-process material flow behaviors during FSW. However, it has not been fully understood how exactly the pin thread influences the material flow because of the lack of in-process observation. In this study, we aim to analyze the effect of pin thread on the in-process material flow during FSW of an Al-Mg-Zn alloy by using numerical simulation based on computational fluid dynamics (CFD). In our numerical simulation, the transient rotation of the threaded pin is implemented explicitly via fully transient control of the zone motion, and the mechanical interaction at the tool-workpiece interface is considered via the recent developed shear-stress-based frictional boundary condition. The numerical simulation has been validated by the experimental measured temperatures at 8 different locations, the distribution of marker materials and the geometry of deformation zone in the weld. Based on the numerical simulation results, three effects of the pin thread on the material flow have been elucidated. First, accelerated flow velocity and enhanced strain rate is induced owing to the use of the pin thread, which is attributed to the fact that the interfacial sticking is preferable inside the thread groove opening. Second, the pin thread has an effect to trap material in the high-velocity zone inside the thread groove opening, which causes a many-circle flow pattern around the threaded pin. Third, the pin thread contributes to a vertical pressure gradient, which is important for the in-process material transfer from the top to the bottom. The approaches and concepts in this study can be applied for further fundamental investigation of FSW and the computer aided design of the welding tools.

Effect of the Tool Tilt Angle on the Heat Generation and the Material Flow in Friction Stir Welding

Abstract: This work studies the effect of the tool tilt angle on the generated heat and the material flow in the work pieces joint by Friction Stir Welding (FSW). An apropos kinematic framework together with a two-stage speed-up strategy is adopted to simulate the FSW problem. The effect of tilt angle on the FSWelds is modeled through the contact condition by modifying an enhanced friction model. A rotated friction shear stress is proposed, the angle of rotation depending on the process parameters and the tilt angle. The proposed rotation angle is calibrated by the experimental data provided for a tilt angle 2.5°. The differences of generated heat and material flow for the cases of tool with tilt angle of 0° and 2.5° are discussed. It is concluded that due to the higher temperature, softer material and greater frictional force in the trailing side of the tool, the material flow in the rear side of the FSW tool with the title angle is considerably enhanced, which assists to prevent the generation of defect.

Finite element simulation of pin shape influence on material flow, forces in friction stir welding

Abstract: Selection of tool geometry is an important aspect for an efficient friction stir welding (FSW), as it influences material flow, forces, and other output responses. In the present paper, a three-dimensional coupled thermo-mechanical model is proposed based on Lagrangian method to evaluate the performance of two different pin shapes, i.e., smooth conical and threaded conical. Experimentally obtained axial force and spindle torque are used to validate the model. Particle tracking method is used to visualize the material flow on advancing side, retreating side, and centerline of the weld. Results reveal that material flow is non-symmetric and unstirred region is lower for the threaded pin as compared to the smooth. Higher slip rate is predicted for threaded pin as compared to the smooth pin. Vertical flow is observed for the threaded pin and is almost negligible for smooth pin.

Integrating High-Resolution Material Flow Data into the Environmental Assessment of Waste Management System Scenarios: The Case of Plastic Packaging in Austria

Abstract: The environmental performance of the waste management system of plastic packaging in Austria was assessed using a combination of high-resolution material flows and input-dependent life cycle invent...

Numerical modelling and experimental investigation of thermal and material flow in probeless friction stir spot welding process of Al 2198-T8

Abstract: A finite element model based on software Abaqus/Explicit and experimentation was established to describe the probeless friction stir spot welding process of 2198-T8 aluminium alloy. An Arbitrary La...

Texture Development and Material Flow Behavior During Refill Friction Stir Spot Welding of AlMgSc

Abstract: The microstructural evolution during refill friction stir spot welding of an AlMgSc alloy was studied. The primary texture that developed in all regions, with the exception of the weld center, was determined to be 〈110〉 fibers and interpreted as a simple shear texture with the 〈110〉 direction aligned with the shear direction. The material flow is mainly driven by two components: the simple shear acting on the horizontal plane causing an inward-directed spiral flow and the extrusion acting on the vertical plane causing an upward-directed or downward-directed flow. Under such a complex material flow, the weld center, which is subjected to minimal local strain, is the least recrystallized. In addition to the geometric effects of strain and grain subdivision, thermally activated high-angle grain boundary migration, particularly continuous dynamic recrystallization, drives the formation of refined grains in the stirred zone.

Finite-element simulation and validation of material flow in thermal drilling process

Abstract: Galvanized steel is broadly employed in metal roofing, air conditioning duct, support beams, construction materials, and domestic appliances, etc. In conventional drilling method has limitations such as asymmetrical holes, as well as formation of crack inside the hole made in sheet metal. This problem was entirely exterminated in thermal drilling (TD) process. In the course of TD process, the high temperature was developed due to rotational and feed rate of thermal drill into the workpiece. Owing to this reason, the thermal drill pierces workpiece effortlessly. However, in this process, workpiece deformation is very high; therefore, finite-element simulation is used to study the material flow which is challenging in experimental method. According to finite-element method (FEM), the finite-element analysis of TD process was conducted by the DEFORM-3D simulation software. The aim of this study is to conduct an experimental investigation of TD process on galvanized steel (GS), and then, it is compared to numerical results obtained from the FEM. Between experimental and FEM simulation of TD process, a good relationship was found.

Material flow and void defect formation in friction stir welding of aluminium alloys

Abstract: An ingenious experimental programme by combining artificially thickened oxide layer as marker material and ‘stop-action’ welding were used to study the material flow and defect formation in frictio...

High-Strain-Rate Material Behavior and Adiabatic Material Instability in Impact of Micron-Scale Al-6061 Particles

Abstract: Impact of spherical particles onto a flat sapphire surface was investigated in 50-950 m/s impact speed range experimentally and theoretically. Material parameters of the bilinear Johnson–Cook model were determined based on comparison of deformed particle shapes from experiment and simulation. Effects of high-strain-rate plastic flow, heat generation due to plasticity, material damage, interfacial friction and heat transfer were modeled. Four distinct regions were identified inside the particle by analyzing temporal variation of material flow. A relatively small volume of material near the impact zone becomes unstable due to plasticity-induced heating, accompanied by severe drop in the flow stress for impact velocity that exceeds ~ 500 m/s. Outside of this region, flow stress is reduced due to temperature effects without the instability. Load carrying capacity of the material degrades and the material expands horizontally leading to jetting. The increase in overall plastic and frictional dissipation with impact velocity was found to be inherently lower than the increase in the kinetic energy at high speeds, leading to the instability. This work introduces a novel method to characterize HSR (109 s−1) material properties and also explains coupling between HSR material behavior and mechanics that lead to extreme deformation.

Finite element analysis of material flow in die-less clinching process and joint strength assessment

Abstract: In the present work, a numerical investigation of the effect of the blank holder parameters on material flow and the final geometry of the die-less clinched joint is conducted. Various blank holder designs as well as different process parameters are used to obtain clinched joints. Axisymmetric finite element (FE) model was developed to simulate die-less clinching experiments. A hybrid material model with a weight function between the two common used hardening laws, Swift and Voce, was utilized to better represent the material behavior in the FE model. Another hybrid material model, referred to as extended-Voce model, was also utilized in the FE simulation and the results compared with the weight function approach. The weight function material model resulted in smaller geometric interlock compared with the experiment, whereas, the extended-Voce model led to better prediction of experimental geometric interlock with an error of less than 5%. The results showed that the interlock forms due to a large material flow in the axial and radial directions. The interlock can be maximized by controlling the material to flow in radial direction instead of axial direction, by decreasing blank holder depth. Also, distortion of the bottom of the die-less clinched joint can be avoided by achieving a bottom thickness of at least 10% of the total sheet thickness. Lastly, finite element models were also developed to predict the joint strength in shear and peel failure modes.

Dynamic Material Flow Analysis-Based Life Cycle Optimization Framework and Application to Sustainable Design of Shale Gas Energy Systems

Abstract: We propose a novel modeling framework integrating the dynamic material flow analysis (MFA) approach with life cycle optimization (LCO) methodology for sustainable design of energy systems. This dynamic MFA-based LCO framework provides high-fidelity modeling of complex material flow networks with recycling options, and it enables detailed accounting of time-dependent life cycle material flow profiles. The decisions regarding input, output, and stock of materials are seamlessly linked to their environmental impacts for rigorous quantification of environmental consequences. Moreover, by incorporating an additional dimension of resource sustainability, the proposed modeling framework facilitates the sustainable supply chain design and operations with a more comprehensive perspective. The resulting optimization problem is formulated as a mixed-integer linear fractional program and solved by an efficient parametric algorithm. To illustrate the applicability of the proposed modeling framework and solution algori...

Operations flow effectiveness: a systems approach to measuring flow performance

Abstract: Effective operations management systems (OMS) measurement remains a critical issue for theorists and practising managers (Neely, 2005; Bititci et al., 2012). Traditional labor efficiency measures sufficed when all that was made could be sold or when mass production systems filled warehouses with stock and the OMS had little relationship with “the consumer.” Modern manufacturing systems require a different form of flow optimization (beyond labor efficiency) measurement (Schmenner, 2015). The essential unit of measure for all OMS designs is the optimal use of time for process value adding and the flow of materials into and from the conversion process. Timely flow, therefore, satisfies the needs of multiple organizational stakeholders including cash flow (accounting), consumer reaction times (marketing) and the general steady state flow of materials (sales and supply chain). The purpose of this paper is to present the results of testing a new performance measure of operations flow effectiveness (OFE) with ten purposively selected cases.,The paper is theory building using ten, purposively selected, longitudinal case studies drawn from the UK high-value manufacturing (HVM) sector using a pluralist methodology of interviews, observation and secondary data.,The OFE measure provides a holistic view of material flow through the input-process-output cycles of a firm. The measure highlights OMS design weaknesses and flow inhibitors that reduce cash flow using a time-based approach to measuring OMS performance. The study validates the OFE measure and has identified six key design elements that enable high flow performance.,The paper tests a new process-focused flow performance measure. The measure supports a holistic approach to the manufacturing enterprise and allows different OMS designs to be evaluated so that organizational learning may be enacted to support performance improvement.

Influence of Tool Tilt Angle on Material Flow and Defect Generation in Friction Stir Welding of AA2219

Abstract: Heat treatable aluminium alloy AA2219 is widely used for aerospace applications, welded through gas tungsten and gas metal arc welding processes Welds of AA2219 fabricated using a fusion welding process suffers from poor joint properties or welding defects due to melting and re-solidification Friction stir welding (FSW) is a solid-state welding process and hence free from any solidification related defects However, FSW also results in defects which are not related to solidification but due to improper process parameter selection One of the important process parameters, ie, tool tilt angle plays a critical role in material flow during FSW, controlling the size and location of the defects Effect of tool tilt angle on material flow and defects in FSW is ambiguous A study is therefore taken to understand the role of tool tilt angle on FSW defects Variation in temperature, forces, and torque generated during FSW as a result of different tool tilt angles was found to be responsible for material flow in the weld, controlling the weld defects An intermediate tool tilt angle (1o-2o) gives weld without microscopic defect in 7 mm thick AA2219 for a given set of other process parameters At this tool tilt angle, x-force, and Z- force is balanced with viscosity and the material flow strain rate sufficient for the material to flow and fill internal voids or surface defects in the weld

Energy and material flow modelling of additive manufacturing processes

Abstract: Additive manufacturing (AM) processes allow fabrication of three-dimensional complex parts. Due to the exact amount of material used during the manufacturing step, these new manufacturing processes...

Friction Stir Welding of Non-Heat-Treatable High-Strength Alloy 5083-O

Abstract: 5083 aluminum alloy is increasingly used because of its excellent corrosion resistance, high work-hardening rate, and strength. In order to improve its weldability and feasibility, material behavior, material flow, and defects induced while friction stir welding 5083 should be studied. In this study, they were investigated by thermo-structural analysis. The flow stress of 5083-O has a high rate of sensitivity among high temperatures and wide strain rate ranges. Therefore, the details of the mechanical properties of 5083-O at high temperatures and wide strain rate ranges were investigated to obtain reasonable analysis results using a precise flow stress model. The tool/workpiece interface temperature during FSW is critical for accurate analysis results. This study used special equipment to measure tool temperature in order to investigate the interface temperatures precisely, and then the obtained data were used for optimization and verification of the thermal boundary conditions for analysis modeling. Using the developed model, the material behavior and material flow during FSW of 5083-O were analyzed. The tool and workpiece interface temperatures, flow stresses, strain rates, and velocities were investigated with the cylinder and threaded probes in detail. One of the analysis results indicated that the material flow rate on the rear side of a probe directly affected defect generation while joining.

Effect of Processing Parameters on Plastic Flow and Defect Formation in Friction-Stir-Welded Aluminum Alloy

Abstract: The effect of processing parameters on material flow and defect formation during friction stir welding (FSW) was investigated on 6.0-mm-thick 2014Al-T6 rolled plates with an artificially thickened oxide layer on the butt surface as the marker material. It was found that the “S” line in the stir zone (SZ) rotated with the pin and stayed on the retreating side (RS) and advancing side (AS) at low and high heat inputs, respectively. When the tool rotation rate was extremely low, the oxide layer under the pin moved to the RS first and then to the AS perpendicular to the welding direction, rather than rotating with the pin. The material flow was driven by the shear stresses produced by the forces at the pin–workpiece interface. With increases of the rotation rate, the depth of the shoulder-affected zone (SAZ) first decreased and then increased due to the decreasing shoulder friction force and increasing heat input. Insufficient material flow appeared in the whole of the SZ at low rotation rates and in the bottom of the SZ at high rotation rates, resulting in the formation of the “S” line. The extremely inadequate material flow is the reason for the lack of penetration and the kissing bonds in the bottom of the SZ at extremely low and low rotation rates, respectively.

An approach to develop hansel-spittel constitutive equation during ingot breakdown operation of low alloy steels

Abstract: The control of the final quality of a forged product requires an in-depth comprehension of quality of the initial casted ingot. Hot workability is an important property which can be evaluated by variation of strain, strain rate, and temperature. Modeling of forging process always needs to define constitutive models for the material involved. In this study, 42CrMo steel with dendritic microstructure was used to generate the flow stress curves. In order to provide accurate predictions of the thermal and mechanical parameters in the actual ingot break down operation, hot compression tests were carried out at uniform temperatures ranging from 1050 to 1200 °C and strain rates of 0.25–2 s−1. Finally, Hansel–Spittel law was developed to represent the dependency of the material flow stress on strain, strain rate, and temperature. FE Simulation results reveal that the model is able to predict the adiabatic heating during deformation.

A system dynamics model of financial flow in supply chains: a case study

Abstract: The article discusses the operational and financial relationships among the channel members of a supply chain comprising of a manufacturing company and a distributor. This research simulates the financial system that enables a more accurate diagnosis of disaggregated metrics “Cash to Cash”, considering different interactions between material flow and the financial flow of the two links, manufacturer and distributor. This model considers the feedback loops between material flow models and financial models without which some interactions are lost during simulation. The proposed diagnostic method which incorporates an eclectic process re-engineering practices and state of the art of dynamic simulation with the implementation of advanced techniques of sensitivity and dynamic optimization models those are applied on the concept of stocks and flows. This methodology is used in order to analyze and improve business strategies by generating policies which help to improve cash flow of the company. To validate our model, a case study illustrating the improvement of different metrics of the supply chain is considered here. The results show that the companies have to invest in technology in order to generated strategic decision to enhance their financial metrics.

Optimization for China’s coal flow based on matching supply and demand sides

Abstract: As the most significant material flow in China, coal resource flow has many problems, including unnecessary CO2 emission and energy waste. The national coal flow consists of coal moving between mines and demand enterprises. The approach to global coal flow optimization can be transformed to promote a scientific match between participant enterprises. To reach this goal, the concept of matching dependencies on coal utilization by classification and gradation was introduced. A two-sided matching method was adopted to develop an optimization model based on an appropriate index system consisting of coal type, coal quality, transport conditions, and other factors. Based on inherent differences, indexes were divided into a 0–1 feature information index, an interval number information index and a language evaluation index. After data collection and screening, a sample of 2206 production nodes and 1500 consumption nodes was evaluated. Furthermore, a scenario with the goal of minimizing the global turnover volume was compared. The results showed that in the matching scenario, approximately 10% of the ash content at the national level avoided long-distance transportation and 170 million tons of anthracite and main coking coal were reallocated from power generation to more appropriate industries. Additionally, the optimization model may also significantly reduce CO2 emissions caused by ash during transportation. On the bases of these results, some suggestions focusing on the participants of each link are proposed in the final section of this paper. Overall, the application of the matching model can be a potential solution to optimize China’s future coal flow.

Usulan Perbaikan Tata Letak Fasilitas Terhadap Optimalisasi Jarak dan Ongkos Material Handling Dengan Pendekatan Systematic layout planning (SLP) di PT Transplant Indonesia

Abstract: – Unplanned layout and inefficient material flow between work units can lead to increased cost. PT Transplan Indonesia's current material flow path is inefficient with material flow distance 115.5 meters and material handling cost that has not been taken into account. This study aims to find out how big the role of facility layout design in cutting the distance of material transfer and pressing the cost of material handling. The method used in this research is Systematic Layout Planning (SLP) approach, which is comparing the distance of material transfer between initial layout with proposed layout. The results of this study indicate that the distance of the material flow path on the production floor with proposed layout changed to 71,7 meters, with material handling cost per meter reduced from Rp. 1,105,954 to Rp. 712,402 or decrease as much as 35%. Based on the results of the research, the layout of the proposal is considered more effective and efficient because it can reduce the distance of material transfer and reduce the cost of material handling on the packing/shipping floor. Keywords: Layout Design; Material handling cost; Systematic Layout Planning (SLP)