Showing papers on "Material flow published in 2020"

Plastics in the US: toward a material flow characterization of production, markets and end of life

Abstract: Managing plastics has become a focal issue of the Anthropocene. Developments in plastic materials have made possible many of the technologies and conveniences that define our modern life. Yet, plastics are accumulating in landfills and natural environments, impacting resource utilization and ecosystem function. Solutions to these rising problems will require action and coordination across all stages of plastics value chains. Here, we offer the first contemporary plastics material flow by resin type through the US economy, encompassing 2017 production, sales, use markets and end-of-life management. This roadmap, while sourced from disparate and incomplete data, provides stakeholders with a system-scale context for understanding challenges, opportunities and implications of future interventions. More than three-quarters of the plastics reaching end of life went to landfill, and less than 8% was recycled. Packaging was the largest defined use market for plastics, but two thirds of the plastic put into use in 2017 went into other markets, including consumer products, electronics, buildings and transportation. In nearly all uses, increased coordination between material and product innovation and design and end-of-life recovery and recycling are needed. Alignment of technology, policy and market drivers will be necessary to reduce plastic waste and improve the circularity of plastic materials. Abbreviation definitions LDPE low-density polyethylene LLDPE linear low-density polyethylene HDPE high-density polyethylene PP polypropylene PS polystyrene EPS expandable polystyrene PVC polyvinyl chloride PET polyethylene terephthalate ABS acrylonitrile-butadiene-styrene ASR auto-shredder residue ACC American Chemistry Council Mt Megatonnes=million metric tonnes US United States of America US EPA United States Environmental Protection Agency PCB polychlorinated biphenyl MSW municipal solid waste C&D construction and demolition EOL end-of-life PUR polyurethanes

Defect formation and material flow in Friction Stir Welding

Abstract: This work addresses the issue of the simulation and prediction of defect formation through the analysis of the material mixing during Friction Stir Welding (FSW). A coupled thermomechanical model is used for the FSW simulation. To follow the flow of the material, a tracing technique of the material particles is incorporated in the numerical model. A fast and accurate two-stage numerical strategy is adopted to analyse the FSW process. The speed-up stage intends to reach the steady state quickly. The material tracing is performed in the periodic stage where the rotation of the tool is modelled. The effect of the process parameters and the pin features on the defect formation is studied. The model is capable of predicting defects such as void, wormhole, flash and joint line remnant, as well as the formation of “onion rings” in a single simulation. The results show that the proposed model has significant capability to explain and predict the post-FSW defects.

Modeling and experimental validation of material flow during FSW of polycarbonate

Abstract: Friction stir welding (FSW) of thermoplastic materials is an attractive but a challenging process due to inherent chemical and mechanical characteristics of polymeric materials. In the present work, thermo-mechanical models were employed to investigate the effect of processing parameters on of FSW of polycarbonate (PC). The heat flux during the joining process was localized around the PC join line and led to the formation of circular rings on the upper surface. According to the simulation results, increasing the tool rotational velocity reduced the temperature gradient and decfeased the suseptibelity of crack formation around the joint line. Cracks were formed at low frictional heats and high strain rates during material stirring. On the other hand, higher heat inputs increased the volume of the preheated material in front of the FSW tool and extruded the material from the leading edge into leading edge. Consequently, less crackes were formed as the plasticized material filed SZ. The results can be used to establish more robust processing parameters for FSW of polymers.

Using look-ahead plans to improve material flow processes on construction projects when using BIM and RFID technologies

Abstract: Building information modelling (BIM) and radio frequency identification (RFID) technologies have been extensively explored to improve supply chain visibility and coordination of material flow processes, particularly in the pursuit of Industry 4.0. It remains challenging, however, to effectively use these technologies to enable the precise and reliable coordination of material flow processes. This paper aims to propose a new workflow designed to include the use of detailed look-ahead plans when using BIM and RFID technologies, which can accurately track and match both the dynamic site needs and supply status of materials.,The new workflow is designed according to lean theory and is modeled using business process modeling notation. To digitally support the workflow, an integrated BIM-RFID database system is constructed that links information on material demands with look-ahead plans. The new workflow is then used to manage material flows in the erection of an office building with prefabricated columns. The performance of the new workflow is compared with that of a traditional workflow, using discrete event simulations. The input for the simulations was derived from expert opinion in semi-structured interviews.,The new workflow enables contractors to better observe on-site status and differences between the actual and planned material requirements, as well as to alert suppliers if necessary. The simulation results indicate that the new workflow has the potential to reduce the duration of the material flow processes by 16.1% compared with the traditional workflow.,The new workflow is illustrated using a real-world-like situation with input data based on expert opinion. Although the workflow shows potential, it should be tested on a real-world site.,The new workflow allows project participants to combine detailed near-term look-ahead plans with BIM and RFID technologies to better manage material flow processes. It is particularly useful for the management of engineer-to-order components considering the dynamic site progress.,The research improves on existing research focused on using BIM and RFID technologies to improve material flow processes by showing how the workflow can be adapted to use detailed look-ahead plans. It reinforces data-driven construction material management practices through improved visibility and reliability in planning and control of material flow processes.

Modelling and parameter optimization for filament deformation in 3D cementitious material printing using support vector machine

Abstract: The material flow mechanism affects the printing quality considerably in 3D cementitious material printing (3DCMP) area. A numerical model was developed to investigate the material flow mechanism during the extrusion and deposition process. To quantify the effects of flow mechanism on the filament printing quality, deformation of the printed filament was proposed. Then a Support Vector Machine (SVM) was employed to study various factors on flow mechanism, hence the deformation of the printed filament. The SVM model results showed that deformation of the printed filament is independent of plastic viscosity, however, material yield stress and relative nozzle travel speed significantly affect the deformation of the printed filament. Lastly, an empirical parametric associative model was proposed to predict the filament deformation based on material yield stress and relative nozzle travel speed.

Investigation on the material flow and deformation behavior during ultrasonic-assisted incremental forming of straight grooves

Abstract: The introduction of ultrasonic vibration is proved to be beneficial for the reduced force and improved formability for sheet forming processes. However, the vibration-induced material behavior is still not satisfactorily explained. The objective of this work is to investigate the effect of the ultrasonic vibration on the material flow characteristics and the plastic deformation mechanism during the incremental sheet forming of the straight groove. Both analytical and finite element models are established to explore the impacts of ultrasonic amplitude, frequency, step-down size and feed rate on material flow characteristics. It was found that the material flow area was dramatically increased after applying the ultrasonic vibration, and the influence of ultrasonic amplitude on material flow area is greater than that of frequency, which is similar to the effect of acoustic softening. In addition, the separation effect under different amplitudes and frequencies was analyzed through finite element modeling to partly explain the reduction of forming forces. The duty cycle was decreased as the amplitude increases as well as the frequency. Furthermore, the material flow behavior and the force reduction rate for different tool paths are explored. Finally, experiments were performed which further verified the reliability of the analytical and FE models. These findings provide a theoretical basis for further investigation of the mechanisms of ultrasonic-assisted incremental sheet forming process.

Robust boundary flow in chiral active fluid.

Abstract: We perform experiments on an active chiral fluid system of self-spinning rotors in a confining boundary. Along the boundary, actively rotating rotors collectively drive a unidirectional material flow. We systematically vary rotor density and boundary shape; boundary flow robustly emerges under all conditions. Flow strength initially increases then decreases with rotor density (quantified by area fraction ϕ); peak strength appears around a density ϕ=0.65. Boundary curvature plays an important role: flow near a concave boundary is stronger than that near a flat or convex boundary in the same confinements. Our experimental results in all cases can be reproduced by a continuum theory with single free fitting parameter, which describes the frictional property of the boundary. Our results support the idea that boundary flow in active chiral fluid is topologically protected; such robust flow can be used to develop materials with novel functions.

Rotation nozzle and numerical simulation of mass distribution at corners in 3D cementitious material printing

Abstract: When conducting corner printing with rotational rectangular nozzle, a greater amount of material is deposited inside the filament and hence tearing and skewing will occur on the surface of the printed filament. With the aim of maintaining the surface finish and mechanical properties of the printed filament, a 3D numerical model is developed to study the flow mechanism at a corner under various conditions during the extrusion and deposition processes with rotational nozzle. After experimental validation, the numerical model is employed to study the material flow mechanism under various conditions. The results indicate that the rheological properties have little effect on the mass distribution ratio. However, a high relative nozzle travel speed, larger corner radii and lower nozzle aspect ratio is a promising route in obtaining a uniform material distribution ratio. The interlinking of process parameters affects the material distribution ratio significantly as well. Furthermore, the importance of the factors that affect the mass distribution was determined quantitatively.

Optimization of Distributed Integrated Multi-energy System Considering Industrial Process Based on Energy Hub

Abstract: As a typical scenario of distributed integrated multi-energy system (DIMS), industrial park contains complex production constraints and strong associations between industrial productions and energy demands. The industrial production process (IPP) consists of controllable subtasks and strict timing constraints. Taking IPP as a control variable of optimal scheduling, it is an available approach that models the IPP as material flow into an extension energy hub (EH) to achieve the optimization of industrial park. In this paper, considering the coupling between the production process and energy demands, a model of IPP is proposed by dividing the process into different adjustable steps, including continuous subtask, discrete subtask, and storage subtask. Then, a transport model of material flow is used to describe the IPP in an industrial park DIMS. Based on the concept of EH, a universal extension EH model is proposed considering the coupling among electricity, heat, cooling, and material. Furthermore, an optimal scheduling method for industrial park DIMS is proposed to improve the energy efficiency and operation economy. Finally, a case study of a typical battery factory is shown to illustrate the proposed method. The simulation results demonstrate that such a method reduces the operation cost and accurately reflects the operation state of the industrial factory.

Experimental and theoretical analysis of the thickness distribution in multistage two point incremental sheet forming

Abstract: Incremental sheet forming (ISF) has received increasing attention with its advantages of economy and flexibility for small batch sheet metal parts. However, the excessive thinning may be resulted at large forming angles for complex parts, which cannot meet the design requirements and seriously impedes the industrial application of ISF. Although the multistage incremental sheet forming (MISF) has been proposed to overcome the dilemma of excessive thinning in ISF, the design of the optimal strategy which can control material flow and improve thickness distribution is a critical issue. In this paper, three promising multistage two point incremental sheet forming (MTPIF) path strategies, i.e., parallel line strategy, variable angle strategy, and stretch-bend-assisted strategy, are selected to investigate the influence of tool paths on thickness distributions, material flow, and geometric error. Firstly, experimental thickness distributions of truncated pyramids formed with three path strategies and single-stage TPIF strategy are compared. Meanwhile, the theoretical models are introduced to illustrate the difference of thickness distributions both at the wall and the corner. Compared with single-stage TPIF strategy, MTPIF path strategies studied in this paper are effective to improve the thickness distribution of truncated pyramids at both the component wall and the corner. Through the theoretical analysis, it is found that the thickness distribution at the wall can be controlled by adjusting intermediate forming angles. Meanwhile, the intermediate shape in circumferential direction has significant influence on the thickness distribution for complex parts. Then, the material flows of three path strategies at different forming stages are analyzed. It is found that the materials at the flange as well as transition arcs are deformed into wall to increase the thickness distribution. Finally, considering both thickness distributions and geometric errors, the variable angle strategy is found as the effective MTPIF strategy for the studied process.

Field generated nematic microflows via backflow mechanism.

Abstract: Generation of flow is an important aspect in microfluidic applications and generally relies on external pumps or embedded moving mechanical parts which pose distinct limitations and protocols on the use of microfluidic systems. A possible approach to avoid moving mechanical parts is to generate flow by changing some selected property or structure of the fluid. In fluids with internal orientational order such as nematic liquid crystals, this process of flow generation is known as the backflow effect. In this article, we demonstrate the contact-free generation of microfluidic material flows in nematic fluids -including directed contact-free pumping- by external electric and optical fields based on the dynamic backflow coupling between nematic order and material flow. Using numerical modelling, we design efficient shaping and driving of the backflow-generated material flow using spatial profiles and time modulations of electric fields with oscillating amplitude, rotating electric fields and optical fields. Particularly, we demonstrate how such periodic external fields generate efficient net average nematic flows through a microfluidic channel, that avoid usual invariance under time-reversal limitations. We show that a laser beam with rotating linear polarization can create a vortex-like flow structure and can act as a local flow pump without moving mechanical parts. The work could be used for advanced microfluidic applications, possibly by creating custom microfluidic pathways without predefined channels based on the adaptivity of an optical set-up, with a far reaching unconventional idea to realize channel-less microfluidics.

Analysing material and embodied environmental flows of an Australian university — Towards a more circular economy

Abstract: Humans are extracting and consuming unprecedented quantities of materials from the crust of the Earth. Contributing to this consumption, university campuses require large amounts of materials to operate. This offers opportunities for the implementation of circular economy principles that optimise material use and demonstrate best practice to future generations of decision makers, globally. This paper uses the Parkville campus of the University of Melbourne as a single revelatory case study to quantify its material flow for 2017. We use extremely disaggregated procurement data of 11 555 purchases of materials, mapped against 189 different material archetypes to estimate material inflows. Material outflows are sourced directly from the waste management contractor of the University. We also quantify the embodied energy, water, and greenhouse gas emissions of all inflows, using environmentally extended input-output analysis. Results show that procurement-related inflows tend to represent a small share (∼4%) of the total material flows (2 280 Gg), but result in significant environmental effects due to the nature of the materials (e.g. electronics, cabling, photovoltaic panels, furniture, etc.). The modelled procurement-related purchases result in 22 587 GJ of energy, 1 477 GgCO2e of greenhouse gas emissions and 30 891 kL of water, and 3.46 MAUD in cost, annually. Yet, the majority of material flows on campus tend to be generated by non-procurement-related drivers, notably food and food packaging waste resulting from retail on and off campus. Based on these findings, the paper recommends a series of actions that universities and large organisations can adopt to transition to a more circular economy.

Material Flow Optimization through E-Kanban System Simulation

Abstract: The digital evolution of lean thinking increases visibility along the whole value chain. It spreads and intensifies the potential of Supply Chain Collaboration in the network through the digitalization of orders, tracking deliveries and supplies in real-time, optimizing material and informational flows, and streamlining delivery time. Industry 4.0 transforms the business by creating a favourable environment for implementing well-known technologies from JIT/JIS and Kanban. The article aimed to map and create a simulation model of the production-assembly process and to propose the introduction of Kanban logic into material flow control. The implementation of the Kanban system and the testing of variant solutions using the simulation software Tecnomatix Plant Simulation made it possible to find the optimal solution. (Received in February 2020, accepted in May 2020. This paper was with the authors 1 week for 1 revision.)

Energy Consumption Analysis for Vehicle Production through a Material Flow Approach

Abstract: The aim of this study is to comprehensively evaluate the energy consumption in the automotive industry, clarifying the effect of its productive processes. For this propose, the material flow of the vehicles has been elaborated, from mining to vehicle assembly. Initially, processes where each type of material was used, and the relationship between them, were clarified. Subsequently, material flow was elaborated, while considering materials input in each process. Consequently, the consumption of energy resources (i.e., oil, natural gas, coal, and electricity) was calculated. Open data were utilized, and the effects on the Japanese vehicle market were analyzed as a case study. Our results indicate that the energy that is required for vehicle production is 41.8 MJ/kg per vehicle, where mining and material production processes represent 68% of the total consumption. Moreover, 5.23 kg of raw materials and energy resources are required to produce 1 kg of vehicle. Finally, this study proposed values of energy consumption per mass of part produced, which can be used to facilitate future material and energy analysis for the automotive industry. Those values can be adopted and modified as necessary, allowing for possible changes in future premises to be incorporated.

Monitoring Sustainability Effects of the Bioeconomy: A Material Flow Based Approach Using the Example of Softwood Lumber and Its Core Product Epal 1 Pallet

Abstract: The transition of our current economic system towards a bioeconomy that is based on renewable materials and energy can be an important contribution but at the same time a threat to mitigate the challenges of the 21st century, such as global warming and resource depletion. To assess societal, economic, and environmental impacts associated with this transition, we propose an approach for a sustainability assessment as an integral part of a future bioeconomy monitoring concept. The assessment approach is based on material flow analyses of the bioeconomy and their core products. As a proof of applicability, the proposed assessment approach is exemplified for the material flow of softwood lumber and its core product ‘EPAL 1 pallet’. To simulate a frequent monitoring, material flow analysis and assessment of six sustainability effects are applied for the years 2010 and 2015. Since a frequent bioeconomy monitoring requires regularly updated and quality assured data, official statistics should be the major source of information. Whereas cutoff thresholds, nondisclosure of data, and high level of aggregation are major limitations of official production statistics and for material flow analysis, lack of information regarding environmental effects is the major limitation for material flow related sustainability assessment. We make suggestions on how to overcome these limitations and put our approach in to context with other ongoing monitoring activities.

CFD Modelling of Temperature Distribution and Material Flow Investigation During FSW of DH36 Shipbuilding Grade Steel

Abstract: A modified heat transfer and material transfer model was investigated for friction stir welding of DH36 steel by considering the Eulerian framework in steady state. During this analysis, temperature-dependent properties of the workpiece and the tool material were used. The material viscosity was modelled as a non-Newtonian viscoplastic fluid depending on the temperature and flow stress. The heat generation at the tool workpiece interface incorporated the partial sticking and partial sliding condition. An asymmetric and skewed temperature distribution at the advancing trailing side was observed. Asymmetry of temperature distribution was increased with an increase in the tool traverse speed. It was observed that the temperature was maximum at the interface between the shoulder and tool, and the peak temperatures decreased non-uniformly along the thickness direction. The results of material flow analysis indicated that the hot plasticized material flew ahead the tool along the retreating side in counter-clockwise direction, passed the tool and got released behind the tool during the welding stage. There existed a swirl region on the advancing side which was highly prone to defect formation. The temperature field and plastic flow field of the computational model matched satisfactorily with the experiment results.

Optimizing Resources of Multimodal Transport Terminal for Material Flow Service

Abstract: Multimodal transport terminals are the elements of transport systems that ensure the interaction of enterprises of various modes of transport. The effective functioning of transport terminals significantly affects the efficiency of the material flow servicing in a supply chain and the sustainability of the whole transport system. The paper proposes an approach to determine the optimal parameters of production resources in multimodal transport terminals, based on numerical computer simulations of technological operations in a transport terminal for the given parameters of incoming and outgoing material flows. The practical use of the proposed approach is shown on the example of the Amur Harbor cargo area of the Dnipro River Port.

Exploration of the material transfer effect in local loading forming of ultra-large-size integrated component with multi-rib

Abstract: Isothermal local loading forming is a less-loading and flexible forging technology, which is promising to form the ultra-large-size integrated component with multi-rib by adopting small tonnage equipment. Due to the local loading characteristic, the material in the loading region can transfer into the unloading region in the transitional region. Identifying the affect region of the material transfer is important to control the material flow and obtain high-quality components under local loading way. In this work, the phenomena of the material transfer are explored and the boundaries of the transitional region are clarified. Firstly, the material transfer after each loading step is analyzed by displacement field and strain field based on finite element simulation of the ultra-large component. Meanwhile, the velocity vectors during each loading step are observed. Secondly, the variations of the material volume in different loading zones during each loading step are revealed. Subsequently, the change of material volume located far from the die partition line is analyzed. Furthermore, the induced forming problems by the material transfer effect, i.e., folding and additional strain, are elaborated. Finally, the boundaries between the transitional region and first/second loading zone are determined. The phenomena of the material transfer and the induced folding in the transitional region are verified using an eigenstructure with multi-rib by the FE simulation and physical simulation experiment.

Effect of Heating Time on Thermomechanical Behavior of Friction-Welded A105 Bar to A312 Pipe Joints

Abstract: The dissimilar materials of pipe component was produced between A105 forged steel and A312 stainless steel. In order to determine the superiority of the friction-welded component, its thermomechanical behavior was studied. In situ observations and finite elemental analysis recorded the difference in the thermal distribution of the pipe components. The high-speed camera observations revealed a large amount of material flow in stainless steel during welding. The temperature and amount of material flow increased with the increase in heating time. The finite elemental modeling exhibited the presence of maximum temperature at the periphery of the joint. The distribution of heat flow on stainless steel was uniform, while it slowly increased from periphery to the center of the joint for forged steel. The required amount of temperature was obtained at a heating time of 6 s and distributed evenly throughout the joint. Finite elemental modeling and experimental analysis confirmed the growth of temperature at the joint interface as heating time increased.

A Novel Closed-Loop Supply Chain Network Design Considering Enterprise Profit and Service Level

Abstract: Increasing concerns for sustainable development have motivated the study of closed-loop supply chain network design from a multidimensional perspective. To cope with such issues, this paper presents a general closed-loop supply chain network comprising various recovery options and further formulates a multi-objective mixed-integer linear programming model considering enterprise profit and service level simultaneously. Within this model, market segmentation is also considered to meet real-world operating conditions. Moreover, an e -constraint method and two interactive fuzzy approaches are applied to find a global optimum for this model together with the decisions on the numbers, locations, and capacities of the facilities, as well as the material flow through the network. Ultimately, numerical experiments are conducted to demonstrate the viability and effectiveness of both the proposed model and solution approaches.

Material flow during friction hydro-pillar processing

Abstract: Friction hydro-pillar processing (FHPP) is a novel technique that involves solid-state joining of an external plug onto a substrate by plastic deformation. A systematic investigation on material fl...