Fused Deposition Modelling (FDM) is an additive manufacturing (AM) process that produces a physical object directly from a CAD design using layer-by-layer deposition of the filament material that is extruded via a nozzle. In industry, FDM has become one of the most used AM processes for the production of low batch quantity and functional prototypes, due to its safety, efficiency, reliability, low cost, and ability to process manufacturing-grade engineering thermoplastic. Recently, the market is flooded with the availability of low-cost printers produced by numerous companies. This research aims to investigate the effect of different porosity levels on a scaffold structure produced using a low-cost 3D printer. Comparisons of these porous structures were made in terms of Von-Mises strain, total deformation, as well as compressive stress. Various porosity levels were created by varying printing parameters, including layer height, infill density, and shell thickness by slicing the initial solid CAD file using Repetier Host 3D printing software. Finite Element Analysis (FEA) simulation was then performed on the created scaffold structures by using Ansys Workbench 19.2. The simulation result indicates that the greater porosity level will result in higher total deformation of the structure. Meanwhile, the compression test shows that the minimum strength value obtained was favourable at 22 MPa and had exceeded that of the trabecular femur (15 MPa). However, its porosity level (maximum at 52%) was still below that of the minimum threshold of porosity level of 70 percent. However, the printing parameters currently used can be adjusted in the future. Therefore, it was deduced that the low-cost 3D printer offers promising potential to fabricate different porosity structures with multiple outcomes.

As one of the preoperative diagnostic methods, needle insertion is widely used for its safety and effectiveness. Recently, robotic needle insertion systems have been under active developments. Hence needle insertion experiments are essential for system verifications, in which the interactions between needle and tissue is a major focus for needle-tissue interactive models, and the friction between the needle and tissue is an important factor. In these experiments, the friction coefficient can be affected by many factors, such as insertion speed, needle-tissue deformation and contact forces. In this paper, to study and analyze the influence of various variables on friction force and friction coefficient, three variables, i.e., tissue pressure on needle, needle insertion velocity and Young’s modulus of the tissue, are systematically studied by constructing a testbed, in which the radial surface friction is converted into equivalent plane friction based on the assumption that the distribution of the normal force and friction force on the needle is uniform for the whole needle outer surface. The experimental results show that the variation range of friction coefficient is 0.122–0.341. The friction coefficient decreases with the increase of pressure and increases with the increase of velocity, while Young’s modulus have a small effect on the friction coefficient.

The process mechanics phenomena play an important role in all metal cutting processes. Conditions are changing progressively not only to high velocities and deformation, but also to the interfacial friction between two different materials — tool and workpiece, and inside the same material, as a result of material flow with high temperatures. It will be shown, that during the ploughing effect in the interface between tool and chips there are two different kinds of friction, external and internal friction. All the existent models ignore this reality. Therefore, an alternative must be found to model the real phenomena during metal plastic flow in a more appropriate manner. In this study, we will consider the cutting process in fundamental terms based only on mathematics and physics. In connection with this fundamental development a question arises, “Which parameters are the best for characterizing the cutting process and can the equations be proven after processing, because nearly each parameter will disappear, such as stress, strain, friction or temperatures etc.”? It might be that only the plastic material deformation in connection with the external and internal friction can be identified and visualized after the cutting process for comparing the developed theoretical result with the experimental result of the chip formation region. That leads to the fact that, as long as agreement between theoretical and experimental result can be demonstrated, there is evidence that stress and strain, as well as friction and temperatures are correctly estimated. Therefore, this paper is focused on the plastic deformation ds in the plastic region during the cutting process. This plastic deformation will be expressed for the non-stationary, dynamic cutting process with non-uniform feed (toolworkpiece contact evolving from rubbing to material separation) and chip flow. This process behavior is relevant for the milling operation of metals as well as for carbon composites with glass fibers. For carbon composites with glass fibers, additional environmental and human safety aspects will arise, as described in this paper.

To enable safe and effective human-robot collaboration (HRC) in smart manufacturing, seamless integration of sensing, cognition and prediction into the robot controller is critical for real-time awareness, response and communication inside a heterogeneous environment (robots, humans, equipment). The specific research objective is to provide the robot Proactive Adaptive Collaboration Intelligence (PACI) and switching logic within its control architecture in order to give the robot the ability to optimally and dynamically adapt its motions, given a priori knowledge and predefined execution plans for its assigned tasks. The challenge lies in augmenting the robot’s decision-making process to have greater situation awareness and to yield smart robot behaviors/reactions when subject to different levels of human-robot interaction, while maintaining safety and production efficiency. Robot reactive behaviors were achieved via cost function-based switching logic activating the best suited high-level controller. The PACI’s underlying segmentation and switching logic framework is demonstrated to yield a high degree of modularity and flexibility. The performance of the developed control structure subjected to different levels of human-robot interactions was validated in a simulated environment. Open-loop commands were sent to the physical e.DO robot to demonstrate how the proposed framework would behave in a real application.

The next generation of the manufacturing industry calls for new approaches with smarter functionalities and better/safer working environment for human beings. The Human-Robot Collaboration (HRC) approach provides a feasible solution combing the flexibility and intelligence of a human, together with the accuracy and strength of an industrial robot. However, in the past years, despite the significant development of different HRC approaches, there is still a lack of clear safety strategy for an HRC system. Thus in this paper, the extensive taxonomy of the human-robot relations are first defined to provide a clear classification in different robotic scenarios. Then a comprehensive action strategy is developed toward different scenarios and human stakeholder’s roles. A dynamic HRC layout approach is also introduced based on the actual speed of human and robot and the distance between them. The feasibility of the proposed approaches in this paper is then evaluated via the implemenntation in an HRC-based assembly cell. The operator’s biometric data is also included in the HRC control loop. It is proven achievable to conduct personalised HRC safety strategy based on the human stakeholder’s role, physical conditions, speed and so forth. The future research outlooks and essential considerations are addressed at the end of the paper.

Additive manufacturing (AM) has had an enormous impact in the manufacturing sector. Its role has evolved from printing prototypes to manufacturing functional parts for a variety of applications in the automotive, aerospace, and medical industries. Recently, AM processes have also been applied in the infrastructure construction industry. Applications of AM processes could bring in significant improvements in infrastructure construction, specifically in the areas of productivity and safety. It is desirable to have a review on the current state of emerging AM processes for infrastructure construction as well as existing gaps in this field. This paper reviews AM processes in infrastructure construction. It discusses the process principle, application examples, and gaps for each of the AM processes.

Single point incremental forming (SPIF) is more accurate and economical than the conventional forming process for customized products. Majority of the work in SPIF has been carried out on metals. However, polymers are also required to shape. Polycarbonate has wide application in safety glass, bottles, automotive and aircraft industry due to its transparent as well as attractive processing and mechanical properties as compared to other polymeric plastics. In present work, the Polycarbonate (PC) sheet of thickness 1.8 mm is deformed to make a square cup at different angles. Tensile testing is done to analyze the effect of wall angle on the deformed cup. This work illustrates the effect of the SPIF process on material strength in a different directions (vertical and horizontal) of the final deformed product. Tool forces are evaluated using ABAQUS ® simulation for SPIF. Numerical simulation approach is used to calculate the fracture energy, which utilizes the force-displacement curve of the specimen and is verified.

Machining operations such as reaming, boring or milling create undesirable extruded sharp edges at the entry and exit side of the machined holes. These sharp burrs / extruded edges act as stress concentration regions for fatigue crack propagation in safety critical aerospace components. In this paper, results of an experimental investigation carried out on surface integrity of titanium based alloy during mechanized edge profiling process are presented. In the Mechanized Edge Profiling (MEP) process the primary sharp edges created as result of hole machining are removed using a hard point countersink tool and the secondary sharp edges produced due to countersinking/chamfering the hole entry and exit side edges are radiused using nylon impregnated silicon carbide brushes. On-machine edge profiling experiments were conducted using compliant Flexhone™ and Novoflex™ globular abrasive brushes on highly stressed bolt/flange holes. Brushing speed and feed rate were identified as key process variables. Nylon impregnated with silicon carbide 320 grit brush showed good performance when brushing at a speed of 5000rpm and 5000mm/min feed rate which produced a very consistent and controlled secondary edge radius of 0.3±0.2mm up to 30 holes. An acceptable surface roughness (Ra) of less than 0.5μm on the chamfer and bore surfaces were achieved.

In recent years, Cloud manufacturing has become a new research trend in manufacturing systems leading to the next generation of production paradigm. However, the interoperability issue still requires more research due to the heterogeneous environment caused by multiple Cloud services and applications developed in different platforms and languages. Therefore, this research aims to combat the interoperability issue in Cloud Manufacturing System. During implementation, the industrial users, especially Small- and Medium-sized Enterprises (SMEs), are normally short of budget for hardware and software investment due to financial stresses, but they are facing multiple challenges required by customers at the same time including security requirements, safety regulations. Therefore in this research work, the proposed Cloud manufacturing system is specifically tailored for SMEs.

Micro-milling tool breakage has become a bottleneck for the development of micro-milling technology. A new method to predict micro-milling tool breakage based on theoretical model is presented in this paper. Based on the previously built micro-milling force model, the bending stress of the micro-milling cutter caused by the distributed load along the spiral cutting edge is calculated; Then, the ultimate stress of carbide micro-milling tool is obtained by experiments; Finally, the bending stress at the dangerous part of the micro-milling tool is compared with the ultimate stress. Tool breakage curves are drawn with feed per tooth and axial cutting depth as horizontal and vertical axes respectively. The area above the curve is the tool breakage zone, and the area below the curve is the safety zone. The research provides a new method for the prediction of micro-milling tool breakage, and therefore guides the cutting parameters selection in micro-milling.

With the increasing demands in the automotive industry for passenger safety and higher structural strength and stiffness, the automotive industry is using more advanced high strength steels. The ability to reduce tool wear and drilling forces in post forming drilling of high strength steel parts is of high importance to the automotive industry. Electrically assisted drilling is a process in which electric current is passed through the drill bit to the workpiece resulting in local softening, and allowing for a reduction in cutting forces and potential increase in tool life. In this paper, tungsten carbide (WC)-tipped drill bits are used to study the effect of varying electrical current on 1500 Usibor ® steel work pieces. The effects of current on the drilling process of high strength steel are investigated in this research by studying the maximum temperature during drilling, the dependence of chip formation, tool wear and the axial force during the drilling operation. It was found that the magnitude of current passed through the workpiece directly influences the axial force that the tool experiences, and thus the tool wear. This effect is modeled through Joule heating, leading to elevated temperature and thermal softening.

As American vehicle fuel efficiency requirements have become more stringent due to the CAFE standards, the auto industry has turned to fiber reinforced polymer composites as replacements for metal parts to reduce weight while simultaneously maintaining established safety standards. Furthermore, these composites may be easily processed using established techniques such as injection molding and compression molding. The mechanical properties of these composites are dependent on, among other variables, the orientation of the fibers within the part. Several models have been proposed to correlate fiber orientation with the kinematics of the polymer matrix during processing, each using various strategies to account for fiber interactions and fiber flexing. However, these all require the use of empirical fitting parameters. Previous work has obtained these parameters by fitting to orientation data at a specific location in an injection-molded part. This ties the parameters to the specific mold design used. Obtaining empirical parameters is not a trivial undertaking and adds significant time to the entire mold design process. Considering that new parameters must be obtained any time some aspect of the part or mold is changed, an alternative technique that obtains model parameters independent of the mold design could be advantageous. This paper continues work looking to obtain empirical parameters from rheological tests. During processing, the fiberpolymer suspension is subjected to a complex flow with both shear and extensional behavior. Rather than use a complex flow, this study seeks to isolate and compare the effects of shear and extension on two orientation models. To this end, simple shear and planar extension are employed and the evolution of orientation from a planar random initial condition is tracked as a function of strain. Simple shear was imparted using a sliding plate rheometer designed and fabricated in-house. A novel rheometer tool was developed and fabricated in-house to impart planar extension using a lubricated squeeze flow technique, where a low viscosity Newtonian lubricant is applied to the solid boundaries to minimize the effect of shearing due to the no-slip boundary condition. The Folgar-Tucker model with a strain reduction factor is used as a rigid fiber model and compared against a Bead-Rod model (a semi-flexible model) proposed by Ortman. Both models are capable of predicting the data, with the Bead-Rod model performing slightly better. Orientation occurs at a much faster rate under startup of planar extension, and also attains a much higher degree of flow alignment when compared with startup of steady shear.

Large scale machines (LSMs) are always crucial equipments in manufacturing. Maintaining reliability, precision and safety for LSMs is very important. However, LSMs always work under extreme condition and are prone to degradation or failure. Therefore, maintenance is important for them. Compared with preventive maintenance, predictive maintenance is cost-saving. Besides, predictive maintenance is a more sustainable way by reducing failure and enhancing safety. Condition perception is needed in predictive maintenance. Due to the complex structure and large scale of LSMs, the perception data can be characterized as Big Data. Therefore, the storage and processing of Big Data needs to be integrated into maintenance. Considering that LSMs can be distributed all over the word, cloud service can be a proper way to support maintenance in a global environment. In this paper, a framework of service-oriented predictive maintenance for LSMs based on perception Big Data is synthesized to meet those demands. The methodologies are discussed as well. Finally, an industry case is studied to illustrate the implementing of predictive maintenance.

Requirements for moving beyond the current state of the art in polymer-matrix composites for large commercial and military transport aircraft via the use of liquid molding will be presented. These requirements will be rooted in understandings of regulatory safety requirements and in recent developments in materials and modeling. Key parameters such as the interrelationships between modeling, quality control, and scale-up will be discussed in some detail with a focus on how these need to be matured or adapted for aerospace usage and how they address the persistent need for improved performance at reduced weight. Ongoing work in several technologies will be presented relative to how they fit into the maturation of next-generation composites and tools for developing new composite materials. Scale-up will be illustrated by examples in modeling moving up from material-property-level requirements to system-level performance and moving down to micro and submicron level. These illustrations will be used to show an approach for effectively moving between scales in modeling, testing, fabrication, and design.

Material handling process on assembly lines is important because poor planning and control policies lead to low utilization of workforce and resources, which will cause more inadequate part delivery (part starvation) and reduce the overall system performance. Therefore, the delivery system must be optimized such that minimum number of workforce can be achieved without sacrificing production rate. In real assembly process, for better safety and higher efficiency, dolly trains are widely used to replace traditional forklifts for part delivery, which allows drivers to deliver more than one parts per trip and raises problems: how to choose proper number of parts and the delivery order at the beginning of each trip to achieve optimal dispatching control. Effective algorithms and strategies are addressed and compared in this study to provide practical guidelines for dolly material handling system.

Die structure behavior and its stability are playing more important roles in stamping of advanced high-strength steel (AHSS) sheet metals since the die structure has to maintain steady forming conditions when larger forming load is generated and applied on the die components. Before the workshop try-out, the virtual testing tool is necessary to assure the stamping die design safety. In this paper, a reliable and efficient method to forecast the die structure performance using an updated load mapping algorithm was proposed to verify the stamping die structure design. Furthermore, an improved method for sheet metal forming modeling with non-rigid tooling definition was also presented to enhance the prediction accuracy. In order to validate the proposed method, a step-shaped-bottom cup drawing die was developed and a data collection system was also adopted to measure the strain/stress evolution at specified locations and to reveal the phenomenon of tooling deflection during the AHSS sheet metal drawing process. The comparison between experimental results and prediction demonstrated very good correlation, and the revised method is more accurate and efficient and is expected to be used to verify the industrial AHSS stamping die designs and support the further research on die structure optimization.

Buckling of plates and tubes plays an important role in structural safety and energy absorption. Although buckling of plates and tubes has been studied theoretically and experimentally in the past, the effects of aspect ratio and side constraint on buckling of multi-wall structures and tubes has not been investigated systematically. In this work, finite element simulations have been carried out to investigate the buckling behavior of multi-wall structures and tubes. A series of one- to three-panel walls and square tubes with various aspect ratios were simulated. The critical aspect ratios causing buckling mode transition were obtained and compared with theoretical predictions available in the literature. Effects of wall angle and side constraint on buckling behavior were investigated. The relevance of research findings to honeycomb-like structures was discussed.

This paper describes the milling “super diagram” that incorporates limitations to milling productivity and part quality imposed by stability, surface location error (part errors due to forced vibrations), and tool wear. Combinations of axial depth of cut and spindle speed that offer stable cutting conditions with an acceptable, user-defined surface location error level are identified by a gray-scale color coding scheme. The effect of tool wear is included through the force model coefficients (that relate the cutting force to the chip area) used for process dynamics prediction. Because the force model coefficients vary as a function of the volume of material removed, a unique super diagram is constructed for any user-defined volume of material removed with the selected cutter. For example, preferred operating conditions for a new tool can be compared to those for a worn tool. Additionally, user beliefs about data and model accuracy are applied to identify safety margins relative to the deterministic boundaries in the diagrams. Experimental results are provided for an inserted (carbide) cutter used to machine 1018 steel. The wear behavior is characterized as changes in the force model coefficients as a function of the volume of material removed. The flank wear is also measured using an on-machine microscope (to avoid tool removal from the spindle) and correlated to the force model coefficients. Stability diagrams are developed that correspond to the new and worn tool performance and experimental results are provided to verify changes in the process stability due to tool wear.

Hot forming of ultra high strength steel is an advanced forming technique which can not only represent the best solution to increasing the strength-to-mass ratio of sheet components, but also meet the need of higher passive safety and weight reduction. Based on independently developed mass production line of hot forming, its key forming and quenching technique and relative equipments are proposed and described, including multi-step and one-step method, die manufacturing with cooling system, continuous heating furnace and integrated manufacturing system composed of the advanced interdisciplinary technology of machining, electronic control, material and chemical engineering. Then the automobile body components are produced by the developed equipments of hot forming and moreover their mechanical properties are investigated. The typical tensile curve of the quenched components shows that the yield stress of the hot forming component is over 1000MPa, and the strength limitation is over 1600MPa. The three-point bending testing of the part is implemented. These experimental results indicate the validity of the developed technique and equipments.

The constantly increasing economical and ecological concerns in the automotive and aerospace industries have resulted in high demand for improved fuel economy and greater vehicle performance. Lightweight construction is critical for reducing inertial and rolling resistance losses to increase the product performance while maintaining safety and functional requirements. This will open a wide variety of opportunities to implement materials with high strength-to-weight ratios, such as aluminum, magnesium, stainless steel and titanium alloys. However, when using conventional forming processes, these light materials bring about processing challenges: low formability, high yield strength and low strain hardening coefficients. Electrically-Assisted Forming (EAF) is a method of overcoming these limitations. Specifically, EAF is a novel forming process where electricity, AC or DC, is applied to the metallic workpiece through the dies during deformation. Previous experimental investigations have shown that EAF can lead to reductions in flow stress and power consumption, increase in formability through larger achievable strains, the ability to reduce/eliminate springback, and improved precision. This study investigates the influence of electricity on the different lubrication mechanisms by evaluating lubricant performance in an EAF process and identifying potential lubricant candidates for EAF. The tribological conditions have a significant influence on the frictional forces occurring at the die/workpiece interface, thus on the forming load, part quality, and achievable form. When electricity is applied, besides the changes due to surface expansion at the interface occurring in conventional processes, the lubricant is exposed to high localized temperatures and current fields. To analyze this, electrically-assisted ring compression tests are conducted and the performance characteristics of several lubricants are studied. By combining the experiments and finite element simulation results, friction coefficients can be estimated, and the effect of electric current flow on friction characteristics quantified. One goal of this study is to identify possible lubricant candidates to be used in EAF processes.