bluuebunny/crossref_metadata_2025 huggingface dataset:
Screw Forming by Semi-Solid Forging of Aluminum Alloy A7075
Authors: Ogawa Kyohei , Nishida Shinichi , Imai Shogo , Uematsu Daichi , Hagiwara Makoto , Kawawa Mizuki , Tsunoda Kentaro
Published: January 2021

This paper reports the screw forming of aluminum alloy A7075 by semi-solid forging. The experimental devices are a servo press machine and a die cushion. The program motion was used for forging. The nominal diameter of screw is M10. The molten aluminum alloy A7075 was stirred and then semi-solid forged into a female screw under 40 tons with 10 seconds holding during forging. The solid phase rate was 0.3. The microstructure of the specimen that is isometric crystal had sphericalization, and refinement. In the results of compression test at room temperature, the maximum compression rate was 29.4% and the maximum nominal stress was 540 MPa. The screw tightening torque was estimated over 57.55 N · m by torque test. This value indicates for produced M10 screw that the strength is over strength category 8.8 of JIS. These results are indicated that the produced screw is suitable for general applications. In the results of optical observation, the male screw of die transferred to the aluminum forgings. And the surface of screw portion had crack free surface. In summary, screw forming by semi-solid forging of aluminum alloy A7075 was possible.
A Hybrid Meta-Heuristic Approach Considering Workload Balancing for Vehicle Assignment and Routing Problem
Authors: Kawashima Takuma , Sakaguchi Tatsuhiko , Uchiyama Naoki
Published: January 2021

In recent years, due to the globalization of the market and the expansion of e-commerce, logistics optimization attracts keen interest from manufacturing companies and service providers. The service area expands wider and the number of customers increases rapidly, thus logistics service providers need to determine the customer assignments and the routes for their trucks considering not only the efficiency of logistics but also the balance of workload for each truck. Therefore, in this study, we propose a customer assignment and vehicle routing algorithm based on the saving method and the simulated annealing. The algorithm first determines the customer assignment and initial route for each truck based on the saving method to balance the workload consisting of the number of customers, the demand of the customers, and distance. Then the initial route is improved by applying the simulated annealing. To evaluate the effectiveness of the proposed method, we conducted computational experiments. In experiments, we solved the waste collection vehicle routing problem in a Japanese city where the wastes generated from over 1000 customers are collected by 10 trucks starting from 1 depot. We evaluated the total cost consisting of the number of waste collecting points, the amount of waste, and the distance for this case study.
Measurement of Residual Strains As a Parameter of Matrix Cracking in CFRP Laminates
Authors: Fikry M. J. Mohammad , Ogihara Shinji , Vinogradov Vladimir
Published: January 2021

Matrix cracking in CFRP laminates results in degradation of mechanical properties of the material and appearance of residual strains. In this study, the residual strains investigated are experimentally and analytically for CFRP [0/756]s laminates. The strain gauges were used in this study to measure the strains. Due to very small residual strains at the unloading condition, the residual strains were also measured at different stress levels for laminates with different crack densities and are compared with theoretical predictions. Time-dependent viscoelastic behavior of the material is also considered to accurately measure the residual strains due to the occurrence of matrix cracks. This was done by using the strain recovery test when the loads were stopped for 1–1.5 hours during unloading and the strain changes during these times were recorded. The experimental results of the residual strains are in reasonably good agreement with the theoretical predictions. The fiber non-linearity properties of the laminates may cause some experimental data to shift above the analytical line.
Ultrasonic Nondestructive Evaluation Methods Applicable to High-Temperature Environments Based on Optical Fiber Remote Sensing
Authors: Okabe Yoji , Yu Fengming , Saito Osamu
Published: January 2021

The development of reliable heat-resistant structural materials requires nondestructive evaluation (NDE) techniques to evaluate the damage progress during material testing at elevated temperatures. Hence, our optical fiber ultrasonic sensing system with a phase-shifted fiber Bragg grating (PSFBG) sensor was improved to a remote AE measurement system at high temperature. The optical fiber was used as an ultrasonic waveguide from an object material in a high-temperature furnace to the PSFBG sensor placed far from the furnace. As a result, AE signals at about 1000°C were successfully detected keeping their precise waveform. Therefore this method will be useful to evaluate the damage progress in heat-resistant materials under high temperature. Furthermore, the remote PSFBG ultrasonic sensing system was incorporated into the receiving part of a laser ultrasonic visualizing inspector (LUVI) for a high-temperature NDE. The LUVI can visualize the propagation behavior of ultrasonic guided waves in complex shape structures. As a result, the improved LUVI with the optical fiber ultrasonic receiver succeeded in clear visualization of the ultrasonic wave propagation in a ceramic plate at 1000°C. Then an artificial damage formed in the ceramic plate was able to be detected by the observation of reflection waves from the damage. Hence, this system has a potential as an effective and intuitive NDE method in high-temperature environments.
Grinding Performance and Delamination Analysis of FeSiB Metallic Glass Laminate
Authors: Fang Zhenglong , Nagato Keisuke , Sugita Naohiko , Nakao Masayuki
Published: January 2021

FeSiB metallic glass laminate is a state-of-the-art structure for improving the magnetic performance of magnetic core. Extreme strength and hardness due to the amorphous matrix challenge its grinding process with severe tool wear and pronounced delamination. An amount of heat generated during grinding process brings a considerable problem in material crystallization, resulting in an increased magnetic deterioration. In this work, grinding data is presented for grind wheel wear, cutting force and surface quality when routing 8 mm thick FeSiB metallic glass laminate using electroplated CBN grinding points. Grinding experiments were carried out with grinding speeds of 0.5 and 1.5 m/s to investigate the formation of delamination. Energy dispersive x-ray spectroscopy (EDS) and electron back scattered diffraction pattern (EBSD) analyses were conducted to inspect the delamination between the metallic foil layers and detailed microstructure of machined surface, respectively. The relation between the cutting force and delamination was discussed associated with the identification of crystallization condition of machined surface. As a result, plastic deformation between the layers is the primary reason for the inter-laminate circuit short. Load-displacement curve from nano indenter indicated the strain hardening level near machined surface increased with cutting speed.
Microstructure and Mechanical Properties of AlSi12CuNi Alloy Fabricated by Selective Laser Melting
Authors: Hirayama Akihiro , Kaizu Koichi , Kimura Masaaki , Kusaka Masahiro
Published: January 2021

In this study, the microstructure and mechanical properties of AlSi12CuNi alloy fabricated by Selective Laser Melting (SLM) were investigated. Wide range of laser irradiation conditions were selected to optimize the process in terms of optimum volume density. As a result, fabricated objects with a relative density of 99% or higher and no crack could be obtained. The as-fabricated alloy exhibited significantly good mechanical properties; an ultimate tensile strength, a breaking elongation, and micro-hardness in comparison with the conventional die casting AlSi12CuNi alloy. The fine microstructures composed of the α-Al phase and nano-sized eutectic Al-Si network could be observed. The dimensions of the microstructures were smaller than that of the conventional die casting AlSi12CuNi alloy. The superior mechanical properties were attributed to the microstructure associated with the rapid solidification of the SLM process. The influence of building direction of mechanical properties on fabricated objects was evaluated. The ultimate tensile strength and breaking elongation were significantly affected by the building direction, which was higher in the case of a parallel direction to the roller moving direction. AlSi12CuNi alloy with good characteristics can be successfully fabricated by the SLM process.
Measurement and Evaluation of the Static Friction Coefficient Between Fixed Coupling Surfaces Under Face Contact and High Contact Pressure
Authors: Inagaki Fumihiko , Morita Noboru , Hidai Hirofumi , Matsusaka Souta , Ohmori Tatsuo , Chiba Akira , Matsumoto Yuichiro , Shimizu Shinji
Published: January 2021

At the joints of the mechanical systems, it is well known that the parameters such as contact stiffness, static friction coefficient, kinetic friction coefficient and attenuation coefficient affect static, kinetic, thermal and motion characteristic of them strongly. In these parameters, the static friction coefficient reigns the character of maximum fixing resistance. However, there’s difficulties for measure the precise static friction coefficient on the coupling surfaces due to tiny contact surface, unstable loading method and moment force acts on the contact surface of the former device. Therefore, we developed novel measurement device and evaluated influence of the surface parameters given to static friction coefficient.

Through the validity evaluation, it was confirmed that the new measurement device enables face contact and uniform surface pressure. In addition, there’s no moment force by optimizing the loading position of the tangential force. Furthermore, validity of the static friction coefficient was checked and verified that frequency of the sampling rate is fine enough.

Finally, we proceeded to applied test with this new measurement device for evaluate the influence of the surface roughness and grinding direction given to static friction coefficient. A pair of die steels and cemented carbides was selected for specimen and static friction coefficient was measured under 60 MPa of contact pressure. Regarding influence of surface roughness, the result showed tendency that rougher surface generates lower value of the static friction coefficient. Now for grinding direction, combination of the specimen ground in orthogonal direction against tangential force showed maximum value and the specimen ground in parallel direction against tangential force showed minimum.
Study on Method to Avoid Chatter Vibration Based on Machine Tool Rigidity
Authors: Hayashi Akio , Ishibashi Hiroto , Morimoto Yoshitaka , Kaneko Yoshiyuki , Suzuki Naohiko
Published: January 2021

Chatter vibration decreases machining accuracy and thus presents a problem in manufacturing. In order to eliminate chatter vibration based on the estimation of stable cutting conditions from a stability limit diagram and to determine the cutting conditions accordingly has been proposed. However, changing the cutting conditions may lead to a decrease in productivity. The stability limit is estimated from the relationship between machine rigidity and the cutting conditions.

In the present study, we proposed a system to avoid chatter vibration by changing the rigidity of the machine tool. We developed the desktop machine tool that can change its rigidity by varying the preload of a brace bar attached to the frame. In order to clarify the relationship between the chatter vibration and the rigidity of the desktop machine tool, the stability limit of the desktop machine tool was determined by conducting machining tests and comparing the results with a simulated stable limit diagram. We then investigated the frequency response function within the simulation. The results showed that the transition of the stability limit can be accomplished by changing the rigidity of the desktop machine tool, and indicate that chatter vibration can be avoided by simulation.
Debonding Detection at Core/Skin Interfaces in a Honeycomb Sandwich Structure Using a Laser Ultrasonic Visualization Method
Authors: Sen Enhi , Saito Osamu , Higuchi Nobuhiro , Okabe Yoji
Published: January 2021

Honeycomb sandwich structures are widely used in aircraft owing to the superior characteristics, such as the light weight, the high specific bending stiffness and the high specific in-plane compressive strength. However the honeycomb sandwich structures are prone to have debonding damages at the interfaces between the skin and the honeycomb core, which degrades the mechanical properties largely. For inspection of damages in plate-like structures, the propagation of ultrasonic guided waves along the plate is effective. In this research, we attempted to detect the debonding at the skin/core interfaces in a honeycomb sandwich panel by using a laser ultrasonic visualization method. Debonding damages were artificially introduced in a sandwich panel consisting of two CFRP skin plates and an aluminum honeycomb core. Then, ultrasonic guided waves were excited in the panel through scanning of a laser irradiation on a surface of the plate and were received by a piezoelectric sensor installed on the same surface by using a laser ultrasonic visualizing inspector. As a result, we obtained visualization animations of the ultrasonic propagation behavior. From the change in the maximum amplitude distribution of the guided wave, we were able to identify the debonding damages at the skin/core interfaces in both the laser-irradiation side and the opposite side. Furthermore, a finite element analysis of the ultrasonic propagation in the honeycomb sandwich panel was conducted to confirm the phenomena observed in the experiments. From the calculation results, the mechanism of the observed phenomena was able to be clarified.
Control of Laser-Induced Periodic Surface Structures Assisted by Mechanical Processing
Authors: Kodama Shuhei , Takase Ryohei , Shimada Keita , Mizutani Masayoshi , Kuriyagawa Tsunemoto
Published: January 2021

Fine structures provide materials with various functionalities such as friction reduction and water repellency. A short-pulsed laser is a suitable method to effectively fabricate fine structures through self-organization, called as LIPSS (laser induced periodic structures). However, this method has difficulty in control of LIPSS since the principles and the phenomena have not been clarified completely. It has been reported that LIPSS follow debris on a material surface, hence, the short-pulsed laser assisted by mechanical processing was proposed, and the straightness and the aspect ratio of LIPSS were improved by laser irradiation on the surface with the straight microgooves. The short-pulsed laser assisted by mechanical processing was developed to control LIPSS and fabricate zigzag LIPSS, and the effects of the surface geometry before laser irradiation on LIPSS were investigated. Firstly, laser irradiation was conducted on the microgrooved surfaces with changing the angle of laser polarization to investigate the effects of the angle between groove direction and laser polarization on LIPSS. When the angle were from 45° to 90°, LIPSS followed the microgrooves regardless of the laser polarization. Based on the results, the laser was irradiated on the surfaces with zigzag microgrooves created by ultraprecision cutting, and zigzag LIPSS were fabricated as following zigzag microgrooves under the proper conditions. This study demonstrated the importance of the initial surface shape and the effectiveness of the short-pulsed laser assisted by mechanical machining to control LIPSS freely since the surface plasma waves are propagated from unevenness on the material surface.
Effect of Interfacial Nanostructure on Mode Mixity in Directly Bonded Carbon Fiber Reinforced Thermoplastic Laminates and Aluminum Alloy With Thermal Stresses
Authors: Ota Hiroki , Jespersen Kristine Munk , Saito Kei , Wada Keita , Okamoto Kazuki , Hosoi Atsushi , Kawada Hiroyuki
Published: January 2021

In recent years, for the aim of weight reduction of transportation equipment, carbon fiber reinforced thermoplastics (CFRTPs), which have high recyclability and formability, are becoming suitable for mass production. Additionally, with the development of multi-material structures, excellent technologies for joining metal and CFRTPs are required. In present industry, joining between dissimilar materials include adhesive bonding and mechanical joining methods, however, these methods still have some problems, and therefore an alternative bonding method without adhesive and mechanical joining is required for joining CFRTPs and metals. Thus, this study focused on direct bonding between CFRTP and an aluminum alloy, by producing a nanostructure on the surface of the aluminum alloy. The nanostructure penetrates the CFRTP matrix causing an anchoring effect, which results in significant bonding strength improvement. The influence of the nanostructure on the fracture toughness for the directly bonded CFRTP and aluminum was evaluated by static double cantilever beam (DCB) testing. Due to the difference of the thermal expansion coefficients between the CFRTP laminates and the aluminum alloy, significant residual stresses are generated. The effect of the thermal residual stresses on the fracture toughness along with the resulting mode mixity (mode I and II) was calculated. It is found that the thermal stresses introduce a significant mode mixity of the fracture toughness.
Development of High-Performance Polycrystalline CVD Diamond Coated Cutting Tool Edge With Femtosecond Laser
Authors: Liu Xiaoxu , Natsume Kohei , Maegawa Satoru , Itoigawa Fumihiro
Published: January 2021

To realize the high performance of CVD diamond coated tools, a tool edge shaping process named pulse laser grinding (PLG) was developed with short pulse laser in our group previously. In this study, femtosecond laser was innovatively to be used to conduct the PLG process, since femtosecond laser is famous for its less thermal impact and some newly reported surface modification effect. The results show that PLG processing under high laser fluence of femtosecond laser could achieve roundness around 1 μm, which is similar to that of conventional PLG process with nanosecond laser, although the roughness of processed surface has been worse due to the redeposited debris. Furthermore, an interesting phenomenon has been confirmed again that under low laser fluence irradiation of femtosecond laser, the CVD diamond surface shows improved crystallinity of diamond structure. Based on this, a two-step tool edge processing method was proposed, which could realize the edge shaping and surface modification together with one laser processor. And the results show that the processed tool edge with much less edge roundness and surface roughness, and the tip part with better diamond crystallinity, indicating that sharper and hardness tool edge could be possibly to be realized with femtosecond laser.
Chatter Stability Prediction of Cutting Process With Process Damping Utilizing Finite Element Analysis
Authors: Suzuki Norikazu , Nakanomiya Tomoki , Shamoto Eiji
Published: January 2021

This paper presents a new approach to predict chatter stability in cutting considering process damping. Traditional chatter stability analysis methods enable to predict stable or unstable conditions. Under unstable conditions, the chatter vibration can increase theoretically infinitely. However, chatter vibration is damped at a certain amplitude in real process due to process damping, i.e., the cutting process is stabilized by means of tool flank face contact to the machined surface. In order to consider the influence of the process damping, a simple process damping force model is introduced. The process damping force is assumed to be proportional to the structural displacement. The process damping coefficient is a function of the vibration amplitude and the wavelength. In order to identify the coefficients, a series of finite element analysis is conducted in the present study. Identified coefficients are introduced into the conventional zero-order-solution in frequency domain. The proposed model calculates chatter stability limit assuming process damping with finite amplitude. Hence, this analysis enables to estimate the amplitude-dependent quasi-stable conditions. Analytical results for thee face turning operation demonstrated influence of process damping effect on resultant vibration amplitude quantitatively.
Effect of Cutting Temperature on Phase Transformation in Cutting of NiTi Alloy
Authors: Yang Hao , Sakai Katsuhiko , Shizuka Hiroo , Hayakawa Kunio , Nagare Tetsuo
Published: January 2021

In this study, the effect of cutting temperature on phase transformation in cutting of room temperature austenitic NiTi alloy was investigated by X-ray diffraction (XRD) and temperature measurements. Results from XRD reveals that after cutting process, the phase state of work material near the machined surface transformed from austenite to martensite at relatively low cutting speed conditions while the phase state of work material did not undergo any form of transformation at the highest cutting speed condition. Temperature measurement results measured with temperature indicating paint showed that the maximum temperature of work material near the machined surface in cutting process exceeded the Md temperature at the highest cutting speed condition. However, there was no phase transformation observed in cutting chips after cutting at all cutting speed conditions as the temperature of cutting chips was much higher than the Md temperature under all cutting speed conditions.
Control of Material Flow During Friction Stir Welding Between Aluminum and Steel by Welding Tool Shape
Authors: Yasui Toshiaki , Ogura Yuki , Huilin Xu , Najwa F. Farrah , Sugimoto Daichi , Ito Atsushi , Fukumoto Masahiro
Published: January 2021

For the Friction stir welding (FSW) between aluminum and steel is important to fabricate vehicles with light weight and high strength for safety at low cost. For the fabrication of sound weld, it is necessary to control the material flow during FSW. In this study, the material flow during FSW was elucidated by numerical simulation by computational fluid dynamics (CFD) analysis and simulation experiment by transparent Poly-vinyle chloride (PVC) as simulant of aluminum and tracer material. Based on this material flow analysis, several shapes of welding tool were examined for control of material flow during FSW. Scroll shoulder is effective for enhancement of stirring zone by increasing material velocity around the probe. Flute and fine screw probe promote the material flow in depth and horizontal direction. The welding tool with scroll shoulder and flute and fine screw probe achieved sound weld with highest tensile strength of 120.4 MPa.
Improvement of the Form Accuracy Ground by a Slender Wheel in Internal Grinding
Authors: Onishi Takashi , Nakabayashi Yusuke , Sakakura Moriaki , Ichiba Go , Ohashi Kazuhito
Published: January 2021

In the case of internal grinding of a deep hole, the inner surface of the hole was ground by a slender grinding wheel that has a high aspect ratio. A slender grinding wheel is bent by the normal grinding force during the grinding process. Therefore, the form accuracy of the ground workpiece is decreased especially when the aspect ratio of a wheel is high. In our previous study, it was confirmed that the biggest factor that generated the form error of the workpiece was the elastic deformation owning to the normal grinding force. To reduce the form error of the ground workpiece, it is effective to expand the spark-out duration. However, the expansion of the spark-out duration leads to the low productivity. In this study, the form of the grinding wheel was modified by a diamond dresser to improve the form accuracy of the workpiece without expanding the spark-out duration. The modified form of a wheel was determined to compensate the form error of the workpiece generated by the elastic deformation of the grinding wheel. Thorough several grinding experiment, it was confirmed that the form accuracy of the ground workpiece was successfully improved by modifying the form of a slender grinding wheel without expanding the spark-out duration.
Thin Film Stress Sensor on the Tool Rake Face for Orthogonal Cutting
Authors: Obikawa Toshiyuki , Yagi Kenji , Hayashi Mamoru
Published: January 2021

The evaluation of stress and temperature on the tool faces during machining is very important for understanding the fundamental mechanism of machining processes, developing cutting tools, optimizing cutting conditions. Although cutting temperature has been often measured using the tool-chip thermocouple method, a two-color pyrometer, etc., measurement of stress on the tool face has been hardly reported. For this reason, a cutting tool with a thin film stress sensor in the surface layer of the rake face was developed for orthogonal cutting. The film sensor was made of manganin, a copper-manganese-nickel alloy having piezoresistance effect. The manganin was coated on the rake face of polished silicon nitride matrix by magnetron sputtering in a specific pattern having a line 30 micrometer wide and 0.2 micrometer thick along the cutting edge. Then, the rake face was further coated with silicon nitride for protecting the thin stress sensor. After the calibration of the sensor, the tool was applied to orthogonal cutting experiment, in which MC Nylon and polyvinyl chloride were machined at a very low cutting speed. For four levels of uncut chip thickness from 0.05 to 0.20 mm the stress was measured for MC Nylon. The measured stress seems consistent with stress distributions measured by photoelasticity method reported so far.
Robustness of Detection Method for Clamp Force Against Configuration Error in Bolt/Nut Assemblies
Authors: Hashimura Shinji , Kubota Kai , Ohmi Nozomu , Komatsu Kyoichi
Published: January 2021

Reliability of bolt/nut assemblies directly influences the quality of machines and structures. It is most important to control and maintain the clamp force of bolt/nut assemblies to secure reliability. However it is not easy to control the clamp force during tightening. And it is also difficult to detect the clamp force after tightening. In our previous study, we proposed a method to easily detect the clamp force of bolt/nut assemblies that have already been tightened. In the method, the bolt thread portion protruding from the nut is pulled while supporting the nut’s upper surface. The relationship between the tensile force and the displacement at the pulling point differs before and after the tensile force reaches the clamp force. The method can detect the tensile force at the point where the relationship changes as the clamp force.

In this study, robustness of the detection method for the squareness error of the bearing surface of clamped parts has been investigated by FE analysis and experiments. The results of the FE analysis showed that the squareness error of the bolt bearing surface does not have an influence on the detection accuracy. The results indicate that the detection method has robustness for the squareness error of bolt bearing surfaces. Contrary to that, the experimental results show that the squareness error does have a clear influence on the detection accuracy. The averages of detection error in the experiments increased about 10% with an increase in squareness error. It is considered that the error was caused because the mating thread surfaces did not separate when the tensile force reached the clamp force.
A Reconfigurable Jig Assistant Assembly System Based on Wearable Devices
Authors: Qin Zhaojun , Lu Yuqian , Zhang Hongbo , Liu Xinyu , Zheng Lianyu
Published: January 2021

In the aviation industry, the novel reconfigurable jig has a good application prospect. However, compared with traditional fixed jigs, the flexible structure of reconfigurable jig increases the assembly difficulty, as well as the disadvantage of cooperation between devices. To cope with these problems, we propose a reconfigurable jig assistant assembly (RJAA) system based on wearable devices in this paper, which can enhance the collaboration between humans and machines, and improve the automation level of assembly operations. Firstly, the architecture of the RJAA system is presented, which is composed of three units, i.e. server application unit, wearable application unit, and assembly execution/auxiliary unit. Secondly, in order to achieve the collaboration within the RJAA system, a unified message cooperation communication protocol is designed. Finally, we tested the developed system on the assembly of a 6-UPS parallel mechanism to validate the effectiveness and feasibility of the proposed system.
Effect of Hatch Angle Rotation on the Thermal and Mechanical Properties of Micro Selective Laser Melted NiTi Shape Memory Alloy
Authors: Fu Jin , Hu Zhiheng , Song Xu , Fu Mingwang
Published: January 2021

NiTi shape memory alloy (SMA) has been widely used for bio-medical and aerospace applications due to its unique properties, i.e. shape memory effect and pseudoelasticity. However, the high ductility and work-hardening effect of NiTi lead to poor machinability. Additive manufacturing (AM), with excellent capability of fabricating complicated structures, has been used to fabricate NiTi components. To meet the increasing demand of product miniaturization, micro selective laser melting (μSLM) system equipped with finer laser beam has been developed to improve manufacturing resolution. This work studies the fabrication of NiTi SMA parts by μSLM for the first time. The effect of hatch angle rotation on the thermal and mechanical behaviors of μSLMed NiTi is analyzed. Columnar grains accompanied with equiaxed grains are observed in μSLMed NiTi. Laser rotation angles of 45/60/90° lead to weak crystallographic texture. Ti-rich secondary phases including Ti2Ni/Ti4Ni2Ox and TiC1-xNx are detected in the raw NiTi powder and the as-printed NiTi parts, respectively. The as-printed parts under different hatch angles show similar phase constitution. The thermal-induced transformation behavior was depressed with absence of transformation peak. The variation of hatch angle cannot activate the transformation peak. Varying hatch angle from 45° to 90°, the compressive strength and ductility reduce, and the hardness increases. The depressed thermal-/stress-induced phase transformation of the μSLM NiTi can be attributed to the Ti-rich secondary phases, which cause variation of matrix Ni/Ti ratio and inhomogeneous microstructure.
Thermal Stress Simulation Model of Dissimilar Linear Friction Welding (LFW) Technology for Manufacturing of Bi-Metallic Biomedical Implants
Authors: Glaspell Aspen , Seydlorsky Christina , Son Junbeom , Ryu Jae Joong , Choo Kyosung
Published: January 2021

Linear Friction Welding (LFW) is a uniquely important manufacturing process because it allows welding of dissimilar materials without filler material. In this study, bi-metallic Ti6Al4V-CoCrMo joints were manufactured using LFW process and analyzed the weldability and bonding strength. Ti6Al4V and CoCrMo cylinders were manufactured to a standard size of tensile specimens and cut into two identical pieces. The surfaces to be welded were polished and cleaned before performing welding. The experimental thermal data was recorded with an IR camera.

In the thermal stress simulation model, the temperature-dependent thermal properties of Ti-6al-4V were used. The thermal properties of CoCrMo were assumed constant due the fact that CoCrMo does not change phase until it reaches its melting temperature. The heat losses due to radiation was different for each workpiece because both materials had a different emissivity and the heat loss by convection is a function of the surface temperature by natural convection. The left boundary of the Ti-6Al-4V and the right boundary of the Co-Cr-Mo workpiece were constrained at a constant temperature of 45°C. The maximum deformation of the simulation model is well matched with the measured data within 5% error.
Experimental Investigation of the Machinability of Single Crystal Silicon in Laser-Assisted Diamond Cutting
Authors: Ke Jinyang , Chen Xiao , Zhang Jianguo , Liu Changlin , Xu Guoqing , Chu Jianning , Xiao Junfeng , Xu Jianfeng
Published: January 2021

Laser-assisted diamond cutting is a promising process for machining hard and brittle materials. A deep knowledge of material removal mechanism and attainable surface integrity are crucial to the development of this new technique. This paper focuses on the application of laser-assisted diamond cutting to single crystal silicon to investigate key characteristics of this process. The influence of laser power on the ductile machinability of single crystal silicon, in terms of the critical depth of cut for ductile-brittle transition in laser-assisted diamond cutting, is investigated quantitatively using a plunge-cut method. The experimental results reveal that this process can enhance the silicon’s ductility and machinability. The critical depth of cut has been increased by up to 330% with laser assistance, and its degree generally increases with the increase of laser power. The cross-sectional transmission electron microscope observation results indicate that laser-assisted diamond cutting is able to realize the subsurface damage free processing of single crystal silicon. In order to verify the ability of the laser-assisted diamond cutting to improve the surface quality, the face turning tests are also carried out. A significant improvement of surface quality has been obtained by laser-assisted diamond cutting: Sz (maximum height) has been reduced by 85% and Sa (arithmetical mean height) has been reduced by 45%.
Research on Intelligent Optimization Algorithm for Multi-Objective Disassembly Line Balancing Problem
Authors: Xu Yunli , Yao Bitao , Pham Duc Truong
Published: January 2021

For resource reutilization and environmental protection, remanufacturing gets more and more attention in many countries. Disassembly is a critical part of traditional manufacturing industry, but the traditional disassembly operation is mainly done by workers, which is low-efficiency. Now the use of robots can improve production efficiency a lot, which involves the problem of disassembly line balancing. Due to the constraints such as product complexity and precedence relationship between tasks, when the number of tasks increases, the combination scheme between tasks increases geometrically, and conventional algorithms are difficult to solve the problems, the Disassembly Line Balancing Problem (DLBP) is generally necessary to optimize multiple objectives. In this research, the author selects a variety of intelligent optimization algorithms to resolve the complex disassembly line balancing problem in different dimensional objective space. Four representative algorithms are selected from three angles to be compared through three performance indicators. It is concluded that these algorithms have different search capabilities for different specifications and objective space. Researchers should carefully select the algorithm according to the specific disassembly problem. The appropriate algorithm should be selected according to the scale of the disassembly line problem and the number of optimization objectives in actual production practice.
Study on the Thermal Expansion Effects of the 3D Printed Space Instrument
Authors: Fursova Anastasiia , Konev Stepan , Velasquez-García Luis , Sun Zhumei , Nikolaev Evgeny
Published: January 2021

Space is one of the most mysterious and unexplored places for humanity. It has a dangerous environment that critically affects everything that is launched there. In this case, an enormous challenge for engineers now is to find cheap but effective manufacturing methods that can provide an instrument that is stable during launch, landing, and work time of the mission. Additive technologies are a credible method for this task. It can provide materials that are stable in the big range of temperature, vacuum, and stresses.

Unfortunately, some of the instruments need high precision of the surfaces that could be damaged during the mission. The mass spectrometer is one of such devices. One of its main parts is the ion trap that extremely sensitive to a displacement of the surface. Our perspective mission is on Moon Polar Caps, where extreme temperatures are. Thermal compression could crucially change surface profile and decrease the quality of the mass spectrometry measurements.

The goal of the research is to conduct a thermomechanical analysis of the 3D printed metal Kingdon ion trap, for the conditions of the Moon surface. At this point, we have created the prototype by inkjet printing techno logy, performed thermal expansion analysis and tests.

Results show that the thermal expansion could significantly affect the performance of the instrument. We are proposing to introduce corrections to the shape of the surface.
A Novel Real-Time Thermal Analysis and Layer Time Control Framework for Large Scale Additive Manufacturing
Authors: Fathizadan Sepehr , Ju Feng , Rowe Kyle , Fiechter Alex , Hofmann Nils
Published: January 2021

Production efficiency and product quality need to be addressed simultaneously to ensure the reliability of large scale additive manufacturing. Specifically, print surface temperature plays a critical role in determining the quality characteristics of the product. Moreover, heat transfer via conduction as a result of spatial correlation between locations on the surface of large and complex geometries necessitates the employment of more robust methodologies to extract and monitor the data. In this paper, we propose a framework for real-time data extraction from thermal images as well as a novel method for controlling layer time during the printing process. A FLIR™ thermal camera captures and stores the stream of images from the print surface temperature while the Thermwood Large Scale Additive Manufacturing (LSAM™) machine is printing components. A set of digital image processing tasks were performed to extract the thermal data. Separate regression models based on real-time thermal imaging data are built on each location on the surface to predict the associated temperatures. Subsequently, a control method is proposed to find the best time for printing the next layer given the predictions. Finally, several scenarios based on the cooling dynamics of surface structure were defined and analyzed, and the results were compared to the current fixed layer time policy. It was concluded that the proposed method can significantly increase the efficiency by reducing the overall printing time while preserving the quality.
Finite Element Method (FEM) Based Simulation of Continuous Laser Ablation: Surface Temperature and Depth Profile Evolution
Authors: Ravi-Kumar Sandeep , Jiang Liangkui , Qin Hantang
Published: January 2021

Laser ablation has been widely used for material removal on different types of substrates. Accurate feature profile fabrication with minimum damage to the surrounding material requires precise control of the laser and material parameters. One approach to achieve this is by establishing a simulation model to help process control and optimization. However, laser ablation is a complex process that is difficult to model. In this paper, numerical simulation models have been established to identify the temperature at the ablation surface and the ablation depth profile evolution over time. The ablation has been modeled using the heat transfer in solids module in COMSOL Multiphysics with the manual material definition of high-density polyethylene (HDPE). The laser beam is modeled as a continuous heat source by utilizing a ramp function. Information for establishing a pulsed laser system has been provided. Results are provided for the surface temperature and depth profile evolution for various time steps. Results of the simulation of laser ablation of HDPE sample using a 50W laser using both the models were presented. The next step of our work is to validate the simulation results by comparing it against experimental data. This will render these models to have the potential to be able to predict the ablation crater profile with higher accuracy. This model will pave the way for a better understanding of the ablation threshold conditions and identifying the ablation initiation in any material, given the material properties are known.
Meta-Data for In-Situ Monitoring of Laser Powder Bed Fusion Processes
Authors: Feng Shaw C. , Lu Yan , Jones Albert T.
Published: January 2021

Increasingly, a wide range of in-situ sensors are being instrumented on additive manufacturing (AM) machines. These sensors collect a variety of data that is used to monitor process performance and part quality. The amount, type, and speed of the collected data are unprecedented. Consequently, several data-related, standards issues are impeding the use of both data analytics and tool integration. Those issues include registration, curation, organization, storage, and management. This paper focuses on registration. It proposes the use of meta-data as a foundation for new interface and exchange standards. Standards that will facilitate the use of several types of in-situ sensors that monitor laser powder bed fusion (L-PBF) processes. The paper also includes an example data model that captures the properties and relationships among those meta-data. The data elements in that model provide industrial users with the capabilities and formats to capture, exchange, and share L-PBF process data.
Method for Obtaining Light Curing Printing Condition Based on New Theoretical Description
Authors: Li Yang , Yin Jun
Published: January 2021

Digital light processing (DLP) is widely used in tissue engineering in recent years. High resolution and high speed are the advantages of this printing method. The method of determining DLP process printing conditions by forming experiments is restricted by the formability of the material and it is difficult to apply to soft materials and materials that are not easily formed. In this study, through theoretical analysis that the concept of absorbances and gel point is introduced into the relationship between exposure time and forming thickness. This allows the forming conditions to be obtained by measurement of only physical quantities related to the nature of the material itself rather than through forming experiments. Which facilitates high-precision DLP printing of biomaterials.
Bio-Inspired Self-Folding of Shape Memory Polymer Sheets by Laser Rastering
Authors: Line Joshua , Abdulhafez Moataz , Bedewy Mostafa
Published: January 2021

Origami-based fabrication strategies open the door for developing new manufacturing processes capable of producing complex three-dimensional (3D) geometries from two-dimensional (2D) sheets. Nevertheless, for these methods to translate into scalable manufacturing processes, rapid techniques for creating controlled folds are needed. In this work, we propose a new approach for controlled self-folding of shape memory polymer sheets based on direct laser rastering. We demonstrate that rapidly moving a CO2 laser over pre-strained polystyrene sheets results in creating controlled folds along the laser path. Laser interaction with the polymer induces localized heating above the glass transition temperature with a temperature gradient across the thickness of the thin sheets. This gradient of temperature results in a gradient of shrinkage owing to the viscoelastic relaxation of the polymer, favoring folding towards the hotter side. We study the influence of laser power, rastering speed and number of passes on the fold angle. Moreover, we investigate process parameters that produce the highest quality folds with minimal undesired deformations. Our results show that we clean folds up to and exceeding 90°, which highlights the potential of our approach for creating lightweight 3D geometries with smooth surface finishes that are challenging to create using 3D printing methods. Hence, laser-induced self-folding of polymers is an inherently mass-customizable approach to manufacturing, especially when combined with cutting for integration of origami and kirigami.
Effect of Oil Flow Rate on Production Through-Tool Dual Channel MQL Drilling
Authors: Raval Jay K. , Stephenson David A. , Tai Bruce L.
Published: January 2021

Minimum quantity lubrication (MQL) drilling has been known for decades, but limited knowledge is available on two-channel through-tool MQL drilling due to the lack of accessibility to production systems. A common problem in MQL drilling is the absence of a rational approach to select the oil flow rate. The limited entry and exit area, and fixed energy available to the flow make the behavior complicated. This study leverages the capabilities in Ford’s manufacturing lab to abridge the research gap. Four different oil flow rates (0 ml/h, 15 ml/h, 30 ml/h and 60 ml/h) and two different drills (twist drill and straight drill) were used to find out the influence of oil flow rate on the cutting performance. Tool life, tool wear, cutting force and torque were monitored as the cutting performance indicators. It was concluded that, the common belief of higher oil flow rate providing better tool life, does not hold true for through-tool MQL drilling. The tool life for 30 ml/hr. oil flow rate appeared to be the highest compared to all the other cases for both the drills. Increasing the oil flow rate above 30 ml/hr. decreased the tool life. However, it is to be noted that the optimal oil flow rate values may be specific to the case.
Uncertainty Quantification in Metallic Additive Manufacturing Through Data-Driven Modelling Based on Multi-Scale Multi-Physics Models and Limited Experiment Data
Authors: Wang Zhuo , Jiang Chen , Horstemeyer Mark F. , Hu Zhen , Chen Lei
Published: January 2021

One of significant challenges in the metallic additive manufacturing (AM) is the presence of many sources of uncertainty that leads to variability in microstructure and properties of AM parts. Consequently, it is extremely challenging to repeat the manufacturing of a high-quality product in mass production. A trial-and-error approach usually needs to be employed to attain a product with high quality. To achieve a comprehensive uncertainty quantification (UQ) study of AM processes, we present a physics-informed data-driven modeling framework, in which multi-level data-driven surrogate models are constructed based on extensive computational data obtained by multi-scale multi-physical AM models. It starts with computationally inexpensive metamodels, followed by experimental calibration of as-built metamodels and then efficient UQ analysis of AM process. For illustration purpose, this study specifically uses the thermal level of AM process as an example, by choosing the temperature field and melt pool as quantity of interest. We have clearly showed the surrogate modeling in the presence of high-dimensional response (e.g. temperature field) during AM process, and illustrated the parameter calibration and model correction of an as-built surrogate model for reliable uncertainty quantification. The experimental calibration especially takes advantage of the high-quality AM benchmark data from National Institute of Standards and Technology (NIST). This study demonstrates the potential of the proposed data-driven UQ framework for efficiently investigating uncertainty propagation from process parameters to material microstructures, and then to macro-level mechanical properties through a combination of advanced AM multi-physics simulations, data-driven surrogate modeling and experimental calibration.