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Due to their excellent properties, carbon fiber-reinforced plastic (CFRP) composites are attractive in many industries, including aerospace, automobile, sports, etc. The structure of anisotropy and heterogeneity and the high abrasive resistance of carbon fibers make CFRPs difficult to cut in surface grinding processes. Many problems, including high cutting force, high tool wear, severe delamination, and high cutting temperature, are associated with conventional surface grinding processes. To reduce or eliminate these problems, surface grinding of CFRP composites using rotary ultrasonic machining (RUM) has been conducted. Machining variables play dominant roles in such a process. However, no investigations on effects of machining variables on output variables were reported. This paper, for the first time, reports effects of machining variables (ultrasonic power, tool rotation speed, feed rate, and depth of cut) on output variables (cutting force, torque, and surface roughness). The results revealed that the cutting force could be decreased by using higher level of ultrasonic power, higher level of tool rotation speed, lower level of feed rate, or lower level of depth of cut. Lower surface roughness could be achieved by a decrease of ultrasonic power, an increase of tool rotation speed, a decrease of feed rate, or a decrease of depth of cut. The machined CFRP surfaces’ morphology and the characteristics of damaged carbon fibers were, for the first time, analyzed and reported in such a process.

The carbon fiber reinforced plastic (CFRP) composites have superior properties of high modulus-to-weight ratio, high strength-to-weight ratio, good durability, high corrosion resistance, and low thermal expansion coefficient. These properties make them attractive in many different applications, such as aerospace, medical, transportation, and sporting goods. However, CFRP’s properties of anisotropy, inhomogeneity, and abrasive properties of carbon fibers in CFRP composites generate many problems, including high cutting forces, high torque, delamination, high tool wear, decomposition of matrix material, etc., in traditional grinding processes. Surface grinding of CFRP composites using rotary ultrasonic machining (RUM) is used to decrease these problems. However, there is no investigation on effects of workpiece machining orientations in such a process. This investigation, for the first time, studies effects of workpiece machining orientations and machining variables (including tool rotation speed, feedrate, and ultrasonic power) on output variables (including both cutting force in feeding direction and cutting force in axial direction, torque, and surface roughness). The results show that lower cutting forces and torque are generated by using 90° workpiece machining orientation and lower surface roughness is produced by using 0° workpiece machining orientation. The results are discussed and analyzed, and they will fill in the research gaps in RUM surface grinding of CFRP composites.

Purpose The purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal weaknesses such as porosity, coarse primary TiB whisker and heterogeneous distribution of TiB reinforcement in the LENS-fabricated TiB reinforced Ti matrix composites (TiB-TMC) parts. Design/methodology/approach An experimental investigation is performed to achieve the results for comparative studies under different fabrication conditions through quantitative data analysis. An approach of microstructural characterization and mechanical testing is conducted to obtain the output attributes. In addition, the theoretical analysis of the physics of ultrasonic vibration in the melting materials is presented to explain the influences of ultrasonic vibration on the microstructural evolution occurred in the part fabrication. Findings Because of the nonlinear effects of acoustic streaming and cavitation induced by ultrasonic vibration, porosity is significantly reduced and a relatively small variation of pore sizes is achieved. Ultrasonic vibration also causes the formation of smaller TiB whiskers that distribute along grain boundaries with a homogeneous dispersion. Additionally, a quasi-continuous network (QCN) microstructure is considerably finer than that produced by LENS process without ultrasonic vibration. The refinements of both reinforcing TiB whiskers and QCN microstructural grains further improve the microhardness of TiB-TMC parts. Originality/value The novel ultrasonic vibration-assisted (UV-A) LENS process of TiB-TMC is conducted in this work for the first time to improve the process performance and part quality.

For carbon fiber-reinforced plastic (CFRP) composite components, especially advanced CFRP components with complex three-dimensional features, surface grinding is often needed to generate final dimensions and functional surfaces. Surface damages are frequently induced during surface grinding, reducing the load-bearing capability and service life of the components. Therefore, it is desirable to perform surface grinding of CFRP in a high-quality and high-efficiency way. Rotary ultrasonic machining (RUM) surface grinding has been investigated to machine CFRP for improved surface quality. Cutting force is one of the most important output variables for evaluating RUM surface grinding. The modeling of cutting force is essential to effectively control the occurrence of surface damages during RUM surface grinding of CFRP. In the RUM surface grinding process, the workpiece material is primarily removed by abrasives on the tool peripheral surface, thus it is essential to investigate the feed-direction cutting force model. However, such models are not available in the literature. In this study, for the first time, a mechanistic feed-direction cutting force model in RUM surface grinding of CFRP is established based on the assumption that the material is removed by brittle fracture. The mechanistic model has one parameter, fracture volume factor of the workpiece material, which needs to be determined by an experiment. There is a good consistency between theoretically predicted trends and experimentally observed results on the relationships between feed-direction cutting force and input variables.

Rotary ultrasonic machining (RUM) has become an effective process for both hole making and surface grinding of carbon fiber reinforced plastic (CFRP) composites. Unlike other brittle materials such as ceramic, glass, silicon, etc., CFRP composites exhibit inhomogeneous and anisotropic properties, thereby resulting in different material removal mechanisms. However, the material removal mechanism in RUM of CFRP is still not clearly recognized in the literature. The lack of such knowledge would significantly limit the optimization and practical applications of RUM technique. In this work, single-grain diamond scratching tests without and with ultrasonic vibration are conducted to study the material removal mechanism in RUM of CFRP. Morphology of scratched groove, cross-sectional profiles, and scratching forces are analyzed. The results indicate that CFRP workpiece is extensively removed by the brittle removal mode, causing matrix damage, severe fiber pull-out, and macro-cracks in the conventional scratching test. Whereas, ultrasonic vibration-assisted scratching of CFRP leads to a larger ductile removal region before the successive brittle fractures and cracks. The fiber-matrix debonding and pullout phenomena are also remarkably reduced with only matrix buckling and fiber breakage occurring within the groove. The obtained results will enrich the understanding of the material removal mechanism in RUM of CFRP and contribute to the improvements of part quality during RUM of CFRP.

Edge surface grinding has been widely applied in achieving functional surfaces and repairing the damage surfaces of carbon fiber–reinforced plastic (CFRP) composites especially with complex three-dimensional features. The conventional surface grinding (CSG) usually generates surface damages, leading to reduced service life and load-carrying capability of the parts. Therefore, there is a critical need to develop a surface grinding process of CFRP composites in a high-quality and high-efficiency way. Rotary ultrasonic machining (RUM) surface grinding has been proven to be such a process. In addition, RUM edge surface grinding can be conducted by up surface grinding or down surface grinding. However, the difference between up surface grinding and down surface grinding with RUM has not been reported. In this paper, the comparison between up surface grinding and down surface grinding with RUM is studied for the first time. The effects of the grinding parameters on machining performance, including cutting force, surface roughness, and surface morphology characteristics, are experimentally studied. The results show that the cutting forces in up grinding are obviously larger than those in down grinding. Lower surface roughness is generated by down grinding when grinding parameters are kept unchanged. The reasons for the differences of cutting forces and surface integrity are discussed. Surface morphologies suggest clearly that brittle fracture is the predominant material removal mode in grinding of CFRP composites. The chip size of the resin, the fracture size of the carbon fiber, and the material removal scale are smaller in down grinding. Furthermore, compared with CSG, the advantages of RUM surface grinding are presented. This investigation will provide useful guidance for surface grinding of CFRP composites.

Ceramic reinforced Ti matrix composites (TMCs) have been widely used under severe friction and heavy loading conditions due to their superior properties. Among different types of ceramic reinforcements, TiB is considered as one of the most suitable ceramic reinforcement materials for TMCs because of its high strength and stiffness, excellent interfacial bonding with Ti matrix, and low induced stress. As a laser additive manufacturing process, laser deposition-additive manufacturing (LD-AM) has been successfully utilized to fabricate Ti-based materials. However, investigations on LD-AM of in situ TiB reinforced TMCs are limited. This investigation, for the first time, reports the tomography analysis of TiB reinforcement within Ti matrix and the formation of novel flower-like microstructure. The influences of reaction energy on part performance have been explored. In addition, the effects of input fabrication variables (including laser power and Z-axis increment) on part performance (including density, microhardness, and compressive properties) have been investigated, providing guidance on selection of input fabrication variables for future research.

The molten pool temperature during laser engineered net shaping (LENS) could directly affect the microstructure and phase compositions of materials in the molten pool, thereby affecting the mechanical properties of the fabricated parts. To achieve a well-built solid structure, the research on fundamentals and methods of molten pool thermal behavior monitoring is of great significance. Using a high-resolution infrared camera, this paper realized real-time temperature tracking of Inconel 718 deposition in the LENS process. The effects of deposition variables, such as laser power and scanning speed, on the molten pool temperature and cooling rate have been investigated. In addition, the effects of the molten pool temperature on the molten pool depth and dendrite arm spacing (DAS) have been analyzed. The results suggest that the molten pool temperature increases with increasing of the laser power while it drops first and then rises with increasing of the scanning speed. The molten pool temperature increases nonlinearly with increasing of the number of layers during the material deposition process.

The superior properties make carbon fiber-reinforced plastic (CFRP) composites attractive in many applications. After CFRPs’ molding processes, additional machining processes are needed to produce final functional shapes with dimensional precision. Edge trimming is the primary process to cut the edge of CFRP composites. To reduce or further solve the problems in traditional machining processes, edge trimming of CFRP composites with rotary ultrasonic machining (RUM) has been proposed and conducted in this investigation. In RUM edge trimming processes, two different tool orientations (RUM edge trimming with tool end face and RUM edge trimming with tool side face) can be performed. The comparisons of machining performance and machined surface quality between these two different RUM edge trimming processes have been conducted. Smaller ultrasonic vibration amplitude in RUM using tool end face or larger ultrasonic vibration amplitude in RUM using tool side face produces smaller surface roughness. Lower feeding-directional cutting force, lower normal cutting force, and lower resultant force are generated in the process using tool side face. RUM using tool end face produces smaller surface roughness, smaller debris width, microcracking, flowed matrix on machined CFRP surfaces, etc.

This paper explores the specific energy consumption (SEC) and environmental impacts for typical additive manufacturing processes. Also, the paper examines the possibility that ensure the product quality while reducing energy consumption with experimental analysis. The results show that (1) the SEC of additive manufacturing processes is related not only to material characteristics but also to the process input parameters; (2) it is possible to increase the energy efficiency without reducing product quality by adjusting the process rate or selecting different materials; and (3) the global warming potential (GWP) result of AM processes indicates that the GWP is brought about principally by the energy production process. The information provided by this project can also be of benefit to life cycle assessment and other environmental impact assessment related to AM processes.