International Journal of Advanced Manufacturing Technology最新文献

The joining of aluminum alloy AA5052 and carbon-fiber-reinforced polyether ether ketone (CF/PEEK) by friction lap welding was investigated under different conditions of surface texturing and process temperatures. The joint quality was evaluated by measurement of the tensile shear force and examination of the joint morphology. The aluminum alloy underwent two different types of surface texturing—mechanical engraving and sandblasting. The welding experiments were then conducted under different tool rotational speeds for each. The temperatures across the weld line were measured during the welding process using thermocouples mounted at specific locations. The temperature distribution at the interface was determined by an inverse heat conduction method. It was found that the temperatures at the interface exceeded the melting temperature of PEEK for all testing conditions but was always below PEEK thermal degradation temperature. It was also found that joint performance of mechanically engraved samples increased with the increase of interface temperatures. This was attributed to the increased mechanical interlocking due to the flow of melted PEEK into the engraved sample’s surface features. The joint strength of sandblasted samples did not change considerably with interface temperatures.

This article focuses on enhancing the range of motion (ROM) of the Tetra II joint, a spherical compliant joint consisting of three internally interconnected tetrahedron-shaped elements that achieve motion through elastic deformation. Despite its excellent precision, this specific design is constrained in terms of ROM due to internal contacts among the tetrahedral elements. To overcome this limitation, this study utilizes a computer-aided engineering (CAE) framework to optimize the configuration of the Tetra II joint and enhance its ROM. The resultant optimized joint, referred to as Tetra III, is subsequently compared to Tetra II in terms of both ROM and center shift. Finite element models (FEM) are employed to validate the optimization results and examine how various tetrahedron-shaped geometries impact the joint’s performance. The newly optimized joint exhibits a significantly higher ROM compared to the previous version, while maintaining excellent precision and overall smaller dimensions. Finally, to demonstrate its manufacturability, the Tetra III joint is produced using selective laser sintering (SLS) technology, with Duraform PA serving as the construction material. The successful fabrication serves as a demonstrative example of the improved design of the Tetra III joint.

The objective of this experimental study is to utilize rotary friction welding (FW) for assembling similar polyamide materials. The application of the SVM approach enables the development of a predictive model for estimating mechanical properties in RFW processes. Furthermore, the optimization of RFW parameters through GA proves pivotal in selecting optimal welding conditions, providing a variety of choices. The welding parameters considered in this study included rotation speed at five levels and traverse speed at three levels. The strength of the welded samples was characterized by a tensile test. Additionally, temperature measurements were taken to determine the maximum temperature in the joint area. The results demonstrated the dependence of tensile strength and maximum temperature on the rotation speed. Maximum tensile strength is achieved at an optimal rotation speed. Moreover, analysis of variance (ANOVA) indicates that rotation speed is the parameter most influenced by tensile strength.

High-entropy alloys (HEAs) are special type of alloy suitably developed for use in petroleum exploration, energy storage devices, medical implants, etc. This is because they possess excellent corrosion, thermal, and mechanical properties. Corrosion characteristic of HEAs prepared via spark plasma sintering is a top notch as the technique generates corrosion resistant phases and homogenous microstructure. This study was aimed at reviewing recent publications on corrosion characteristics of HEAs processed by SPS in order to develop ways of improving their anti-corrosion properties. The resource materials were obtained from Scopus-indexed journals and Google Scholar websites of peer-reviewed articles published within the last 5 years. From the study, it was revealed that incorporation of some elements (Al, Cr, Ti) into HEAs can improve their corrosion resistance, while addition of some others can reduce their brittleness and enhance their stability and formability. It was recommended that optimization of SPS parameters was one of the strategies of generating better corrosion characteristics in HEAs.

Failure of resistance spot welds in computer-aided engineering models is based upon criteria that incorporate test data obtained in various loading conditions including different proportions of tensile, shear, and moment loads. The decomposition of the critical load into its respective shear, tensile, and bending moment components is influenced by the rigid body motion during their corresponding mechanical tests. Continuous tracking of the weld orientation and the deformed coupons is required for accurate determination of the load components at the onset of failure. A comprehensive experimental investigation was performed to characterize the critical failure load components in combined loading using various orientations of KS-II tests and a range of coach peel coupon geometries. Mechanical testing was coupled with digital image correlation (DIC) to systematically evaluate empirical force-based failure models for resistance spot welds of two third generation advanced high strength steels with optimal and suboptimal fusion zone diameters. New analysis methodologies using DIC were developed to account for rotation and deformation of the joint in the determination of the shear, normal, and bending moments acting on the spot-welded joints. The coach peel test results for both steels revealed a non-convex experimental fracture locus in bending-tension loading cases. The conventional assumption of a convex failure locus overestimated the critical bending moment strength between 7 and 66%. Results indicated that changes in the operative failure mechanism from pullout/partial-pullout to interfacial can expand the fracture loci within the shear-tensile loading mixities. Improved alternative functional forms for the weld failure models were proposed and contrasted with conventional models that assume convexity.

This research delves into the numerical predictions of fill-level and residence time distribution (RTD) in starve-fed single-screw extrusion systems. Starve-feeding, predominantly used in ceramic extrusion, introduces challenges which this study seeks to address. Based on a physical industrial system, a comprehensive 3D computational fluid dynamics (CFD) model was developed using a porous media representation of the complex multi-hole plate die. Validations performed using real sensor data, accounting for partial wear on auger screw flights, show an ~11% discrepancy without accounting for screw wear and ~6% when considering it. A 2D convection-diffusion model was introduced as a dimensionality reduced order model (ROM) with the intention of bridging the gap between comprehensive CFD simulations and real-time applications. Central to this model’s prediction ability was both the velocity field transfer from the CFD model and calibration of the ROM diffusion coefficient such that a precise agreement of residence time distribution (RTD) curves could be obtained. Some discrepancies between the CFD and the ROM were observed, attributed to the loss of physical information of the system when transitioning from a higher fidelity CFD model to a semi-mechanistic ROM and the inherent complexities of the starved flow in the compression zone of the extruder. This research offers a comprehensive methodology and insights into reduced order modeling of starve-fed extrusion systems, presenting opportunities for real-time optimization and enhanced process understanding.

The demand for 3D-printed high-performance polymers (HPPs) is on the rise across sectors such as the defense, aerospace, and automotive industries. Polyethyleneimine (PEI) exhibits exceptional mechanical performance, thermal stability, and wear resistance. Herein, six generic and device-independent control parameters, that is, the infill percentage, deposition angle, layer height, travel speed, nozzle temperature, and bed temperature, were quantitatively evaluated for their impact on multiple response metrics related to energy consumption and mechanical strength. The balance between energy consumption and mechanical strength was investigated for the first time, contributing to the sustainability of the PEI material in 3D printing. This is critical considering that HPPs require high temperatures to be built using the 3D printing method. PEI filaments were fabricated and utilized in material extrusion 3D printing of 125 specimens for 25 different experimental runs (five replicates per run). The divergent impacts of the control parameters on the response metrics throughout the experimental course have been reported. The real weight of the samples varies from 1.06 to 1.82 g (71%), the real printing time from 214 to 2841 s (~ 1300%), the ultimate tensile strength from 15.17 up to 80.73 MPa (530%), and the consumed energy from 0.094 to 1.44 MJ (1500%). The regression and reduced quadratic equations were validated through confirmation runs (10 additional specimens). These outcomes have excessive engineering and industrial merit in determining the optimum control parameters, ensuring the sustainability of the process, and the desired functionality of the products.

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Abstract

The conventional repairing of CFRP (continuous fiber-reinforced polymer composites) includes complicated steps of patching, splicing, repairing, and post-curing. Intensive labor work needs to be conducted, and poor surface quality and weak interfacial adhesion are usually observed. This work mainly introduces an in situ online repairing method using AM (additive manufacturing) facilitated composite fabrication. With the advances of the robotic-assisted AM process, the surface roughness and accuracy during the repairing process can be evaluated online upon layer-by-layer process. In order to fulfill the efficient and on-site requirements for repairing damage in structural components, this study explores the method including in situ repairing, laser point clouds online collection, and repairing path planning based on multi-axial additive manufacturing of composites. A repair algorithm is proposed incorporating point clouds collection, measurement evaluation, and path planning. Furthermore, relevant mechanical measurements have been conducted, so as to assess the interface degree of recovery. A rapid online evaluation and surface conformal repairing method have been proposed to overcome the technical bottleneck of in situ automatic repairing of damaged composites. It expands the application of multi-axial robot-assisted CFRP AM.

Deriving inspiration from natural hierarchical superhydrophobic surfaces, multi-scale structures were manufactured on AA6082 surfaces via wire electrical discharge machining (WEDM), featuring microscale texture due to spark erosion, superimposed upon a wide-range simple and more complicated geometries of submillimeter profiles. The effect that the higher-order scale morphologies had on wettability was investigated. The dual-scale morphology elevated the hydrophobicity of the surfaces compared to single-scale or unmodified surfaces, reaching superhydrophobicity (151°) in the case of a certain triangular profile. Rectangular and triangular profiles facilitated the higher contact angles, while re-entrant geometries were able to totally prevent cavity wetting. A correlation of static contact angle with roughness parameters of the larger scale such as Ra, Rz, Rp, Rsk, and Rku for certain geometry configurations was identified. Peak hydrophobicity resulted at Ra = 70 μm, Rz = 240 μm, and Rp = 160 μm concerning simple geometries. Negative Rsk and Rku > 1.5 affected negatively contact angle of samples. All investigated tested types were found to reach higher hydrophobicity at moderate drop volumes (5 μl). The fabricated samples were anisotropic in at least two directions, showing decreased hydrophobicity in the front, parallel to the groove direction. When tested in multi-directional dynamic tilting up to 90°, the more complicated geometries were able to retain resistance to spreading. All samples demonstrated superliquiphilicity with lower surface tension liquids, making them strong candidate in applications such as oil/water separation. Finally, all samples tested sustained their hydrophobic character subsequent to a 3-month atmospheric exposure period.

The reasonable allocation of geometric errors of machine tools can improve their machining accuracy reliability (MAR). However, due to the complexity and high nonlinearity of limit state function (LSF) of MAR, the fitting accuracy is usually low when the traditional method is used to approximate LSF. To solve this problem, a doubly-weighted vector projection response surface (DWVPRS) method, which considers not only the approximation results of test sample points (TSPs) to LSF but the distances between TSPs and the most probable failure point (MPFP), is proposed. Using the reliability sensitivity analysis method, the key geometric errors were identified and optimized. Finally, taking a large gantry guideway grinding machine as an example to verifies the effectiveness and correctness of the DWVPRS method proposed in this paper, the results show that compared with the traditional methods, the DWVPRS method has the highest fitting accuracy to approximate LSF at the MPFP, and after the optimization of geometric accuracy, both the minimum and average reliability values of the grinding machine meet the design requirements.