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Since the multi-component of powder metallurgy was dispersed, and each component sheared flow and tiered under the action of friction force, it was difficult to disclose the evolution characteristics of each component. Meanwhile, third body mixing with particles of each component covered on the friction surface, which further increased the difficulty of understanding evolution of each component and the corresponding third body in the friction process. To solve this problem, this paper aims to propose a mechanical assembled method which compact several component sheets in order.

Pure copper, aluminum and artificial graphite sheets with thickness 0.5, 1 and 2 mm, respectively, were assembled into a jig by mechanical compact method. The relationship between arrangement patterns of the components and its friction coefficient was studied by using fixed speed friction test machine, the speed range from 200 to 2,000 r/min and the pressure range from 0.25 to 0.64 MPa.

The testing results showed that when the distribution of same components was congregated, friction coefficient dropped from 0.6 to 0.4. While the distribution of different components was dispersed, friction coefficient dropped from 0.6 to 0.25. The friction coefficient decline was caused by performances changes of third body fluidity. The sufficiently mixed third body made third body adhesion weaker and increased third body fluidity. That provoked friction coefficient decreasing obviously at high speed. On the contrary, with the high congregation of same components, strong third body adhesion led to a rougher surface which contributed to a higher friction coefficient.

By means of the mechanical-assembled multi-layer components to reveal the influence mechanism of every component on friction properties, will provide a new test approach for tribology.

This paper aims to obtain high mechanical strength and good self-lubricating property of iron-based powder metallurgy materials. A new type of bilayer material with dense substrate and porous surface was proposed in this paper to obtain high strength and good self-lubricating property.

The materials were prepared by powder metallurgy. Their friction and wear properties were investigated with an end-face tribo-tester. Energy dispersive spectrometer, X-ray diffraction and the 3D laser scanning technologies were used to characterise the tribological properties of materials. The tribological and bearing mechanisms of the monolayer and bilayer materials were compared.

The results show that adding proper TiH₂ can effectively improve the porosity and hardness. With the TiH₂ content increased from 0 to 4 per cent, the average friction coefficients increase slowly, and the wearability decreases first and then increases. When containing 3.5 per cent TiH₂, high strength and good self-lubrication characteristics are obtained. Besides, the tribological properties of monolayer materials are better than those of bilayer materials when the load is between 980 and 1,470 N, while the opposite result is obtained under the load varied from 1,470 to 2,450 N. In the bilayer material, the porous oil surface can lubricate well and the dense substrate can improve the mechanical property. So, its comprehensive tribological and mechanical properties are better than those of monolayer material.

The friction and wear properties of a new type bilayer materials were investigated. And their tribological mechanisms were proposed. This work can provide a theoretical reference for developing high-performance iron-based oil materials under boundary lubrication.

The stress recovery procedures discussed in the present paper refer to a multi‐layered element of assembled Timoshenko beam elements. Directly calculated stresses for a multi‐layered beam model strongly depend on properties of the approximation functions, and are unrealistic. Thus, an enhanced procedure which circumvents the limitations of the interface variables model, and hierarchical model is proposed. Each material layer of the beam element is covered by one quadrilateral 9‐node element, providing a parabolic approximation of displacements. The stresses are evaluated using 2 × 2 Gauss points, projected to corner nodes, and smoothed within material layers. Numerical calculations show very good accordance of stresses yielded by this procedure with 2D results.

The paper aims to present a modeling method for multi‐layer, multi‐material printed circuit boards (PCBs) in both micro‐structure and board levels.

The method incorporates a multilayer finite element model that is established in two parts: the first part is an elasto‐plastic damaging model, which is presented to model metallic plies in the multi‐layer PCBs, while the second is a bi‐phase model for glass‐fiber/epoxy‐resin composite ply with fiber/matrix structure.

Numerous composite parts and complex material properties of multi‐layer PCBs complicate the reliability of the simulation. Therefore, the board level simulation and the micro‐structure modeling cannot be performed at the same time. A multi‐layer FEM code can solve this problem: with the use of bi‐phase and elasto‐plastic plies in this code, the micro‐structure and board‐level modeling for multi‐layer PCBs can be incorporated.

With the implementation of a virtual boundary method, the current multi‐layer model can be combined with the unit‐cell modeling method to perform detailed analysis at the micro‐structure level.

This paper presents a method for multi‐layer PCB modeling at both the micro‐structure and board levels. It provides a way to individually design the fabric types and the properties of glass fibers, epoxy resin, and copper foil in PCBs, to meet specific reliability requirements. With the proposed modeling, the static and shock responses of optimized PCBs can be analyzed with less computation.

The purpose of this paper is to present an efficient algorithm for multi-layer garment fitting simulation based on the geometric method to solve the low time cost problem during penetration detection and processing. This is more practical to design a CAD system to preview the multi-layer garment fitting effect in daily life.

The construction of a multi-layer garment based on existing 3D garments is a suitable method because this method is similar to the daily method of multi-layer dressing. The major problem is the penetration phenomenon between different garments because these 3D garment’s geometric shapes are constructed in different situations. In this paper, an efficient algorithm of multi-layer garment simulation is reported. A face-face intersection detection algorithm is designed to detect the penetration region between multi-layer garments fast and a geometric penetration processing algorithm is presented to solve the penetration phenomenon during multi-layer garment simulation.

This method can quickly detect the penetration between faces, and then deal with the penetration for multi-layer garment construction. Experimental results show that this method can not only remove the penetration but basically maintain the trend of wrinkles efficiently. At the same time, the garments used in the experiment have almost more than 5,800 faces, but the resolving time is under five seconds.

The main originalities of the multi-layer garment virtual fitting algorithm based on the geometric method are highly efficient both in terms of time cost and fitting effect. Based on this method, the technology of multi-layer garment virtual fitting can be used to design a novel CAD system to preview the multi-layer garment fitting effect in real time. This is a pressing requirement of virtual garment applications.

The purpose of this paper is the design and experimental investigation of compact hybrid sound-absorbing materials presenting low-frequency and broadband sound absorption.

The hybrid materials combine microchannels and helical tubes. Microchannels provide broadband sound absorption in the middle frequency range. Helical tubes provide low-frequency absorption. Optimal configurations of microchannels are used and analytical equations are developed to guide the design of the helical tubes. Nine hybrid materials with 30 mm thickness are produced via additive manufacturing. They are combinations of one-, two- and four-layer microchannels and helical tubes with 110, 151 and 250 mm length. The sound absorption coefficient of the hybrid materials is measured using an impedance tube.

The type of microchannels (i.e. one, two or four layers), the number of rotations and the number of tubes are key parameters affecting the acoustic performance. For instance, in the 500 Hz octave band (α₅₀₀), sound absorption of a 30 mm thick hybrid material can reach 0.52 which is 5.7 times higher than the α₅₀₀ of a typical periodic porous material with the same thickness. Moreover, the broadband sound absorption for mid-frequencies is reasonably high with and α₁₀₀₀ > 0.7. The ratio of first absorption peak wavelength to structure thickness λ/T can reach 17, which is characteristic of deep-subwavelength behaviour.

The concept and experimental validation of a compact hybrid material combining a periodic porous structure such as microchannels and long helical tubes are original. The ability to increase low-frequency sound absorption at constant depth is an asset for applications where volume and weight are constraints.

The purpose of this paper is to familiarize the reader with the capabilities of EFAB technology, a unique additive manufacturing process which yields fully assembled, functional mechanisms from metal on the micro to millimeter scale, and applications in medical devices.

The process is based on multi‐layer electrodeposition and planarization of at least two metals: one structural and one sacrificial. After a period of initial commercial development, it was scaled up from a prototyping‐only to a production process, and biocompatible metals were developed for medical applications.

The process yields complex, functional metal micro‐components and mechanisms with tight tolerances from biocompatible metals, in low‐high production volume.

The process described has multiple commercial applications, including minimally invasive medical instruments and implants, probes for semiconductor testing, military fuzing and inertial sensing devices, millimeter wave components, and microfluidic devices.

The process described in this paper is unusual among additive fabrication processes in being able to manufacture in high volume, and in its ability to produce devices with microscale features. It is one of only a few additive manufacturing processes that can produce metal parts or multi‐component mechanisms.

The purpose of this paper is to present an update of and the latest results from work on a project aimed at monitoring electronic products during the whole life cycle with embedded wireless components.

Business processes of the electronic manufacturing supply chain were analysed. A business case and the system opportunities for life cycle monitoring, based on embedded wireless components system were developed. Radio frequency identification (RFID) assembly technology was adapted for the integration of components into a multi‐layer printed circuit board (PCB).

By storing product‐related information into electronic products, tracing of components, monitoring of processes, operations and costs, environmentally optimised recycling can be enhanced.

The research undertaken so far relates to the embedding of RFID tags into PCBs. Wireless components with more processing power will be used in the next project phase.

The paper details how wireless components can be embedded into multi‐layer PCBs and how a business case for a life cycle monitoring system can be established.

This study aims to investigate crack propagation in a moisture-preconditioned soft-termination multi-layer ceramic capacitor (MLCC) during thermal reflow process.

Experimental and extended finite element method (X-FEM) numerical analyses were used to analyse the soft-termination MLCC during thermal reflow. A cross-sectional field emission scanning electron microscope image of an actual MLCC’s crack was used to validate the accuracy of the simulation results generated in the study.

At 270°C, micro-voids between the copper-electrode and copper-epoxy layers absorbed 284.2 mm/mg³ of moisture, which generated 6.29 MPa of vapour pressure and caused a crack to propagate. Moisture that rapidly vaporises during reflow can cause stresses that exceed the adhesive/substrate interface’s adhesion strength of 6 MPa. Higher vapour pressure reduces crack development resistance. Thus, the maximum crack propagation between the copper-electrode and copper-epoxy layers at high reflow temperature was 0.077 mm. The numerical model was well-validated, as the maximum crack propagation discrepancy was 2.6%.

This research holds significant implications for the industry by providing valuable insights into the moisture-induced crack propagation mechanisms in soft-termination MLCCs during the reflow process. The findings can be used to optimise the design, manufacturing and assembly processes, ultimately leading to enhanced product quality, improved performance and increased reliability in various electronic applications. Moreover, while the study focused on a specific type of soft-termination MLCC in the reflow process, the methodologies and principles used in this research can be extended to other types of MLCC packages. The fundamental understanding gained from this study can be extrapolated to similar structures, enabling manufacturers to implement effective strategies for crack reduction across a wider range of MLCC applications.

The moisture-induced crack propagation in the soft-termination MLCC during thermal reflow process has not been reported to date. X-FEM numerical analysis on crack propagation have never been researched on the soft-termination MLCC.

This paper discusses flip chip on FR‐4 and ceramics using non‐conductive adhesive (NCA), anisotropic conductive film (ACF), or anisotropic conductive paste (ACP). Several ACF and ACP materials with different types of adhesive resin and conductive particles and one NCA material were evaluated. Flip chips were assembled on test vehicles for temperature cycling and high‐temperature high‐humidity tests. The reliability performance of the processes was compared. Flip chip processes using NCA, ACF, or ACP could give satisfactory reliability and high assembly yield for some applications, when the bonding parameters were optimised.