Experimental Study on a Microwave Composite Forming Process Based on a SiC Mold for Manufacturing Fiber Metal Laminate

The microwave composite forming (MCF) process can reduce manufacturing cost because the process time is reduced by the dielectric heating of the mold and the composite material. In a previous study, the MCF process using a commercial microwave oven with a polytetrafluoroethylene mold was applied. Disadvantages of the previous MCF process have been investigated. These included the difference in tensile properties according to the cutting location, absence of a method to measure temperature during the MCF process, and the fact that the input power cannot be controlled according to the temperature. To solve these problems, a microwave oven with a silicon carbide mold was proposed in this study. Uniaxial tensile tests were conducted to obtain the tensile properties of the fiber metal laminate (FML) specimen. In addition, a microscopic image was captured to investigate the non-adhesive area. The tensile properties and thickness distribution of the FML specimens manufactured by the proposed and previous MCF processes were compared according to the cutting location of the FML sheets. Furthermore, the non-adhesive area was quantified to compare the processes. The results revealed that the proposed MCF process improved the tensile properties of the FML specimen and reduced the non-adhesive area.

HOT EXTRUSION FOLLOWED BY A HOT ECAP CONSOLIDATION COMBINED TECHNIQUE IN THE PRODUCTION OF BORON CARBIDE (B4C) REINFORCED WITH ALUMINIUM CHIPS (AA6061) COMPOSITE

A new and promising MMC approach to the reduction of pollution, greenhouse effects, and emissions is to develop a technology related to materials composite forming. Hot extrusion followed by hot ECAP is a combination of solid-state recycling method (direct recycling) that consists of chip preparations, cold compaction, and hot extrusion, followed by the ECAP process. The developed process is used to consolidate the chips for direct chip recycling purposes without the remelting phase. In this study, finished or semi-finished products from B4C-reinforced particles and AA6061 aluminium chips were produced. The samples made by hot extrusion were compared with samples obtained from hot extrusion followed by the hot ECAP process in terms of mechanical properties. Additional plastic deformation by hot ECAP after hot extrusion significantly increased the mechanical properties of the MMC compared with the samples obtained from the hot extrusion only. The density and microstructure of the samples were also determined.

Analysis and Modeling of Wrinkling in Composite Forming

Different approaches for the simulation of wrinkling during forming of textile reinforcements are presented. It is shown that 3D finite element modeling requires the consideration of an additional bending stiffness of the fibers. In shell-type modeling, the bending stiffness is important because it conditions the size of the wrinkles. Different methods to take into account the bending stiffness independently of the tensile stiffness are presented. The onset and development of wrinkles during forming is a global problem that concerns all deformation modes. It is shown in examples that the shear locking angle is not sufficient to conclude about the development of wrinkles. This article highlights the two points common to the different cases of wrinkling of continuous fiber textile reinforcements: the quasi-inextensibility of the fibers and the possible slippage between the fibers. It presents and compares different approaches to consider these two aspects. The simulation of the simultaneous forming of multilayered textile reinforcements makes it possible to see the influence of the orientation of different plies which is an important factor with regard to wrinkling.

Preparation of W-Plated Diamond and Improvement of Thermal Conductivity of Diamond-WC-Cu Composite

The tungsten (W)-plated diamond process was explored and optimized. A dense and uniform tungsten coating with a thickness of 900 nm was successfully prepared by the powder covering sintering method. The Diamond-WC-Cu composite with high density and high thermal conductivity were successfully prepared by cyclic vacuum pressure infiltration. The microstructure and composition of the W-plated diamond particles were analyzed. The effect of tungsten coating on the microstructure and thermal conductivity of the Diamond-WC-Cu composite was investigated. After calculation, the interface thermal resistance of the composite forming the tungsten carbide transition layer is 2.11 × 10−8 m2∙K∙W−1. The thermal conductivity average value of the Diamond-WC-Cu composite with a diamond volume fraction of 60% reaches 874 W∙m−1∙K−1, which is close to the theoretical prediction value of Hasselman-Johnson (H-J) model and differential effective medium (DEM) model. Moreover, the Maxwell-Eucken (M-E) model, H-J model, and DEM model were used to evaluate the thermal conductivity of the Diamond-WC-Cu composite.

Manufacturing of a 3d Finned Tube for Enhanced Boiling and Condensation Using Rolling-cutting-extruding Composite Forming

3D finned tube is a high efficient enhanced heat transfer element and its manufacturing has always been the focus of research’s attention. It is a challenging job to manufacture a 3D finned tube that can enhance both boiling and condensation because the enhanced boiling structure is completely different from the enhanced condensation structure due to different heat transfer enhancement mechanisms. An innovative rolling-cutting-extruding composite forming method is developed to realize the manufacture of a staggered stepped lattice finned tube (SLFT) with helical fins, two layers of staggered stepped lattice fins and inner helical threads, which can enhance boiling as well as condensation heat transfer. The three skewed rolling-cutting tools specially designed are uniformly distributed around the base tube and the kinematics conditions of rolling-cutting-extruding process is analyzed. The relative plunge depth of a rolling blade can’t exceed a certain limit value and the feeding angle has to be equal to the helix angle of outer helical fin. According to the kinematic conditions, the parameters of the rolling-cutting tool are selected and processing experiments of the SLFT are conducted.