In a closed die forging process, it is impossible to form complex shapes in one stage, and thus it becomes necessary to use preform dies. In the present study, Backward Deformation Method and FE simulation via ABAQUS software has been used in order to design preform die of the H-shaped parts. In the Backward Deformation Method, the final shape of the part is considered as a starting point and u...

A process is described which involves infiltration of aluminum nitrate into partially sintered (porous) zircon bodies. Infiltration kinetics were studied using infiltration curves with two distinct regions. The final infiltrated samples were sintered at 1600 °C for 2 h and yielded specimens containing the tetragonal zirconia.The experimental results show that in spite of the similar porosity of...

The paper reports on an investigation into the various aspects of closed die cold forging of polygonal powder preforms, which have been compacted and sintered from atomized powder. It is found that for certain dimensional ratios of the preform the die pressure is minimum. An attempt has been made for the determination of the die pressures developed for given geometries of the disc during the cl...

Purpose: To predict the minimum value of additional material volume for an acceptable preform product. To predict an acceptable preform product without shape defect such as unfilling in a closed-die forging operation. Design/methodology/approach: In order to reduce the number of experiments, an orthogonal array from the Taguchi’s experimental method will be utilized to design the process parame...

Traditional fibre-optic drawing involves a thermally mediated geometric scaling where both the fibre materials and their relative positions are identical to those found in the fibre preform. To date, all thermally drawn fibres are limited to the preform composition and geometry. Here, we fabricate a metre-long crystalline silicon-core, silica-cladded fibre from a preform that does not contain a...

The synthesis of a high-melting temperature semiconductor in a low-temperature fiber drawing process is demonstrated, substantially expanding the set of materials that can be incorporated into fibers. Reagents in the solid state are arranged in proximate domains within a fiber preform. The preform is fluidized at elevated temperatures and drawn into fiber, reducing the lateral dimensions and br...

OBJECTIVES Direct-filling resin composites are used in relatively small restorations and are not recommended for large restorations with severe occlusal-stresses. The aim of this study was to reinforce composites with fiber preforms, and to investigate the effects of layer thickness and configurations on composite properties. It was hypothesized that fiber preforms would significantly increase ...

In this work, fiber Bragg gratings (FBGs) are inscribed in various undoped poly(methyl methacrylate) (PMMA) polymer optical fibres (POFs) using different types of UV lasers and inscription time and their temperature and strain sensitivities are investigated. The polymer optical fiber Bragg gratings (POFBGs) were inscribed using two UV lasers: a continuous UV HeCd @325 nm laser and a pulsed UV K...

A finite element code, in modular form, has been developed to model the complete three-dimensional resin film infusion (RFI) process. The problem formulation and its analysis incorporate compaction of the anisotropic elastic porous preform, elastic deformations of the tooling components, heat transfer in the resin, flow of resin through the preform, cure kinetics of the resin, and the heat tran...

An experimental device of dry preform stamping was designed and carried out for the first stage of the RTM process. This tool was developed to test the feasibility to obtain specific double curved shape constituted with dry fabric reinforcement. Optical strain measurement can quantify defects on the composite piece. It is just enough to change the desired punch-die set of the preform. This tool...