Preform Dimensions Research Articles

A review of the formability of woven fabrics for composite materials

AbstractTextile composites are advanced materials composed of preforms combined with matrix materials. The fiber structure in the preform has a significant impact on the mechanical properties of the composite. Precise control over preform dimensions and internal fiber structural uniformity, termed ‘accurate shape control’, is essential to ensure reliable and stable composite component mechanical properties. This paper reviews current research progress on fabric deformation mechanisms, focusing on experimental characterization and numerical simulation. Experimental methods for fabric deformation include tensile, compression, bending, and shear deformation, whereas numerical methods encompass macroscopic continuum, discrete, and semi‐discrete models. The insights offered in this paper will aid a greater understanding of fabric deformation mechanisms, enabling an accurate prediction of complex shape molding and effective process parameter design, ultimately facilitating the structural design and engineering applications of textile composites.Highlights Recent trends and challenges in the study of fabric deformation mechanisms are presented. The experimental methods for fabric deformation were summarized and evaluated. Representative numerical modeling techniques and simulation methods are discussed. Some recommendations on potential future research directions are detailed.

A new method for preform dimension and influence of relevant parameters in the gear forced throughfeed rolling process

Gear rolling process is an advanced forming technology in which the rolling die extrudes the preform material to flow plastically and finally form desired gears, and the preform dimension has a decisive impact on the quality of the final formed gears. To further explore the influence of tooth-tip defects on the tooth height of the formed gears in the forced throughfeed rolling process, and ensure the quality of the formed parts, a new computational method for the preform dimension was firstly proposed. A growth coefficient model based on the effective top circle of the formed gears was also given. Then, the dependence of the effective top circle size in regard to geometric parameters and material of the formed gears such as the number of teeth, module, and pressure angle were explored by the established model and finite element analysis (FEA). Finally, the experimental results were displayed to verify the proposed computational method and theoretical model. The results show the growth coefficient increases with the increase of the number of teeth and module, and decreases as the pressure angle increases. Moreover, the material with better plastic deformation ability contributes to improving the growth coefficient. Additionally, the proposed new method and theoretical model for preform dimension calculation could be adopted in the gear rolling.

Silicon optical fiber diameter dependent grain size

In the fabrication of silicon optical fibers, there is a need to understand the dependency of the grain size of the silicon core and the processing parameters during the fabrication process. This study was undertaken to determine how the grain size in the core structure varied with changes in the fabrication parameters during drawing of the silicon optical fibers. The primary fabrication variables' changes were preform dimension and drawing speed, resulting in fibers of varying diameters in both the core and cladding regions. Grain size and orientation of the silicon core of the resultant fiber was determined using Electron Backscatter Diffraction (EBSD). Grain size was normalized to the core diameter and it was found that the grain size or the length of the grain within the core increased as the diameter of the core increased. No preferential grain orientation was observed in any of the fibers. Grain length increases as the diameter increases and the rate of cooling decreases as the diameter increases. This decrease in cooling rate reduces the nucleation rate of grains during solidification process as the fibers are being drawn.

Fly Ash Permeability During Liquid AA7075 Infiltration, as a Reutilization Method for Novel MMCs

The reutilization of waste materials into novel products is widely recognized as a challenge of high technologic interest. This investigation aims to sustain fly ash as a suitable ceramic preform for the production of MMCs by liquid metal infiltration of a high-alloyed aluminum (AA7075). The effect of a series of production parameters on the resulting microstructural homogeneity of the MMC is quantified. The influence of binder concentration preform dimension and orientation are evaluated among others. Starting materials, preform, and final product are examined by optical microscopy, SEM, EDX, and XRD indicating the developing structures and dominating phenomena throughout the manufacturing process.

Experimental study of preform reheat temperature in two‐stage injection stretch blow molding

AbstractPlastic bottles used for carbonated soft drink (CSD) packages are most commonly made from poly(ethylene terephthalate) (PET) by injection stretch blow molding (ISBM). The required bottle performance criteria vary with its application but typically include top‐load strength, burst strength, optical clarity, thermal stability, and barrier properties. An experimental study of the preform reheat temperature was carried out for a 1.5‐l PET bottle produced by a two‐stage ISBM machine. The overall temperature of the preform was changed by controlling the reheat temperature of the preform; all the other process variables and preform dimensions were kept constant. Performance of the PET bottles for differing preform reheat temperatures was measured experimentally in terms of top‐load strength, burst pressure resistance, environmental stress cracking resistance (ESCR), and thermal stability. It was observed that the ESCR values and the burst strength decreased with the increasing reheat temperature, whereas the top‐load strength increased. Thermal stability tests confirmed that high‐preform reheat temperatures had a detrimental effect on the self‐standing feature of the bottles. Decreasing the reheat temperature as low as possible, while maintaining a certain preform temperature profile, ensured high ESCR and burst strength values and prevented the concaveness at the bottom of the bottle. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Preform Design for Large-Sized Frame Forging of Ti-Alloy Based on 3-D Electrostatic Field Simulation and Geometric Transformation

Large-sized frame forging of Ti-alloy is an important forced component of aircraft. The frame forging has complicated shape which leads to great difficulties in deformation. Some defects may be produced during the forming process such as un-filling or overlapping. Preform design is an effective method for producing qualified forging. In this article, a new method based on 3-D electrostatic field simulation is proposed to design preform of a large-sized frame forging of Ti-alloy and a geometric transformation method is introduced to obtain the preform dimension. In order to select more suitable preform of large-sized frame forging, FEM software Deform-3D is employed to simulate the isothermal forming process of designed preform. Deformation uniformity index ψ is introduced as a criterion to judge the forging quality and the most appropriate preform is obtained by virtual orthogonal test design.

Calculation and Design of Parameters for Four-step 3D Braided Preform with Complex Rectangular Cross Sections

The complex rectangular configuration refers to the geometrical shape jointed by two or more rectangles together. The calculation and design of parameters for 3D braided preform with simple rectangular cross-section are not suitable for those with complex rectangular cross-section because there are special microstructures in complex shaped preform. According to the unit cell models of 3D braided preform with complex rectangular cross-section, the method for computing the amount and volume of each unit cell is presented, the equation for calculating the fiber volume fraction is derived, and the relationships between preform parameters are developed. Based on the equations and relationships established, the procedure for designing the numbers of yarns arrangement is presented from preform dimensions, yarns linear density, fiber density, and fiber volume fraction. A preform with complex rectangular cross-section is designed and produced. The procedure for designing is supported by experimental results.

Effect of heat treatment of preform on the mechanical properties of flow formed AISI 4130 Steel Tubes—a theoretical and experimental assessment

Flow forming is an advanced eco-friendly chipless metal forming process, which employs an incremental rotary point deformation technique. Flow forming offers a remarkable increase in tensile properties due to strain hardening and provides excellent dimensional accuracy and surface finish for the formed part. This paper presents the results of a study on the effect of heat treatment of preform material on the mechanical properties of the flow formed part and the validity of using empirical relations in predicting the properties of the flow formed components. The strength coefficient K and strain hardening exponent n of equation σ= Kε n are determined from stress–strain curves under different heat treatment conditions for AISI 4130 steel. The effect of cold work on mechanical properties of flow formed part for a given reduction in area (RA) is predicted using empirical relations published in literature. In order to validate the hypothesis of prediction of cold worked material properties after flow forming, a few flow forming experiments are carried out. The preform dimensions are worked out based on constant volume principle. A three pass flow forming sequence was followed and the properties are measured for about 88–90% thickness reduction. Comparison of the experimental results and the properties of the flow formed tubes predicted using empirical relations shows that empirical relations can be used for predicting the properties of flow formed tubes with reasonable accuracy. Preforms processed through hardening and tempering route give better performance. These results are used for design of performs for manufacturing of large number of high strength pressure vessels successfully.

Tackification of Textile Fiber Preforms in Resin Transfer Molding

Tackified textile fiber preforms are used widely in resin transfer molding (RTM) to produce aerospace-grade composite parts. To optimize the preforming process, a thorough understanding of many important material and process issues, such as fabric formability, preform dimension control, preform permeability, fiber wetting, and tackifier compatibility with the matrix resin, is essential. These issues are investigated based on a commercial tackifier (PT 500 from 3M). The results show that tackifier concentration, tackifier powder size, and the application conditions all play important roles in governing the moldability of tackified fiber preforms.

Application of upper bound method to the powder‐forging of cup‐shaped axisymmetric preforms for estimating punch load

AbstractThis paper is concerned with the analytic derivation of the punch load required to forge cup‐shaped axisymmetric porous preforms. Splitting the two‐dimensional preform domain into three rectangular regions, we assumed the kinematically admissible velocity fields to apply the upper bound method. According to the resulting formulas, we developed an incremental numerical algorithm for computing time‐discretized step‐wise punch loads and preform volumes. In order to illustrate the validity of the proposed estimate, we compared the numerical results obtained by the present analysis with those by the finite element simulation. From the comparison made through different preform dimensions, we observed that the present analysis expects the reliable upper bounds of process step‐wise punch loads. Copyright © 2001 John Wiley & Sons, Ltd.

Tackification of Textile Fiber Preforms in Resin Transfer Molding

Tackified textile fiber preforms are used widely in resin transfer molding (RTM) to produce aerospace-grade composite parts. To optimize the preforming process, a thorough understanding of many important material and process issues, such as fabric formability, preform dimension control, preform permeability, fiber wetting, and tackifier compatibility with the matrix resin, is essential. These issues are investigated based on a commercial tackifier (PT 500 from 3M). The results show that tackifier concentration, tackifier powder size, and the application conditions all play important roles in governing the moldability of tackified fiber preforms.

Approach to net-shape preforming using textile technologies. Part II: holes

Considering cost-effective fibre-reinforced plastic (FRP) parts manufactured by resin transfer moulding (RTM) technologies, net-shape preforms can contribute to mechanical post treatment free manufacturing, hence reducing cycle-time and cost. In addition to this, RTM specific problems, such as fibre pinching when closing the tool can be avoided. The wide range of textile technologies used for FRP parts offers various possibilities to achieve net-shape parts within the preforming process including bores or inserts (see part II). The potential of the presented technologies is evaluated and discussed. Apart from standardised testing methods, a new side-impact testing was specially designed for determining the in-plane damage-tolerance of net-shape manufactured FRP parts. Folding to net-shape shows poor quality but improves mechanical properties. Rim-protections with braided inserts or over-edge stitching technologies which provide exact preform dimensions, improved mechanical performance. Especially side-impact tolerance or in-plane damage tolerance was increased. Ultra-sonic testing was successfully applied to visualise the differences in damage tolerance and propagation between these new rim technologies.

Approach to net-shape preforming using textile technologies. Part I: edges

Considering cost-effective fibre-reinforced plastic (FRP) parts manufactured by resin transfer moulding (RTM) technologies, net-shape preforms can contribute to mechanical post treatment free manufacturing, hence reducing cycle-time and cost. In addition to this, RTM specific problems, such as fibre pinching when closing the tool can be avoided. The wide range of textile technologies used for FRP parts offers various possibilities to achieve net-shape parts within the preforming process including bores or inserts (see part II). The potential of the presented technologies is evaluated and discussed. Apart from standardised testing methods, a new side-impact testing was specially designed for determining the in-plane damage-tolerance of net-shape manufactured FRP parts. Folding to net-shape shows poor quality but improves mechanical properties. Rim-protections with braided inserts or over-edge stitching technologies which provide exact preform dimensions, improved mechanical performance. Especially side-impact tolerance or in-plane damage tolerance was increased. Ultra-sonic testing was successfully applied to visualise the differences in damage tolerance and propagation between these new rim technologies.

Satellite-mill rolling of U-shaped and H-shaped wires

The satellite mill with closed pass has been successfully applied to production of U- and H-shaped profiled wires. In this study, the influence of rolling parameters such as the pass schedule, the preform dimensions and the surface roughness of the roll groove has been investigated. It is shown that the satellite-mill rolling can form much higher ribs in products than a conventional method and has an advantage in its ability to fill the metal into roll grooves. This effect is enhanced by rougher grooves and by thicker preforms.

Dimension-control technique in the VAD process and wholly synthesised single-mode fibre preform

A preform dimension control technique in the VAD process has been developed using chemical dry etching with fluoride gas applied to silica glass particles in an oxyhydrogen flame. Wholly synthesised VAD single-mode fibre preforms have been fabricated using this technique with high adjustment accuracy of outer/core diameter ratio. These preforms have exhibited excellent structural characteristics.

Application of a Forming Limit Concept to the Design of Powder Preforms for Forging

The soundness of the metallurgical structure and the associated strength of a forged powder preform material increase with increasing lateral flow during the forging process. Unconstrained lateral flow, however, enhances the possibility of fracture during deformation. In this paper, a preform design technique is presented that provides the preform shape and dimensions for forging a part to full density with a sound metallurgical structure but without fracture. The basis of the approach is a forming limit concept developed previously for cold forming processes. Application of the technique is demonstrated through design of the preform for forging a pulley blank consisting of a flange, rim and hub.