Biocomposites reinforced with natural fibers: 2000–2010

Synthesis and application of epoxy resins: A review

This work is an overview of available theories and finite elements that have been developed for multilayered, anisotropic, composite plate and shell structures. Although a comprehensive description of several techniques and approaches is given, most of this paper has been devoted to the so called axiomatic theories and related finite element implementations. Most of the theories and finite elements that have been proposed over the last thirty years are in fact based on these types of approaches. The paper has been divided into three parts. Part I, has been devoted to the description of possible approaches to plate and shell structures: 3D approaches, continuum based methods, axiomatic and asymptotic two-dimensional theories, classical and mixed formulations, equivalent single layer and layer wise variable descriptions are considered (the number of the unknown variables is considered to be independent of the number of the constitutive layers in the equivalent single layer case). Complicating effects that have been introduced by anisotropic behavior and layered constructions, such as high transverse deformability, zig-zag effects and interlaminar continuity, have been discussed and summarized by the acronimC
 -Requirements. Two-dimensional theories have been dealt with in Part II. Contributions based on axiomatic, asymtotic and continuum based approaches have been overviewed. Classical theories and their refinements are first considered. Both case of equivalent single-layer and layer-wise variables descriptions are discussed. The so-called zig-zag theories are then discussed. A complete and detailed overview has been conducted for this type of theory which relies on an approach that is entirely originated and devoted to layered constructions. Formulas and contributions related to the three possible zig-zag approaches, i.e. Lekhnitskii-Ren, Ambartsumian-Whitney-Rath-Das, Reissner-Murakami-Carrera ones have been presented and overviewed, taking into account the findings of a recent historical note provided by the author. Finite Element FE implementations are examined in Part III. The possible developments of finite elements for layered plates and shells are first outlined. FEs based on the theories considered in Part II are discussed along with those approaches which consist of a specific application of finite element techniques, such as hybrid methods and so-called global/local techniques. The extension of finite elements that were originally developed for isotropic one layered structures to multilayerd plates and shells are first discussed. Works based on classical and refined theories as well as on equivalent single layer and layer-wise descriptions have been overviewed. Development of available zig-zag finite elements has been considered for the three cases of zig-zag theories. Finite elements based on other approches are also discussed. Among these, FEs based on asymtotic theories, degenerate continuum approaches, stress resultant methods, asymtotic methods, hierarchy-p,_-s global/local techniques as well as mixed and hybrid formulations have been overviewed.

Theories and Finite Elements for Multilayered, Anisotropic, Composite Plates and Shells

A review: Fibre metal laminates, background, bonding types and applied test methods

Accuracy of machined components is one of the most critical considerations for any manufacturer. Many key factors like cutting tools and machining conditions, resolution of the machine tool, the type of workpiece etc., play an important role. However, once these are decided upon, the consistent performance of the machine tool depends upon its ability to accurately position the tool tip vis-a-vis the required workpiece dimension. This task is greatly constrained by errors either built into the machine or occurring on a periodic basis on account of temperature changes or variation in cutting forces. The three major types of error are geometric, thermal and cutting-force induced errors. Geometric errors make up the major part of the inaccuracy of a machine tool, the error caused by cutting forces depending on the type of tool and workpiece and the cutting conditions adopted. This part of the paper attempts to review the work done in analysing the various sources of geometric errors that are usually encountered on machine tools and the methods of elimination or compensation employed in these machines. A brief study of cutting-force induced errors and other errors is also made towards the end of this paper.

Error compensation in machine tools — a review: Part I: geometric, cutting-force induced and fixture-dependent errors

Track links for high mobility tracked vehicles usually consist of track shoe bodies, track pins, rubber pads, end-connectors, and rubber bushings. Since the track pin is subjected to large transverse track tension from the track link, conventional track pins for high mobility vehicles are usually made of high strength steel, such as forged chrome-molybdenum steel, which increases the weight of tracked vehicles due to the high density of steel. Weight reduction has been the principal goal of many of the experimental track programs since World War II. However, great weight reduction in the track pin has not been achieved for several decades except a few experimental works. Therefore, in this paper, the axiomatic design approach was employed to design a lower weight track pin with composite materials. From the design of composite track pin, the weight reduction of 50% as well as better endurance life was achieved.

Axiomatic Design of Composite Track Pin

Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints, which can monitor continuously the damage of adhesively bonded structures without producing any defect induced by inserting a sensor. However, due to low piezoelectric properties of epoxy adhesives, the detection of micro crack was impossible. At the cryogenic temperature, the detection of micro crack is important to estimate the fatigue life because the polymeric adhesives become very brittle. Therefore, in this work, the epoxy adhesive was modified by quartz nano-particles which have much higher piezoelectric properties than the epoxy adhesives. To investigate the effects of quartz nano-particles, the static and dynamic tests of the tubular adhesive joints were performed to compare the joint strength and sensitivity of damage monitoring performance. From the experiment result, it was found that the quartz nano-particles not only improved the joint strength but also increased the sensitivity of damage monitoring performance at cryogenic temperature.

The Effect of Quartz Nano-Particles on the Damage Monitoring of Adhesive Joint at Cryogenic Temperature

PURPOSE: A composite material ball screw is provided to improve a damping efficiency by inserting a composite material shaft member into the center of the screw and to stably drive at a high speed by increasing natural frequency. CONSTITUTION: A composite material ball screw includes a hollow shaft(11) having a screw thread(15) on an outer circumference and a composite material shaft member(12) fixed in the center along an axial direction to have a space for forming sliding friction with an inner surface of the hollow shaft through the vibration. Since the composite material shaft member is fixed only at both ends of the hollow shaft, vibration energy is vanished to friction energy due to sliding friction between the inner surface of the hollow shaft and the outer surface of the composite material shaft member to make the attenuation action become large.

Ball screw with composite materials

Provided are a particle-reinforced cellular foam which has a uniform closed cell structure and exhibits markedly improved specific strength and thermal insulation performance, and a method for producing the particle-reinforced cellular foam.

Dai Gil Lee

Papers

Axiomatic Design of Composite Track Pin

The Effect of Quartz Nano-Particles on the Damage Monitoring of Adhesive Joint at Cryogenic Temperature

Ball screw with composite materials

Particle reinforced cellular foam and preparation method thereof

Axiomatic Design of Composite Hemispherical Bearing