Reinforced Plastic Research Articles

Linear and Non-linear Analysis of Fibre Reinforced Plastic Bridge Deck due to Vehicle Loads

The present work deals with linear and nonlinear static analysis of fibre reinforced plastics composite bridge deck structures using the finite element method. The nonlinear static analysis has been carried out considering geometric nonlinearity. The analysis of bridge deck has been carried out under vehicle load as specified by IRC Class B wheel load classification. The formulation has been carried out using the finite element software package ANSYS 14.0 and the SHELL281 element is used to model the bridge deck. The bridge deck has also been modeled as a plate stiffened with closely spaced hollow box sections and a computer code is developed based on this formulation. The results obtained from the present formulation are compared with those available in the published literature. A parametric study on the stiffened bridge deck has also been carried out with varying dimensions of the stiffeners under vehicle loads.

Bonding Characteristics and Flexural Stiffening Effect of Carbon Fibre Reinforced Plastics Strand Sheets Bonded to Steel Beams

Corrosion of steel structures is unavoidable and the structural performance decreases dramatically due to the corrosion. As a repairing method for corroded steel members, bonding carbon fiber sheets with resin had been developed. The purpose of this study is to propose the flexural strengthening method for steel members by using CFRP (carbon fiber reinforced polymer) strand sheets. In order to clarify the stiffening effect and the debonding characteristics of CFRP strand sheets, and to optimize the strengthening design specifications, the flexural tests using high tension steel beams strengthened with CFRP strand sheets are performed. Two cases of experiments are carried out. In Experiment 1, the result from previous research is reflected in the strengthening design. Moreover in Experiment 2, the debonding characteristics obtained from Experiment 1 are reflected. As a result, it was clarified that CFRP strand sheets have stiffening effect equivalent to the theoretical value and its debonding property is practically high enough when FRP (fiber reinforcement polymer) sheets have an appropriate bonding length.

FIBER REINFORCED POLYMER REINFORCEMENT FOR CONSTRUCTION- STATE OF THE ART REVIEW

Development of civil engineering is intimately connected to innovation in structural material. To full fill the requirement of advance infrastructure in India, modern technologies and innovative materials has started to makes its way. Structures with bar corrosion and other distresses requires repair, rehabilitation and retrofits for increase strength, durability and much more life span. Fiber reinforce plastic (FRP) reinforcements provides solution for such work due to its non-corrosive and non-magnetic nature also high strength and low weight ratio. Now a day FRP materials are used for internal reinforcement for RC structures worldwide.

Long Carbon Fibre Reinforced Plastics and Technologies

Long Carbon Fibre Reinforced Plastics and Technologies

Application of damage–plasticity models in finite element analysis of punching shear

The paper presents numerical simulations of punching shear in a reinforced concrete slab-column configuration formerly tested in the laboratory. A brief description of the test program at the University of Waterloo is reported. For the simulation, a symmetric quarter of the test configuration is employed. Full three-dimensional finite element discretized geometry is considered together with elastic–plastic reinforcement embedded as truss elements in concrete. Two regularized numerical models of concrete, formulated within elastic–plastic-damage theories, are applied. The first one, called gradient damage, is refined by an additional averaging equation where gradient enhancement involves an internal length scale. In the second one, called rate-dependent damaged plasticity model, a viscoplastic strain rate is introduced. The results for the first model implemented in FEAP and the second model from ABAQUS are discussed in detail. Different issues of numerical simulation to properly predict punching shear behaviour in the slab-column configuration are presented.

Advances in Tool Grinding and Development of End Mills for Machining of Fibre Reinforced Plastics

The extensive use of lightweight construction materials in the aerospace industry poses a great challenge for tool manufacturers. Materials like carbon fibre reinforced plastics (CFRP) are difficult to machine and therefore put high demands on cutting tools in terms of the cutting material as well as the macro- and microscopic design. In this paper two approaches for the improvement of CFRP milling processes are presented. One approach involves the optimization of the flute grinding process for cemented carbide milling tools by the use of innovative grinding wheel specifications and their influence on cutting-relevant tool features. The other approach deals with the development of ceramic end mills for CFRP machining. Investigations about the influence of different process- and tool-related parameters on the work result and process parameters are presented.

Study on the Colour Change of Fibre Reinforced Plastic by using Colourful Textile Wastes during Molding Process

Study on the Colour Change of Fibre Reinforced Plastic by using Colourful Textile Wastes during Molding Process

Nonlinear analysis of the GFRP material wheel hub

In this paper, the current bicycle wheel was replaced by the ones which composed by the wheel hub with Glassfiber Reinforced Plastic (alkali free thin-walled cylinder material, hereinafter referred to as GFRP) material and the protective components made up of rubber outer pneumatic pad. With the help of the basic theory of elastic-plastic mechanics, the finite element Nonlinear analysis of the wheel was carried out. The results show that the maximum elastic deformation of the wheel hub and the critical value of buckling failure load were restricted by the elasticity under the condition of external loads. Considering with the tensile strength and elastic modulus of the GFRP value of the material, it is demonstrated that the material is feasible to be used for wheel hub.

High Performance Machining Enabled by Adaptive Machine Components

Abstract A current drawback in high performance machining is the dynamic behavior of the machine tool. The dedicated Eigenfrequencies of the machine tool structure lead to not optimal cutting parameters due to the danger of chatter. Possibilities to overcome this drawback are on one hand the unwanted variation of the cutting parameters and on the other hand the variation of the dynamic properties of the machine tool components. The variation of the dynamic properties of these components requires high efforts and expenses. An approach to easily vary the dynamic characteristic of the machine tool is a carriage made out of Carbon Fibre Reinforced Plastic (CFRP) with adequate mass shifting by filling the built in chambers with a fluid. This leads to shifted Eigenfrequencies and therefore to optimal cutting parameters without chatter. The mass ratio between the empty lightweight machine tool carriage made out of CFRP and the one filled enables a significant frequency shift. Within this paper three issues will be addressed: first the frequency shift depending on the carriage's position will be examined, the frequency shift according to the filling strategy will be shown and finally the amplitude reduction related to the external excitation will be presented.

Cutting Forces in Milling of Carbon Fibre Reinforced Plastics

The machining of fibre reinforced composites is an important activity for optimal application of these advanced materials into engineering fields. During machining any excessive cutting forces have to be avoided in order to prevent any waste product in the last stages of production cycle. Therefore, the ability to predict the cutting forces is essential to select process parameters necessary for an optimal machining. In this paper the effect of cutting conditions during milling machining on cutting force and surface roughness has been investigated. In particular the cutting force components have been analysed in function of the principal process parameters and of the contact angle. This work proposes experimental models for the determination of cutting force components for CFRP milling.

Effect of Fibre Loading on the Flexural Properties of Natural Fibre Reinforced Polymer Composites

The use of pineapple leaf fibres as reinforcement in plastics had increased rapidly in past few years. Thus this project was conducted to determine and compare the flexural strength of pure epoxy and pineapple leaf fibres reinforced epoxy. The natural fibres were mixed with epoxy and hardener by weight percentage fibre content. The process employed to fabricate the specimens was hand lay-up and the natural fibres was oriented randomly. The dimensions of the specimens for flexure test were based on ASTM D790 respectively. The results obtained shows that 15% PALF reinforced epoxy composite achieved the highest flexural strength among the natural fibers reinforced epoxy composites.

Retrofitting of the Historic Castagnara Bridge in Padua, Italy, with Fibre Reinforced Plastic Elements

Masonry arch bridges are typically historical infrastructures that were often not designed to withstand the heavy truck traffic that they are currently carrying and therefore must be replaced by modern concrete or steel bridges. Usual methods of strengthening masonry bridges are neither simple nor economical. This paper investigates whether the application of composites in the form of either a fabric wrap or laminate strips to masonry constructions may increase the load-bearing capacity of these structures. This research project demonstrates how advanced composite materials can be used to strengthen existing masonry arch bridges in order to increase their load-bearing capacity.This paper details the methodology adopted to retrofit and repair the Castagnara masonry bridge in Padua (Italy) and the investigations related to the damage of the bridge, the retrofitting by fibre reinforced plastic (FRP) elements and the results of the consolidation. Retrofitting involves the insertion of a prestressed steel cable into the abutments, consolidating injections, bonding by FRP strips on the extrados of the deck and demolition and reconstruction of the reinforced concrete slab. Linear-elastic and non-linear dynamic analysis of the bridge have been performed. Detailed finite element models (FEM) and on-site dynamic acceleration measurements were used to evaluate retrofit performance. Results show that applying carbon fabric to the masonry bridges provides significant increases in bending and shear capacity.However, a statistically significant number of masonry structures strengthened with carbon fibres need to be tested to arrive at definitive stress modification factors.

Optimization of Laser Cutting Parameters on the Laminated Carbon Fibre Reinforced Plastics (CFRP) Composites Using DOE Technique

Nowadays, carbon fiber reinforced plastics (CFRP) composites is widely used in the aerospace industry due to its excellent mechanical properties. In laser cutting process, high powers are used to cut materials then material melts and burns leaving edges with a high quality finish. To fulfill the high demand of cutting quality, a set of laser cutting parameters of CFRP material are studied. The objective of this experiment is to obtain an optimum laser cutting parameter thus minimizing the cutting defects particularly on kerf width at the top and bottom surfaces. The analysis of process parameter was carried out using DOE, Design Expert 6.0.8. Cutting speed, pulse duration, pulse repetition rate and pulse energy were analyzed at two levels. By the optimizing the parameter setting, significant improvement in cutting quality has been achieved.

3D FEA modelling of laminated composites in bending and their failure mechanisms

This paper developed three-dimensional (3D) Finite Element Analysis (FEA) to investigate the effect of fibre lay-up on the initiation of failure of laminated composites in bending. Tsai-Hill failure criterion was applied to identify the critical areas of failure in composite laminates. In accordance with the 3D FEA, unidirectional ([0]16), cross-ply ([0/90]4s) and angle-ply ([±45]4s) laminates made up of pre-preg Carbon Fibre Reinforced Plastics (CFRP) composites were manufactured and tested under three-point bending. The basic principles of Classical Laminate Theory (CLT) were extended to three-dimension, and the analytical solution was critically compared with the FEA results. The 3D FEA results revealed significant transverse normal stresses in the cross-ply laminate and in-plane shear stress in the angle-ply laminate near free edge regions which are overlooked by conventional laminate model. The microscopic images showed that these free edge effects were the main reason for stiffness reduction observed in the bending tests. The study illustrated the significant effects of fibre lay-up on the flexural failure mechanisms in composite laminates which lead to some suggestions to improve the design of composite laminates.

Computer analysis of the different water hammer protection systems

Water hammer is defined as a pressure surge or wave caused when a fluid in motion is forced to stop or change direction suddenly. This pressure wave can cause major problems to transmission pipes.. The present study aims to investigate problems resulting from unsteady flow and then investigate the effect of using a protection device; air vessel only, surge tank only and air vessel with surge tank; to protect pipelines against water hammer. Through this work, the study is applied using Water Hammer Software Wanda V3.30. In the present study for transient condition caused by pump failure, it is found that using the proposed an air vessel as a protection device proved to be effective for prevent column separation, using of air vessel with two surge towers will not effect the total volume of protection. Increases the diameter of the pipeline reduces the surge pressures and decrease the total volume required to protect the system. Otherwise, change of pipe material type from Glass Reinforced Plastic to steel decreases the minimum pressure but does not effect the total volume required to protect the system and change of pipe material type from Glass Reinforced Plastic to concrete decreases the minimum pressure and the total volume required to protect the system. Finally found that as the air vessel volume is reduced the number of used air vessels is increased and the negative pressure of the pipe line not affected.

A critical time window for dopamine actions on the structural plasticity of dendritic spines.

Animal behaviors are reinforced by subsequent rewards following within a narrow time window. Such reward signals are primarily coded by dopamine, which modulates the synaptic connections of medium spiny neurons in the striatum. The mechanisms of the narrow timing detection, however, remain unknown. Here, we optically stimulated dopaminergic and glutamatergic inputs separately and found that dopamine promoted spine enlargement only during a narrow time window (0.3 to 2 seconds) after the glutamatergic inputs. The temporal contingency was detected by rapid regulation of adenosine 3',5'-cyclic monophosphate in thin distal dendrites, in which protein-kinase A was activated only within the time window because of a high phosphodiesterase activity. Thus, we describe a molecular basis of reinforcement plasticity at the level of single dendritic spines.

Solid and Foam of Cellulose Nanofiber Reinforced Plastic

Solid and Foam of Cellulose Nanofiber Reinforced Plastic

Evaluation of the Ford GrFRP lightweight car

In 1978, as a follow–up to the build by Ford Motor Company of a Graphite Fibre Reinforced Plastic (GrFRP) car, a test programme was conducted to answer questions relating to durability and structural rigidity, fuel economy and performance, ride, noise levels, etc. This report discusses the tests performed and attempts to interpret them in light of the material differences between steel and the composites used in the prototype car. Special emphasis is placed on the similarities and differences in body and frame stiffness and on the noise and vibration characteristics. Results of some limited crush and durability testing are also included.

Multi-Criteria Optimization Using Grey Relational Analysis in Drilling of Glass/Epoxy Polymeric Composites

Glass Fibre Reinforced Polymeric (GFRP) composite materials have been used to make several components in engineering field. This is due to their excellent mechanical properties such as high specific strength, specific stiffness, good fatigue resistance, good corrosion resistance and light weight. Drilling is the process required for these composite materials for fitting and assembly with base part which may generate delamination at entrance and exit. In drilling of GFRP composite, delamination is one of the major defect which is more responsible for the rejection of components in the final assembly of engineering parts. An experimental investigation of full factorial design performed on drilling of Glass Fibre Reinforced plastic laminates using Helical flute straight shank drill and “Brad and Spur” drill by varying the process parameters such as cutting speed and feed rate to find the optimum drilling conditions. The main objective of this paper is to optimize the drilling process parameters with consideration of multiple performances such as specific cutting pressure, power, peel-up delamination factor and push-out delamination factor. Analysis of variance (ANOVA) was carried out for estimating the percentage contribution of process parameters on drilling performance. Grey relational analysis was used in this multiple objective optimization to get damage free drilling of GFRP composite. Response table and graph are used for this analysis which shows that feed rate is the most significant factor than the cutting speed and also it indicates that delamintation free drilling can be obtained at low feed rate and low cutting speed. The result shows that drilling performance can be enhanced effectively thorough this approach.

Bond tests on tuff elements externally bonded with FRP materials

The experimental results of several bond tests on masonry blocks made of yellow tuff and bonded with different types of Fibre Reinforced Plastic (FRP) fabrics carried out by the authors are presented and analysed. The discussion of results is mainly focused on: (1) assessing the set-up reliability, (2) choosing sufficient bonded length for achieving the full bond strength, (3) estimating the efficacy of end anchoring systems, (4) evaluating the effect of a plastering layer and of the masonry strength on the debonding load. The results are analysed both in terms of global (failure modes and loads, load–displacement curves) and local behaviour (distribution of axial strains and shear stresses) aimed to evidence the different behaviour of the used fibres (carbon, glass, basalt, flax). Finally, the experimental failure loads are compared with formulations based on a ‘design by testing’ approach.