Experimentation of Composite Material by Using FEA Technique

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International Journal on Theoretical and Applied Research in Mechanical Engineering (IJTARME)

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ISSN (Print): 2319-3182, Volume -6, Issue-1-2, 2017 105

Experimentation of Composite Material by Using FEA Technique

1Supriya D. Kumbhar, ²Smriti Sahu

Email: [email protected]¹, [email protected]²

Abstract— Presently, a large amount of research is going on with the objective to strengthen the technological basis for the large scale application of fiber reinforced composite materials for naval vessels and structures. Fiber reinforced composites are widely used in naval ships and aerospace, ground transport, civil infrastructure because of their high strength and stiffness, low mass, excellent durability and ability to be formed into complex shape. Naval superstructure need to be designed with confidence on the basis of modeling and failure prediction. T-joint consists of a horizontal base panel, a vertical leg panel and fillet and over laminates. The purpose of the fillet is to provide the continuity of the load transfer between the base panel and the leg. The over laminate is used to enhance the capacity of the T-joint. Reduction of weight and increasing strength of the T-joint is one of the objectives. Performance testing of composite sandwich T-joints subjected to both static and dynamic loading commonly used in large panels for naval applications becomes very important. Adhesively bonded T-joints have been extensively used in assembling sandwich structures made from glass fiber reinforced plastic skins and a balsa wood core in naval vessels.

Prototype is build for experimental validation and is validated through FEA and experimental results. The advantage of adhesive bonded joints over bolted or riveted joints is that the use of fastener holes in mechanical joints inherently results in micro and local damages to the composite laminate during their fabrication. The aim of this work is to investigate the behavior of composite T- joints used in marine applications due to variation of different parameters.

Index Terms—composite Material, Fiber Reinforced Plastic (FRP) , superstructures, laminates .

I. INTRODUCTION

The use of aluminum alloys and fiber reinforced polymer composites in the ship building industry has steadily increased. Civilian applications include not only high speed vessels but also significant parts of the superstructures of large passenger ships. Military applications include mine hunters, fast patrol craft and superstructures of larger naval ships. Recently, pioneering lightweight solutions involving such features as adhesive bonding and novel types of sandwich construction have been the focus of further research and development. Some of these developments are based on innovative use of steel as well as the more usual lightweight materials. The areas of application have been extended to include more components of conventional ships, such as moveable car decks and ramps. Generally the aims are to improve safety and increasing efficiency of fabrication and maintenance.

This paper first introduces conventional and more advanced types of lightweight structures used in the ship

building industry. Recently, in naval applications of composites (with aspects related to cost benefit assessment and survivability of naval structures), the use of adhesive bonding in superstructures of high-speed craft and passenger ships (in particular material selection, design and analysis, and application cases), and the application of laser-welded steel sandwich structures for hoistable car decks are the area of interest for researchers.

Composite materials enjoy certain advantages like high specific strength, modulus and corrosion resistance compared to metals. These advantages paved the way to extensive usage of composites in structural applications, both in military and civilian sectors. A variety of fabrication techniques are in use for fabrication of composite structures. Complex composite structures like I, T, L, H shaped structures are fabricated as a single co- cured structure or as separate sub-components and later adhesively bonded.

II. EXPERIMENTAL WORK

A. Proposed work

The objective of the project is to manufacture the T- joints and perform static tensile test on them. The strength and failure mode will be studied experimentally and by finite element analysis. For static tensile, bending and compression tests the load vs. displacement curves will be plotted.

B. Experimental Setup

Photo1. Experimental setup

C. FEM work

T-joint under tensile loading:

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a) T-joint model will be created using CAD software

CATIA V5R15.

b) A method for a finite element (FE) parameter study will be developed using available software like ANSYS 14 and used for selection of promising (strong) configuration of T-joint.

III. ADVANTAGES AND DISADVANTAGES OF FRP

An important advantage of FRP materials is that their properties can be tailored to meet the requirements of the structural application. If properly designed, FRP structures provide good strength for low weight, especially when optimized uniaxial or multi-axial fabrics are used. Also, FRP materials are readily formed into complex shapes, though it may be difficult to control the fiber directions in some cases.

FRP suffers little or no corrosion if used properly. Such materials are virtually maintenance-free, giving low running costs. Stress concentrations are less critical than with metals, provided continuous fiber reinforcements are used. Hence fatigue cracking is a less problem. Most FRP materials also have a low conductivity so that effects of fire can be more easily contained than with metal structures.

Advantages for military applications include non- magnetic properties (needed where mines are hazardous) and transparency to electromagnetic waves (except with carbon reinforcements) results FRP more suitable for use. Carbon reinforced plastics can have good absorption properties with regard to electromagnetic waves, giving good stealth properties. Advanced non- structural features such as sensors can also be readily built into FRP composites. It is also possible to provide better shock resistance with FRP than with timber, which was previously used for mine counter-measure vessels.

Additional advantages of FRP sandwich include very good flexural stiffness and strength for low weight, a high margin against catastrophic failure or penetration because of the two skins, high buoyancy, good built-in thermal insulation, and the ability to build both large and small structures without costly moulds. Sandwich structures generally allow the lowest level of stiffeners to be dispensed with, giving smooth surfaces and a compact structure. Furthermore, the skin laminates are used optimally so that relatively expensive skin materials can be used without undue cost penalty.

Disadvantages of FRP include high initial cost (except for smaller applications and items produced in large series), and in many cases a need for adequate fire protection, low elastic modulus, and low through-the- thickness strength (which can also make design of connections a complex issue.

IV. FINITE ELEMENT APPROACH

The commercial finite element package ANYSYS 14 used to analyze T-joint under tensile loading. The T- joint model created using CAD software CATIA V5R15 and ANSYS 14 is used for meshing and static analysis of T-joint assuming 2D plain stress condition.

A. GEOMETRICAL MODAL

2-dimensional geometrical model of T-joint as shows in following fig.

Fig.1- 2D model of T-joint

V. FEA WORK

A. Meshing

Fig.2 Meshed model of T-Joint B. Boundary conditions for Tensile Test

Boundary conditions are applied by using 10 load-steps, in order to simulate load increment applied as in experimental test. Applied boundary conditions as shown in fig.3

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Fig.3 Applied boundary conditions C. Applied load steps

Table 1: Applied load steps in Tensile Test Load Step No. Applied Load in N

Load Step 1 1982

Load Step 2 3964

Load Step 3 5946

Load Step 4 7928

Load Step 5 9910

Load Step 6 11892

Load Step 7 13874

Load Step 8 15856

Load Step 9 17838

Load Step 10 19820

VI. FEA RESULTS

Displacement plot for load-step-1 and 2

Displacement plot for load-step-9 and 10

VII. COMPARISON OF EXPERIMENTAL AND FEA RESULTS FOR LOAD- DISPLACEMENT CHARACTERISTIC OF

T-JOINT

A. Comparison of Experimental and FEA and Error LOAD N EXPERIMENTAL

RESULTS in mm

ANSYS RESULTS

in mm

% Error

0 0 0 0

1982 1.2 0.816 4.71%

3964 1.9 1.63 1.66 %

5946 2.6 2.45 6.1 %

7828 3.1 3.26 -4.9 %

9910 3.6 4.08 -11.8 %

11892 4.3 4.9 -12.2 %

13874 5.1 5.71 -10.7 %

15856 5.6 6.53 -14.2 %

17838 6.7 7.35 -8.8 %

19820 8.4 8.16 2.9 %

B. Comparison Curve

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VIII. CONCLUSION

As Load v/s Displacement characteristics in experiment and in FEA are closely matches, also FEA shows same failure regions, from that we conclude that we can use FEA method for designing T-Joints. This will be very help full to check different configurations of T-joint for naval application rather than going for experimental method consequently this method helps to reduce lead design time drastically as well as expenses.

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