CHAPTER 7 SIMULATIONS OF EXPERIMENTAL WORK PERFORMED ON COMPOSITE SPECIMENS BY USING ANSYS

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1 275 CHAPTER 7 SIMULATIONS OF EXPERIMENTAL WORK PERFORMED ON COMPOSITE SPECIMENS BY USING ANSYS 7.1 INTRODUCTION EXPERIMENTAL CONFIGURATIONS Tensile Test Compression Test Impact Test Flexure Test 285

2 276 CHAPTER 7 SIMULATIONS OF EXPERIMENTAL WORK PERFORMED ON COMPOSITE SPECIMENS BY USING ANSYS 7.1 INTRODUCTION The ANSYS Computer Aided Engineering (CAE) software program, in conjunction with, 3D Computer-Aided Design (CAD) software is used to replicate the performance of composites under loaded conditions. The software generates the results and is thus recorded in this thesis. Each test presented below indicates the tests conducted on different electroplated samples. The data to be fed as an input includes, factors such as: material properties of the body, behaviour of parts in assembled conditions, types and amount of the load applied on the body. The results of the tests provide an understanding as to how the bodies may perform under practical situations and how their design might be improved. 7.2 EXPERIMENTAL CONFIGURATIONS Tensile Test The dimensions of the tensile samples as per ASTM D638 to be tested are fed into the software. The CAD model of the specimen is shown in fig The specimen is fixed in the jaws of the testing machine and the gauge length is adjusted as 50 mm. The tensile load

3 277 is applied steadily till the specimen breaks. The tensile load values for normal, 24 hours water absorbed, and EP-ABS samples vary between 3.06 KN 4.6 KN, 2.95 KN KN and 2.4 KN 2.64 KN respectively. Fig. 7.1 Tensile test specimen (ABS) The finite element model is created by using ANSYS workbench 10 software. A solid 185 Geometry, with 8 nodes is used to mesh the geometry of the specimen. Fig. 7.2 shows the meshed model of the tensile test specimen obtained with 450 elements and 2880 nodes. The test process is simulated on the computer by running ANSYS simulation program. The testing is performed by applying the above said loads for different samples. The tensile strength obtained in ANSYS is MPa, as shown in fig This is very near to the experimental value of 27.4 MPa.

4 278 Fig. 7.2 Meshed model of the tensile test specimen (ABS) Fig. 7.3 Tensile strength distribution of ABS (EP) in MPa The variation in experimental (Exp) and FEM values is noticed to be 1.63%, 2.95%, and 1.68% for Normal (N), 24hrs water absorbed (24 hrs) and EP conditions, respectively. Comparison of experimental and FEA results of tensile strength is shown in fig. 7.4.

5 Tensile Strength, MPa ABS(Exp) ABS(FEM) Normal 24 hrs EP Condition of the Materials Fig. 7.4 Comparison of experimental and FEA results of Tensile Strength samples Compression Test The compression test is conducted according to ASTM D695 standards. The specimen is placed on the compression plates of the UTM. The compressive load is gradually applied to the specimen. The compressive load values for Normal, 24 hours water absorbed, and EP-N6 samples vary between 5.9 KN KN, KN KN and KN KN respectively. The CAD model of the compression specimen is as shown in the fig. 7.5.

6 280 Fig. 7.5 Compression test specimen (N6) The finite element model is created by using ANSYS software. A solid 185 Geometry, with 8 nodes is used for meshing of the specimen geometry. Fig. 7.6 shows the finite element model of the compression test specimen obtained with 376 elements and 165 nodes. The test process is simulated on the computer by running ANSYS simulation program. The computer simulations are performed by applying the above said loads for different samples.

7 281 Fig. 7.6 Meshed model of the tensile test specimen (N6) Fig. 7.7 Compressive strength distribution of N6 (EP) in MPa The compressive strength distribution for the specimen is shown in fig The compressive strength obtained for EP-N6

8 Compressive Strength, Mpa 282 specimen from this analysis is MPa. Its experimental value is observed to be MPa. The variation in the two values is noticed to be 1.39%. Fig. 7.8 shows the results of the tests conducted on the tensile samples by simulation in FEA and as well as, by the experimental methods Nylon6(Exp) Nylon6(FEM) Normal 24 hrs EP Condition of Materials Fig. 7.8 Comparison of experimental and FEA results of Compressive Strength samples Impact Test Finite element analysis test method for impact resistance of flat, rigid plastic specimen by means of a modified impactor (falling weight) is discussed. The test method followed is slightly modified from ASTM D5420 standard.

9 283 According to ASTM D5420, a drop of known weight descends through a tube and collides with the striker that is made to rest on the specimen under study. The weight is dropped from different heights and sometimes varying weights are dropped from fixed heights. But, in case of modified dart/drop impact test, the dart is made to directly fall on the specimen instead of falling on the striker. The details of the modified drop test have been dealt in detail in chapter 5. The geometric model is created using ANSYS software as shown in the fig A 3D structural solid 185 element with 8 nodes is used to mesh the geometry of the specimen. A refined mesh is obtained after convergence check with a total number of 648 elements having 3857 nodes as shown in fig The test simulation is conducted for samples with varying dart load and drop heights as shown in fig Fig. 7.9 Impact test specimen (N6+1%)

10 284 Fig Meshed model of the Impact test specimen (N6+1%) Fig Impact stress distribution of N6+1% (EP) in MPa

11 285 Fig Deformation due to impact in N6+1% CaSiO 3 Electroplated The impact process is simulated on the computer by using the impact load data as recorded in the actual experiment. The deformation obtained from ANSYS is mm as shown in Fig. 7.12, whereas the actual experimental value for the specimen is mm. The percentage variation is 1.7. The stress distribution is shown in fig The maximum stress obtained is MPa. The experimental value is MPa. It is observed that there is a variation of 4.16%. Comparison of experimental and FEA results is shown in fig

12 Deflection, mm N6+1%(Exp, EP) N6+1%(FEM, EP) Dart Load, N and Distance, m Fig Comparison of experimental and FEA results of Impact test samples Flexure Test The specimen geometry for 3 point flexure test as per ASTM D790 standards is shown in fig The specimen is placed as a simply supported beam and load is applied at the centre gradually. The flexure load values for Normal, 24 hours water absorbed, and EP (N6 + 3% CaSiO3) samples vary between 3.35 KN 3.9 KN, 2.8 KN 3.1 KN and 3.84 KN 4.04 KN respectively.

13 287 Fig Flexure test specimen with indenter and supports (N6+3%) The finite element model is generated using ANSYS 10.0 software. A 3D solid 185 element with 8 nodes is used for breaking the specimen body into finite elements. A refined mesh is obtained with 795 elements and 4654 nodes, which is shown in fig Specific properties for both N6 and CaSiO3 were fed as an input in database of ANSYS program, as well as standard shape of specimens. The flexural tests via FEA are performed by considering the UTS values as recorded in the test experimentally.

14 288 Fig Meshed model of the Flexure test specimen (N6+3%) Fig Flexure stress distribution of N6+3% (EP) in MPa The flexural stress distribution is shown in fig The maximum flexural strength obtained by computer analysis for EP

15 Flexural Stress, Mpa 289 specimen is MPa where as its experimental value is MPa. The variation is 0.96 %, which is within acceptable range N6+3%(Exp) N6+3%(FEM) Normal 24hrs EP Condition of materials Fig Comparison of experimental and FEA results of Flexural test samples.