Experimental Investigation Of Tensile Parameters With Online Acoustic Emission Testing On Al6061 Matrix Composites Using Stir Casting

Experimental Investigation Of Tensile Parameters With Online Acoustic Emission Testing On Al6061 Matrix Composites Using Stir Casting

aPG Student, Department of Mechanical Engineering, University College of Engineering, Nagercoil, Tamilnadu, India, Pin: 629 004.

bDepartment of Mechanical Engineering, University College of Engineering, Nagercoil,

Tamilnadu, India, Pin: 629 004

cDepartment of Mechanical Engineering, University V.O.C. College of Engineering, Thoothukudi, Tamilnadu, India, Pin: 628 008

Metal matrix composites are used in ships, aerospace, nuclear, biotechnology and sporting goods fields. In this present work an attempt has been made to investigate the metal matrix composite using Al6061 T6 as matrix reinforced with TiB2 particles and graphite particles using stir casting method. In these reinforced particles is varied by (0, 3, 6 and 12) weight

percentage of TiB2 and (0, 3, 6 and 12) weight percentage of graphite particles. The objective is to establish the damaged defects on metal matrix composites by using Acoustic Emission Technique. Fatigue test were carried out to initiation of cracks in composite materials subjected to cyclic loads. Finally the AE data were analyzed to the damage mechanism to identify the failure modes in composite material by using ANSYS software.

Keywords: Acoustic Emission, Fatigue, Metal Matrix Composites,

1. Nowadays the composite materials in engineering applications have been

   increased gradually. The main advantage of this metal matrix is good strength, hardness and more life time. Metal matrix composites which are used in aerospace, automotive and agricultural etc. Aluminum Matrix Composites (AMCs) are light weight metals titanium and its alloy are more resistant to corrosion in reducing mineral acid solution. Acoustic Emission Technique is a relatively recent entry into the field of NDT method. In this method is used to identify the failure part of the materials. It can detect the different types of defects in metals like dislocation, movement of materials, plastic formation, yield fatigue cracking, boiling friction, mechanical impacts etc.

   In this present paper is to investigate the tensile stress using online acoustic emission monitoring. These materials are made up of aluminum matrix composites with varying percentage of TiB2 and graphite particles by stir casting process. Fatigue test were also carried out for long life of the material and good strength. Tensile tests on the prepared composites were conducted along with online AE monitoring. The sound waves were created when the material will be damaged. In this

   AE signals such as HITS, Time, Amplitude, and RMS were used to analyze the tensile behavior for different combination of AlTiB2 and graphite. AE signals were analyzed by the voltage, time, power and frequency in wave forms.

2. 1. Specimen and Materials

      Metal Matrix Composites were prepared according to ASTM standard size. In this materials were prepared with Al6061 T6, varying weight percentage of TiB2 (0%, 3%, 6%, and 12%) and Graphite particles. In this matrix material provides good combination of strength. The chemical composition of aluminum matrix is 95.8 % aluminum, 0.8% Mg, 0.4% Si, 0.04% Cr, 0.15% Mn, 0.15

      %Ti, 0.15% Cu, 0.25% Zn, 0.7% Fe, and

      0.05% others.

      Fig: Al6061 T6

      Fig: TiB2 as Reinforcement

      Fig: Graphite particles

      1. Preparation of the composite

         Stir casting method was used to prepare the composite specimens. In this process, matrix alloy Al6061 was heated its melting temperature (660C-680C) to keep semi mould condition and TiB2 particles preheated at 900C. Then the preheated particles were added to the semi mould matrix with graphite by stir cast method. The stirring was continued for 7 min at average speed of 300 rpm. Finally the mould poured into the required specimen size as 16 mm diameter and 140 mm length.

         Fig: Stir Cast Setup

      2. Experimental Procedure

         Metal Matrix Composites were prepared according to ASTM standard size. In this present work, tensile tests on specimen with varying weight percentage of TiB2 and Graphite of 80 mm gauge length have been prepared. The mechanical properties of matrix material have been studied in a tension test on 16 mm diameter and 140 mm length by prepared specimen. Tensile test have been conducted on the different combinations of specimens. These test were conducted using servo controlled Universal Testing Machine. This test was performed on ductile materials to determine tensile properties.

         Fig: Tensile Test Setup

      3. Acoustic Emission

         In this AE test was conducted by Auto Sensor Testing (weight 5 gm), resonance frequency at 250 KHz. It was tested in the prepared composite materials at 65C to 175C. The Acoustic Emission sensor type is Piezoelectric Micro80 model. A 4 channel online Acoustic Emission setup was used for detect the failures in materials. In this test, AE sensor is fixed on the middle point of the specimen to analyze the failure modes in materials.

         Fig: Acoustic Emission Test specimen

         Fig: Acoustic Emission Test Setup

         AE sound waves were produced on the prepared tensile test specimen. The AE test threshold was set to 40 dB for all combination of AE specimen from the noise on breaking material. Then the acoustic datas were monitored by online AE setup.

      4. Fatigue Test Setup

      In this Fatigue test was done by INSTRON Servo Hydraulic machine for testing specimen subjected to cyclic loadings. If a material is repeatedly loaded and unloaded at say 85% of its yield strength, it will ultimately fail in fatigue if it is loaded through enough cycles. In this test

      125 MPa stress was applied to all combination of specimen. Then the test was done by fluctuating loads.

      Fig: INSTRON Servo Hydraulic setup

3. 1. Effect of Tensile test

      The tension test was conducted to

      determine the tensile properties by the prepared specimen. The results of tensile

      test are shown below. Table 1: Tensile Test Result (Al-TIB2)

      S I N O	DESCR IPTION	Al- 0% TiB2	Al- 3% TiB2	Al- 6% TiB2	AL- 12% TiB2
      1	Peak load (KN)	7.955	17.23 5	16.94 0	16.31 0
      2	Ultimat e stress (KN/sq. mm)	0.158	0.152	0.150	0.144
      3	Elongat ion (%)	23.25	32.25	27	26.5
      4	Breakin g load (KN)	1.495	3.650	4.765	3.945

      S I N O	DESCR IPTION	Al- 0% TiB2	Al- 3% TiB2	Al- 6% TiB2	AL- 12% TiB2
      1	Peak load (KN)	7.955	17.23 5	16.94 0	16.31 0
      2	Ultimat e stress (KN/sq. mm)	0.158	0.152	0.150	0.144
      3	Elongat ion (%)	23.25	32.25	27	26.5
      4	Breakin g load (KN)	1.495	3.650	4.765	3.945

   2. Effect of Fatigue Test

      Fatigue test was done on the prepared specimen by INSTRON servo hydraulic machine. In this test the cracks as a result of repeated stresses applied below the ultimate strength of the material. The result of Fatigue test is shown below.

      In this graph represents that the displacement is plotted in x-axis and load is plotted in y-axis. In this graph is explained the detail stresses and the properties of tension test. From this result, the yield point, maximum tensile strength, breaking strength and % of elongation were measured.

      S N O	DESCRIP TION	Al- 3%TiB2 + 3% Graphit e	Al-6% TiB2+ 6% Graphi te	Al-12% TiB2+ 12% Graphit e
      1	Peak load(KN)	8.590	8.605	17.305
      2	Ultimate stress (KN/sq.mm )	0.171	0.171	0.153
      3	Elongatio n (%)	17.50	19.0	24.0
      4	Breaking load(KN)	1.151	2.480	3.075

      Table 2: Tensile Test Result (Al-TIB2 – Graphite)

      SI N O	COMPOSITI ON	PRESSURE (MPa)	NUMBER OF CYCLES
      1	Al-0% TiB2	125	13920
      2	Al-3%TiB2	125	48037
      3	Al-6% TiB2	125	72132
      5	Al-12% TiB2	125	36420
      6	Al-3% TiB2 + 3%Graphite	125	100594
      7	Al-6% TiB2+ 6%Graphite	125	100495
      8	Al-12%TiB2+ 12%Graphite	125	45445

      SI N O	COMPOSITI ON	PRESSURE (MPa)	NUMBER OF CYCLES
      1	Al-0% TiB2	125	13920
      2	Al-3%TiB2	125	48037
      3	Al-6% TiB2	125	72132
      5	Al-12% TiB2	125	36420
      6	Al-3% TiB2 + 3%Graphite	125	100594
      7	Al-6% TiB2+ 6%Graphite	125	100495
      8	Al-12%TiB2+ 12%Graphite	125	45445

      As one would expect, the result clearly shows that a low number of cycles are needed to cause fatigue failures at high stress levels while low stress levels can result in sudden, unexpected failures after a large number of cycles.

   3. Effect of Acoustic Emission Test

      From this test, Acoustic Emission is the sound waves produced when a material undergoes stress, as a result of external force. The result of Acoustic analysis was shown in below. In this data, Time is plotted in X-axis and Hits is plotted in Y-axis. When a load is applied to the test specimen beyond its elastic limit it tends to degrade.

4. Tensile tests on composite material were performed on different combinations of specimen and analyzed by online AE monitoring. In this resonant sensor of AE in materials was analyzed the different failure

   modes based on Hits, Amplitude, Time and Counts. These parameters are used to identify the failure parts using analysis software. AE data represents the real time record of progressive damage dislocation of materials and bonding materials.

   In this fatigue tests, whereas in the results of test specimens aluminum with TiB2 the fatigue life is longer than Al6061, 3% TiB2 with 3%Graphite specimen.

   Finally the graphite reinforcement added composition of specimen has the good tensile strength, hardness and long fatigue life.

5. This work is performed under the support of Mr. S.Suresh, Department of mechanical Engineering, University College of Engineering, and Nagercoil. The AE test was successfully carried out under the supervision of Dr. Karthikeyan, Department of manufacturing Engineering, Annamalai University, and Chidambaram for their useful guidance.

1. Gregory N. Morscher, Andrew L. Gyekenyesi1. The velocity and attenuation of acoustic emission waves in SiC/SiC composites loaded in tension. Composites Science and Technology 62 (2002) 11711180.

2. M. RMili, M.Moevus,N.Godin Statistical fracture of E-glass fibers using a bundle tensile test and acoustic emission monitoring Composites Science and Technology 68 (2008) 18001808.

3. Dmitry S. Ivanov a, Stepan V. Lomov a, Alexander E. Bogdanovich b, Mehmet Karahan c, Ignaas Verpoest a. A comparative study of tensile properties of non-crimp 3D orthogonal weave and multi-layer

   plain weave E-glass composites. Part 2: Comprehensive experimental

   results Composites: Part A 40 (2009)

   11441157

4. T. Sasikumar a, S. RajendraBoopathy b, K.M. Usha c,

   E.S. Vasudev. Failure strength prediction of unidirectional tensile coupons using acoustic emission peak amplitude and energy parameter with artificial neural networks. Composites Science and Technology 69 (2009) 11511155

5. Gregory S. Kellya, Suresh G. Advania,,1, John W. Gillespie Jra,2, Travis A. Bogettib.

   Contents list a model to characterize acoustic softening during ultrasonic consolidation. Journal of Materials Processing Technology 213 (2013)

   1835 1845.

6. Jianguo Yu a, Paul Ziehl a, Fabio Matta a, Adrian Pollock b. Acoustic emission detection of fatigue damage in cruciform welded joints. Journal of Constructional Steel Research 86 (2013) 859.

7. Kristián Máthis a,n, GergelyFarkas a, Milo Janeek a, HeemanChoe b. Acoustic emission study of MgAl Sr alloy reinforced with short Saffils fibers deformed in compression. Materials science&EngineeringA575 (2013)15.

8. M. Kempfa,_, O. krabalaa, V. Altst¨adta. Acoustic emission analysis for characterization of damage mechanisms in fiber

   reinforced thermosetting polyurethane and epoxy.

9. D.G. Aggelis, S.Verbruggen, E.Tsangouri, T. Tysmans, D. Van Hemelrijck. Characterization of mechanical performance of concrete beams with external reinforcement

   by acoustic emission and digital image correlation. Construction and Building Materials 47 (2013) 1037

   1045.

10. R.S. Rana Rajeshpurohit, and S.Das. Review of recent studies in Al matrix composites. International journal of scientific and Engineering Research,Vol.3,2012,ppl-16

11. Carlo Santulli. Matrix cracking Detection by Acoustic Emission in polymer composites and Counts/Duration ratio.2012,ppl-8

12. Andreas J, Brunner, Thomas tannert and Till vallee. Waveform analysis of Acoustic emission monitoring of tensile tests on welded wood-joints. Swiss Federal laboratories for Material Science and Technology, Vol.4, 2010, ppl-6.

13. https://www.google.co.in/

14. http://www.azom.com

15. http://en.wikipedia.org/wiki/Compos ite_material

16. http://en.wikipedia.org/wiki/Acoustic

    _emission

17. http://en.wikipedia.org/wiki/Fatigue_ (material)

18. http://en.wikipedia.org/wiki/Tensile_ testing