Torsion Testing

Table of Contents Abstract3 1. 0 presentation3 2. 0 try out Design4 2. 1 Apparatus5 2. 2 Methods5 2. 3 Procedure6 3. 0 Results and Discussion7 4. 0 illusion Analysis13 5. 0 Conclusion and Recomm polish offation13 6. 0 References14 Abstract In this contortion interrogation experiment, the torsion test was evaluated as a system for calculating the torsional inflexibility (GJ), modulus of inflexibility (G) and the soak yield test (? ) for aluminium, balmy steel and typeface. The both ends of the cylindrical example are tightened to hexagonal sockets, which one is fixed to a torsion shaft and a nonher is fixed to an input shaft.By bit the input handwheel, the crook scrap has applied to produce the tortuousness until the pattern fails. In the end of the experiment, it shows that the comparison of the behaviour of malleable and brickly materials under torsion. 1. 0 Introduction The responses of metals were deal by mechanical examination to applied forces. This testing in cludes torsion, tension, hardness, fatigue, looney and stress rupture, and impact tests. deviousness occurs when any shaft is checkmateed to a torque. The torque causes the shaft to twist. This makes one of the ends to rotate relative to the other shear stress is induced on any grumpy subdivision.Besides that, torsion testing is do on materials to determine modulus of elasticity in shear, torsion yield force and the modulus of ruptures. The shearing stress at any load on a transverse cross section varies directly proportional as the outstrip from the centre of the shaft, when a simple circular solid shaft is twisted. Therefore, during twisting, the cross section is initially planar remains a monotonic and rotates solitary(prenominal) about the axis of the shaft. 2. 0 Experiment Design Figure 7 360 stage protractor scale Figure 6 Three specimen meek steel (top), brass (middle), and aluminium (bottom) after experiment.Figure 5 Three specimen nuts steel (top), brass (mid dle), and aluminium (bottom) before experiment. Figure 2 tortuosity meter Figure 3 Deflection arm, dial gauge, levelling handwheel and elongate potential meter Figure 4 Input handwheel with 6 degree protractor scale Figure 1 Torsion testing machine 2. 1 Apparatus There were only few apparatus and materials involved in this experiment, such as 1) 3 pieces of specimens (Aluminium, brass and loony steel) 2) Vernier measure 3) Torsion Testing Equipment 2. 2 Methods Firstly the apparatus was set up as shown in Figure 1.The torque meter was switched on to depart the reading appear on the screen which connected to the torsion testing machine. Three specimens was carried out, mild steel, brass and aluminium. Each specimen was placed at the hexagonal sockets and it was tightened with the deflection arm. The handwheel was turn 90 degree each condemnation to take the reading for angle of twist from the 360 protractor scale and torque from the torque meter of each specimen. Therefore, 12 r eadings were taken and evenly distributed. After taking the 12 readings, the handwheel was continuously false until the specimen was break up.By the time the specimen was riftd, this shows that the utmost torque and the maximum angle of twist of the specimen. All the readings were recorded in a table form and calculations were done using the equations shown at section Results and Discussion. 2. 3 Procedure 1. The specimen as shown in figure 2 below was used for testing. The mild steel specimen was mounted on the torsion testing machine at position no. 4. 2. It was make sure that on the specimen there was no preload. Before starting line the experiment, the hand wheel at the input of the worm set up was turned when necessary until the read out of the amplifier is cipher.There was still zero error on the amplifier. 3. Both the indicators at the input and output shaft of the worm toss was set to zero. 4. The dial gauge of the compensation unit was set to zero. 5. The rotary m otion counter was reset. 6. The hand wheel was turned through 90 and the exfoliation Reading at rick sky input was recorded in revolution(degrees) and the torque value was recorded in digital torque meter(6). 3. 0 Results and Discussion T/J = ? /R = G? /L Torsion equation TJ= G? L G=TLJ? ?=? d432 Where T = Torque applied, Nm G = shear modulus, N/mm2 J = Polar moment of inertia, mm2 ? = Angle of twist, radianL = Gauge Length, mm ? = shear stress, N/mm2 r = gas constant of the cylindrical restraint, mm J=? d432=? (5)432=61. 36mm2 1) For mild steel, for example using point (7. 25, 17) G=TLJ? =7. 25(115)61. 36 0. 2974=45. 80N/mm2 ?=TRJ=7. 25(2. 5)61. 36=0. 295N/mm2 For brass, for example using point (5. 85, 17) G=TLJ? =5. 85(115)61. 36(0. 297)=36. 95N/mm2 ?=TRJ=5. 85(2. 5)61. 36=0. 238N/mm2 2) Torsional rigidity is ratio of torque applied about the centroidal axis of a bar at one end of the bar to the resulting torsional angle, when other end is held fixed means torsional rigidity =torqueangle For mild steel, Torsional rigidity = 7. 2517=0. 26 For brass, Torsional rigidity = 5. 8517=0. 344 Therefore, torsional rigidity of mild steel is higher than brass. 3) warning Mild Steel Scale Reading at Worm gear input in Revolution (degrees) Angle of whatchamacallum of model (col. 1/62) Torque (N. m) 90 0 0. 05 180 0 0. 05 270 2 0. 05 360 4 0. 05 450 5 0. 10 540 8 0. 10 630 9 0. 10 720 10 0. 35 810 11 1. 25 900 12 2. 85 990 14 5. 00 1080 17 7. 25 Until fracture 4092 21. 05 Specimen Brass Scale Reading at Worm gear input in Revolution (degrees) Angle of Twist of Specimen (col. 1/62) Torque (N. m) 90 1 0. 05 180 4 0. 5 270 5 0. 15 360 6 0. 55 450 7 1. 00 540 8 1. 80 630 9 2. 80 720 11 3. 95 810 14 4. 95 900 15 5. 55 990 16 5. 80 1080 17 5. 85 Until fracture 1047 14. 50 Specimen Aluminium Scale Reading at Worm gear input in Revolution (degrees) Angle of Twist of Specimen (col. 1/62) Torque (N. m) 90 1 0. 05 180 2 0. 15 270 4 0. 20 360 6 0. 30 450 8 0. 45 540 9 0. 85 63 0 10 1. 40 720 11 2. 30 810 13 3. 20 900 15 4. 20 990 17 5. 25 1080 18 6. 35 Until fracture 311 13. 50 Graph of torque against angle of twist of specimen (mild steel, brass and aluminium) ) Ductility is ability to deform under waxy stress when subject to stress brittle materials absorb relatively little energy position to fracture. For ductile material, it will produce fracture surface along the plane of the maximum shear stress. For brittle material, the fracture plane is normal to the directions of tensile stress. Mild steel is the most ductile compared to brass and aluminium. Therefore, torque is the highest in mild steel. Aluminium is the most brittle compared to mild steel and brass. Therefore, torque is the lowest in aluminium. 5) Cast iron fractures more(prenominal) easily than mild steel.Mild steel need more revolution at the worm gear input to fracture the specimen. This is because cast iron is more brittle than mild steel, it is loss ductile. Cast iron has high carbon c ontent cause it to be very brittle and is weak in tension. 4. 0 Error Analysis From the results we obtained, there was a certain error happened. Firstly, the input handwheel with 6 degree protractor scale and the 360 degree protractor scale was not pointing at the zero reading. Thus, this causes zero error in the reading. Secondly, the deflection arm and levelling handwheel was tightened up with the specimen in between the shaft.However, the specimen was not really tight, which the specimen was not really sustained in the place, whereas it still turned while the handwheel was turning and the torque of the specimen was not accurate. Therefore, the readings obtained might deviate from the correct one. 5. 0 Conclusion and Recommendation To conclude, ductile materials have higher torsional rigidity, modulus of rigidity and shear yield stress and it fractures at higher value of angle of twist, whereas brittle materials have lower torsional rigidity, modulus of rigidity and shear yield s tress and it fractures at lower value of angle of twist.In this experiment, it shows that mild steel is the most ductile material while aluminium is the most brittle material compared to mild steel and brass. To improve the results, it is important to keep the diameter constant and convert the length of the material to find the mean value so it is more accurate and the zero error is eliminated to find the actual value. The torsion testing machine should be changed, as it is old and less accurate. 6. 0 References 1) science lab Handbook, Taylors University, 2012/2013. ) J. L. Meriam and L. G. Kraige, 2006, Engineering Mechanics Statics. 6th Ed. 3) http//www. scribd. com/doc/136565/Mechanics-of-Materials-Torsion-Test 4) http//www. ce. siue. edu/330L/ laboratory%20Help%20Desk/Metal%20Torsion%20Test/Metal%20Torsion. pdf 5) http//www. scribd. com/doc/50848950/4/TORSION-TEST-ON-MILD-STEEL-ROD 6) http//eng. sut. ac. th/metal/images/stories/pdf/Lab_4Torsion_Eng. pdf 7) http//encyclopedia2 . thefreedictionary. com/torsional+rigidity