Objectives 1. Examine the relationship between torque and angular deflection of a solid circular section. Examine the relationship between torsional deflection and rod length at a constant torque. Compare the torsional deflection of a solid rod and a tube with similar diameters. The apparatus for torsion experiment. As shown in Fig. The right-hand chuck connects to a load cell using an arm to measure torque. A protractor scale on the left-hand chuck measures rotation.
A thumbwheel on the protractor scale twists specimens. Sliding the chuck along the backboard alters the test specimen length.
The backboard has some formulae and data printed on it. Note this information it will be useful later. Apparatus in the structures frame. Theory As shown in Fig. Measure the diameter of both the solid steel rod and brass rods with the vernier as accurately as possible beware of a small error in the diameter! Fill the results in Table 5 and Table 6. Wind the thumbwheel down to its stop.
Position the steel rod from the right-hand side with the rubber tipped end sticking out. Line up the first mark 15mm with the left-hand chuck note the jaws of the chuck move outward as they close!
Tighten it fully using the chuck key in the three holes. Undo the four thumbnuts which stop the chuck from sliding. Slide the chuck until the last mark mm lines up with the right-hand chuck.
This procedure sets chuck using the chuck key in each of the three holes. Wind the thumbwheel until the force meter reads 0. Zero the force meter and the angle scale using the moveable pointer arm. Wind the thumbwheel so the force meter reads 5 N and then back to zero. If the angle reading is not zero check the tightness of the chucks and start again. Take readings of the angle every 1 N of force: you should take the reading just as the reading changes.
Take readings to a maximum of 5 N of force. Enter all the readings into Table 1. To convert the load cell readings to torque multiply by the torque arm length 0. Repeat the set up and procedure from Step 1 to Step 4 for the solid brass rod and enter your results in Table 2 and Table 4.
Wind the thumbwheel so that the torque is 0. Reduce the length of the solid brass rod to the next mark mm and reset. Take a reading of angle at the same torque and record in Table 3. Repeat this procedure for lengths down to mm in Table 3. Repeat Step 1 to Step 4 with the solid brass rod replaced by the hollow brass tube. Enter all the readings into Table 4. Experiment Report 1. From the results in Table 1 and Table 2, plot torque versus angle on the same graph for both solid steel rod and solid brass rod.
Comment on the shape of the graph. What does it tell us about how angle of deflection varies because of an increased torque? Name at least three applications or situations where torsional deflection would be undesirable and one application where it could be desirable or of use. Take a look at the formulas on the backboard that predicts the behaviour of the rods.
What would happen to the relative stiffness of the rod if the diameter were increased from 3 mm to 4 mm? Plot a graph of TL against J. Examine the torsion formula and explain what the value of the gradient represents. Does the value compare favourably with typical ones?
Plot a graph of angular deflection against rod length from results in Table 3. Comment on the shape of the plot. Calculate the J values for the solid brass rod and hollow brass tube.
Examine your results in Table 4 and the J values you have calculated and comment on the effect of the missing material by analyzing the results. Comment on the efficiency of designing torsional members out of tube instead of solid material. Views Total views. Actions Shares. No notes for slide. Torsional deflection 1. What is torsion? Derivation for torsional deflection of a circular shaft Assumptions 1 The material of the shaft should be homogenous and isotropic.
Assumptions 3 Surface elements of the cylinder remain straight even after twisting takes place. Assumptions 5 Length of longitudinal elements remain constant under action of external torque. Derivation Let us consider that the shaft is subjected to shear stress. Derivation Thus shear stress varies linearly with radial distance. Derivation Now to correlate shear stress with torque T let us consider a typical cross section of the solid circular shaft.
Total views 8, On Slideshare 0. From embeds 0. Number of embeds 6. Downloads Shares 0. Comments 0. Likes 0. You just clipped your first slide! Solid Mechanics. New Delhi, Tata Mcgraw-Hill.
Hartsuijker, C. Engineering Mechanics. Dordrecht, Springer. Singh, A. Mechanics Of Solids. Introduction To Structural Analysis. New Delhi, New Age International. Maitra, G. Handbook Of Mechanical Design. Blake, A. New York, Wiley.
Mechanical Engineers Data Handbook. Mechanical Engineers Data Handbook sjtyzf By chetan poojary.
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