/n AU الجامعــ الأسترالية AUSTRALIAN UNIVERSITY الكويت - KUWAIT Lab Worksheet Guidelines College/ Department Name Program Code and Title: Course Code and Title: College of Engineering / Mechanical Engineering EDMF15 - Diploma of Mechanical Engineering 15FMCE122- Mechanical Engineering Materials Assessment Number and Title: Experiment 5: Torsion Test Assessment Type: Assessment Location: Assessment Date: Assessment Time/Duration: Student Name: Student ID: Section (s): Assessment General Instructions: Lab Worksheet AU - Building 4 -SF/02 • • . Lab worksheets should be neat, well organized, stapled, and submitted at the end of the lab session. All questions must be answered correctly in order to meet assessment requirements. Please use black or blue pen, not pencil. If you require any assistance during the assessment, please raise your hand and the supervisor will attend to you. All skills must be demonstrated to achieve a satisfactory result. Ensure you have all required PPE for this experiment and all OH&S regulations are followed. Please return all material provided to you to their proper places and keep the lab area clean and tidy. AU Lab Worksheet Guidelines Version No. 1.0 Page 1 of 9 AU الجامعــ الأسترالية AUSTRALIAN UNIVERSITY الكويت - KUWAIT Lab Worksheet Guidelines Maximum Marks Student Marks ASSESSMENT MARKING GUIDE Question Number 1 Student Evaluation On-time Presence Lab Participation Time Management 30 2 2 1 Total Mark 35 Assessor Feedback: Assessor Name: Assessor Signature: Student Name: Date: Date: Student Signature: Experiment 5: Torsion Test AU Lab Worksheet Guidelines Version No. 1.0 Page 2 of 9 AU الجامعــ الأسترالية AUSTRALIAN UNIVERSITY الكويت - KUWAIT Lab Worksheet Guidelines Theory: Objective: The objective of this experiment is to apply torsional moment for bars with different material and find the corresponding modulus of rigidity or shear modulus. Introduction: Torsion, also known as torque, describes a moment that is acting upon an object around the same axis in which the object lies. A moment is a measurement of the propensity of a force to create motion around either a point or an axis, and is calculated as the force upon the object multiplied by the distance of the force from the chosen origin. MT=F. R Where F is the force applied and R is the radius of disk (lever arm) in this experiment. Torque applied can also be calculated using: MT = GJ La Where: MT = Torque G = modulus of rigidity L= length of the bar J = polar moment of inertia of area; J = π 32 D4 Where D is the diameter of bar cross section the resultant torsion angle; α = a2-a1 απ AU Lab Worksheet Guidelines Version No. 1.0 Page 3 of 9 AU الجامعــ الأسترالية AUSTRALIAN UNIVERSITY الكويت - KUWAIT Lab Worksheet Guidelines T₁(r) Figure 1. Torsion of a bar and measurement of the angles a 1 and a 2, right: shear stresses on the circular section The shear modulus or modulus of rigidity, G, describes the material's response to shear stress. It is a coefficient of elasticity of a substance, expressing the ratio between the force per unit area (shearing stress) that laterally deforms the substance and the shear (shearing strain) that is produced by this force. The shear modulus is a measure of the ability of a material to resist transverse deformations and is a valid index of elastic behavior only for small deformations, after which the material is able to return to its original configuration. Members in torsion are encountered in many engineering applications. The most common application is provided by transmission shafts, which are used to transmit power from one point to another. Example: The ductile material will break at 90 degrees, while the brittle material break at 45 degrees. AU Lab Worksheet Guidelines Version No. 1.0 Page 4 of 9 AU الجامعــ الأسترالية AUSTRALIAN UNIVERSITY الكويت - KUWAIT T' (b) Brittle failure Lab Worksheet Guidelines T (a) Ductile failure Figure 2. Brittle and ductile failure by torsion Modulus of rigidity calculation steps: 1. Measure the dimensions of the bar. 2. Apply torque (torsion moment) on the bar and increase it gradually. 3. Record the torque and the twist angle. 4. Plot the torque versus twist angle. 5. The linear part of this curve can be used to measure the modulus of rigidity for the bar material. Torque (N.m) 250 200 150 100 50 B 10 12 14 Angle (rad) Figure 3. Torque vs. twist angle Equipments: 1. 2 bars made by 2 different materials: round bar with full cross-section 2. 2 movable support blocks with clamping chuck for mounting of bars, 1 fixed and 1 movable support 3. 2 movable angle indicators clampable to the bar 4. Mass disk (pulley) AU Lab Worksheet Guidelines Version No. 1.0 Page 5 of 9