The assignment is to right a lab report on Torsional Deflection of Shafts using the lab experiments results.
I have attached a model paper of what the university is looking for, I have also attached the marking scheme and criteria and the structure of how the paper should be.
The lab report also needs to include graphs and tables which are in the lab results sheet.
I have added some pictures that could be included.
I have added the pictures of the results but the because the pdf only had half the results.
Some Information that needs to be included is:
Introduction
Torsion testing involves the twisting of a material sample along an axis and is a useful test for acquiring information like torsional shear stress, maximum torque, shear modulus, and breaking angle of a material or the interface between two materials.
Torsional testing can help the engineer identify an appropriate material that will possess the required torsional strength while also contributing to the goal of achieving a minimum weight. For example, in automotive and aerospace applications, Engineers will look for the lightest weight material that meets the required mechanical properties to maximise fuel efficiency and emissions legislation. This leads to the development of high strength aluminium, titanium, alloys and composites. The use of generative designs using AI CAD software can further optimise the strength to weight ratio of the selected materials.
Many finished products are subjected to torsional forces during their operation. In physics, you can calculate modulus of rigidity G, using a formula. The turning or twisting force that causes torsion is called torque.
Context and Application
Understanding torsional deflection is important in design engineering and results can be predicted and simulated in software. For example, a chassis engineer will determine the torsional deflection of the vehicle chassis and add support structures exactly where necessary to improve rigidity:-
Torsional testing machines are used to simulate real life service conditions and to check product quality against specification. There are a wide variety of machines to suit a wide variety of products. They can be dedicated test rigs which are designed and built to test one specific product (such as the vehicle chassis above), or they can be universal laboratory machines which can be adapted using different tooling to suit many types of materials and products such as drill bits, medical devices, screws, fasteners, wire, to name just a few examples.
An application example of torsional deflection in shafts is the transmission drive shaft (also known as a propeller shaft or “prop” shaft). These are used to transfer rotational energy of a system and can be found in cars, ships and wind turbines.
In a car, the drive shaft receives a turning force at one end from the engine and experiences a load at its other end via the vehicle wheels. The turning force is called “torque” and is expressed in newton metres (N·m) or foot-pound force (ft·lbf). The twist that the drive shaft experiences is called “torsion” which is expressed in either the Pascal (Pa), typical SI unit is newtons per square metre, or in pounds per square inch (psi).
The performance of the drive shaft to withstand the twisting forces (torsional forces) is dependent on all the individual components of its construction including the input shaft, yoke, universal joint, central shaft, spline, and output shaft. For reference, the video below provides an explanation of these components and how they are used in the construction of a typical drive shaft. These components can be tested both individually or as an assembly.
Material grade, manufacturing quality, torque, load (including overload), corrosion and fatigue can all lead to the failure of a drive shaft and the engineer must factor in all of these variables into the design and test for adequate performance to ensure the drive shaft achieves the minimum performance specification for the entirety of its design life so as to avoid in-service failures
What You’ll Learn
Torsional testing is conducted to assess how a product or material will respond to the stress of repeated twisting motion. Different torsional testing profiles measure the sample’s strength, performance, and endurance when subjected to a specified tension or compression load. Equations in the lab sheet shows the ability of a circular cross-section beam or specimen to resist torsion (twisting). A higher polar moment of inertia shows that the beam or specimen can resist a higher torsion or twisting force. The diameter of the beam determines polar moment of inertia. A larger diameter gives a larger polar moment of inertia.
