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MIET1077 Supplementary Material 1 Introduction This document aims to elaborate on the video explanation provided by Prof Firoz Alam in regards to the six-bar linkage mechanism, which is relevant to what students need to do for their second major assessment. The first part provides a brief summary of the fundamentals discussed in the video; the second part provides a guide on how to build the mechanism using the simulation software: Working Model. A rigid body can have three types of motion: 1. Translational/Curvilinear 2. Rotational 3. General plane (combination of curvilinear and rotational motion) Identifying of links on a six-bar linkage mechanism When counting linkages, a ground is always considered Link 1 as it provides a fixed point (or anchor) for the mechanism. A mechanism can have multiple grounds so only one of them would be considered ‘link 1’. The naming order in the video is as follows: Figure 1. The naming order applied as per the explanation video. Upon inspection, the motions produced by each link can be summarised as follows: • 2 x ‘pin’ Ground (provides rotational motion; ground on the left is considered Link 1) • 1 x ‘slider’ Ground (provides translational motion) • Link 2: rotational motion (in relation to a Ground) • Link 3: general plane/complex motion (in relation to Link 2, 4 and 5) • Link 4: partial rotational motion (in relation to a Ground) • Link 5: general plane/complex motion) • Link 6: translational/linear motion (in relation to a Ground) In real-life scenarios (e.g. car engines), it is of utmost importance to be able to associate the correct motion generated by each link, in order to achieve dynamic balancing of forces within the overall system. MIET1077 Supplementary Material 2 Recreating the Linkage Mechanism based on Relative Positions The purpose of this reference guide is to provide students with the basic understanding in how to reconstruct a simulation model using a computer software, which students will need to be able to do for their second assignment. While we are using Working Model, the principles and logic used here should be applicable across any other modelling software that students decide to use (e.g. Solidworks, PTC Creo or AutoCAD Inventor etc.). A difference to note in this example is that, as we do not have the actual measurements for the model, we will need to attempt to reconstruct the model based on relative distances. However, sufficient parameters will be provided to build the model for your assignment and so this first step will not be necessary. Step 1: Establish a unit of measurement Any software that allows a ‘grid view’ mode with standardised units will do. In this case, MS Powerpoint is used with the grid spacing set to 1cm : 1cm. The colour of the original image was adjusted to make the grid more visible while preserving sufficient contrast of the linkage mechanism for determining the relative distance. Figure 2. Image of the mechanism showed in the video demonstration labelled with relative dimensions. MIET1077 Supplementary Material 3 Step 2: Approximate angles of links relative to their respective grounds Once the relative distances are determined, angles of the links can be approximated as illustrated below: Figure 3. Approximation of dimensions and angles of the mechanism. Step 3: Setup of the Working Model software Enable the grid lines for ease of referencing; the option can be found in the ‘Workspace’ under ‘View’; also change the default angle from ‘radians’ to ‘degrees’. Figure 4. Setup of the Working Model program’s ‘Workspace’ by enabling dimensional options like ‘Grid Lines’. MIET1077 Supplementary Material 4 Figure 5. Setup of the Working Model program by changing the default from radians to degrees. Step 4: Recognising with the tools required to construct the mechanism The following are the tools needed for this project. Figure 6. Label of the tools needed to recreate the six-bar linkage mechanism. The different shapes (circle, polygon and rectangle) are used to form different parts of the mechanism including the various grounds and links. The anchor is used to define fixed/immobile parts of the mechanism—i.e. the grounds. The pin joint connects objects together and provides rotational motion; the keyed slot joint connects objects together and provides translational motion by defining the ‘back object’ as the path for the ‘front object’. When the joint is inserted onto overlapping objects, the track of the joint will be always be added on to the back object. Objects inserted later will always be considered as ‘in front’ relative to objects that have been inserted earlier