Department of Mechanical Engineering ME EN 4000 - Engineering Design I Engineering Lab 7 Assigned: Thursday, October 19, 2006 Due: Wednesday, October 25, 2006, 1:00PM, to the ME4000 basket in 2110 MEB Introduction The creation of complex features such as the shape of an airfoil, a helical springs, or other irregularly shaped bodies are difficult to achieve using the sketching tools available within Pro/ENGINEER or SolidWorks. In such cases, it is beneficial to generate the data that drives the creation of a feature outside of the CAD environment. This is particularly true if the feature can be described using a set of equations. This lab explores the creation of a complex feature using a Matlab script, though you could also use Excel, Mathcad, Maple, Mathematica… since the end goal is simply to create a tab delimited text file that will be imported into the solid modeler. Importing Datum Curves into Pro/ENGINEER The easiest and most straight forward method of creating a complex feature is to import one or more datum curves that can be used to generate the desired feature. The file required for this operation is a tab delimited text file with the file extension .ibl (for ProE, or txt file for SolidWorks). An .ibl file lists the x-, y-, and z-coordinates of a number of points through which Pro/ENGINEER will fit a spline. SolidWorks uses a similar file, but has simpler formatting requirements since it only requires a set of x y z values on each line to represent each point. Task You are asked to design a helical spring with 10 turns. The initial radius of the spring is 25 mm which increases 25 mm per revolution. The pitch of the spring is constant and reaches a total height of 200 mm. a) Derive a set of equations that calculate the x-, y-, and z-coordinates of the spring’s trajectory. b) Using any suitable software (Matlab, Excel, Mathcad, etc.), calculate the cartesian coordinates of a sufficiently larger number of points that can be used to create a datum curve suitable as a trajectory for the feature creation in Pro/ENGINEER or SolidWorks. Note that you will do yourself a favor if the coordinate of your first point is something like 10 0 0, so that it will be easy to generate a cross-section at the origin of your curve that will be the sweep path. c) Create an ibl file (for ProE) (or txt file for SolidWorks) that contains the coordinates of the points determined in part b (see Main/Lab7 on the ME4000 wiki site). (SolidWorks uses an even simpler file with just x y z values in each row and no header). Name: Group Name: ID #:d) Create a datum curve in Pro/ENGINEER by importing the ibl file created in part c). ProE WF2 Insert → model datum → curve → from file → done → select coord system on screen → browse → open SolidWorks 04 Insert → curve → curve through xyz points → browse → ok → ok * These instructions may vary slightly for ProE WF3 and SolidWorks 2005/2006 e) Create a sweep with a constant section diameter of 20 mm. f) Print out the shaded model, write your name and student # on it, and hand it in. You may use the matlab scripts (written by Prof. Bamberg and modified this year to be alittle more intuitive and provide Matlab output in addition to the ProE compatible ibl format) that are available for download from the ME4000 wiki ProE users, download the appropriate file and use the command: helicalspring4proe(total_rotation,init_radius,delta_radius,z_step)) SolidWorks users, download the appropriate file and use the command: helicalspring4sw(total_rotation,init_radius,delta_radius,z_step) In each case, replace total_rotation,init_radius,delta_radius,z_step with numerical values (see the header of .m files for a description of variables if you use these files). * You may model something more appropriate for your project, but please check with Prof. Provancher first