Model Steam Engine Assembly: Design and Analysis

05-05-2009, Past Projects, Muhhamad M. Raza

  1. Download the SolidWorks drawing file here
  2. Download the SolidWorks drawing file here


[1] “Roark’s Formulas for Stress and Strain”, 7th Ed. Young, Budynas, 2002

[2] “Mechanical Engineering Design”, 7th Ed. Shigley, et. al Mischke, 2004


The objective over the course of the class was to hone our skills in solidworks™ and COSMOSDesignSTAR™ in order to analyze a steam engine provided by Dr. Kevin Anderson.  The objective of the project was not simply to analyze the steam engine assembly, but also to apply what was learned through the course work.  The values that were provided were a power output of 0.5 Hp and an acceptable range for the efficiency of 0.3 to 0.6.  Furthermore a boiler pressure of 200 psi was given.  The thermodynamic expansion of the water vapor was assumed to be isobaric and a pure vapor.  The analysis was carried out in the campus laboratory (room 17-2660). For the purposes of supporting the generated stress and displacement data from COSMOSDesignSTAR™ hand calculations were required. For parts which contained complex geometry a hand calculation for the order of magnitude was carried out (these calculation were of the form found in beginning mechanics courses).  The results and supporting information may be found in the results and discussion.  In the process of the ME 425 course, we have learned that computerized methods are not reliable until the results can be verified by manual calculations that agree with the mechanics of the problem, as well as the established engineering judgment from undergraduate studies.  The manual verification can at times be more of an art than a science, and was the reason why design never has just one correct answer. Engineering judgment becomes critical where manual solutions versus computerized solutions, at times, may lead to large differences in excess of 20%. Finally, the assumptions made and the boundary conditions play a large part in the correct analysis (manual or computerized) of a problem.  Only the pertinent parts were selected for analysis.  These parts were chosen because of their function, and the loads they were subjected to (based on their function).  For example, the shaft for the valve was not analyzed because it was not being subjected to any loading.