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ME 314 Quiz#6.aSpring AnalysisScopeHelical Compression springsStatic and cycling loading analysisBuckling analysisSteel material springsReview from staticsA spring has a spring constant (K) of 100 lbs/in and a free length of 5 inches. What force would compress this spring to 3 inches? F=______________A spring with K=100 N/mm is compressed such that it has a force of 20 N in it and its length is 100 mm. What force would compress this spring to 80 mm? F=___________Ordering SpringsWhat parameters do we need to specify to a spring maker to order a compression spring?What is the most common starting point for selecting (designing) a compression spring? Think about a relief valve spring, or a pencil spring, or a mountain bike spring.Given:Find: (sufficient info for ordering)Formulate the given and find for the mechanical pencil shown and measured in class: Given:Find: (sufficient info for ordering)After finding the information needed for ordering, check the following to assure the spring is adequate:Check to make sure the spring does not yield when subjected to its maximum possible compression. Factor of safety guarding against set (yielding):________Check to make sure the spring is not close to being fully shut when under maximum compression force. If this happens the pencil would not function properly. Fractional overrun to closure should be no less than 0.1. ?= ______________________Check to make sure the spring would not buckle (not a big deal in this case). Would the spring buckle? (Yes No).Design a spring for a mountain bike front suspension. Use the following design selections. Given:Wire diameter: 0.15 inCoil outer diameter: 1.17 inMaterial: A228Square ends Set removedNo move force = 20 lbs (per spring)Typical maximum force = 200 lbs (per spring)Installation length = 10 inchesLength at typical maximum force = 5 inchesDetermine:Required spring constant: ____________Free length:_______________________Number of active coils:_______________Number of total coils:__________________ (assuming no multiple fixed coils)Solid length:_______________________Can the spring go passed maximum force to solid force? (Yes No)Spring Index: ____________________Solid force:________________________Fractional run to closure:____________________ larger than 0.15? (Yes No)Shear stress at solid force:__________________________Spring Sut?_____________Spring Sys:_______________Factor of safety guarding against set (yielding):_______________Would the spring buckle? (Yes No)Find minimum and maximum shear stresses (due to Fmin and Fmax):_________ ___________Determine the mean and alternating shear stresses:______________ ______________Draw the Goodman diagram for shear stresses. Show the load point and load line.Determine the ultimate strength in shear Sus: ________________Determine the endurance limit in shear using Zimmerelli method. Ses:___________________Determine the factor of safety guarding against fatigue failure: ___________________ ................
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