### UNIT CONSISTENCY IN NASTRAN

Have you ever wondered why your results look a bit odd sometimes: are those pound forces or pound masses?!... will I get Newtons if I input millimeters?! You complete your analysis only to determine your units were wrong. If so, then this table of consistent units might help you.

 Examples of Consistant Systems of Units for Structural Analysis System of Units Input Output Length Force Elastic Modulus Mass Mass Density WTMASS Param Acceleration(1 G) Disp Force Stress 1 Metricmeter-kg m N Pa kg Kg/m3 1.0 9.807 m/sec2 m N Pa 2 Metric mm-ton mm N MPa t or Mg t/mm3 or Mg/mm3 1.0 9807 mm/sec2 mm N MPa 3 English ft-lb ft lbf psf slug slug/ft3 1.0 32.17 ft/sec2 ft lbf psf 4 English in-lb (mass) in lbf psi lbf -sec2/in lbf -sec2/in4 1.0 386.1 in/sec2 in lbf psi 5 English in-lb (force) in lbf psi lbf lbf /in3 0.00259 386.1 in/sec2 in lbf psi

NOTE:
t = Metric ton = 1000 kg = 1 Mega gram (Mg)

Jeff Bolognese
February 2008

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