ESG 316/300 Midterm Examination
March 23, 1998

Please answer the following questions as completely as possible in the time 
allotted (1 hour).  Do not forget to write your name, i.d. # and class 
section on your answer books.  Please show calculations used to find your 
answers, and label all tables, etc. carefully and clearly.  Any evidence of 
academic dishonesty will be dealt with severely, as described in CEAS and 
University guidelines on academic dishonesty.



1)  (a) (15 points) Create a Failure Mode, Effects and Criticality Analysis 
table for the rear
  view mirror assembly for a car.  Describe how the results of your 
analysis can aid in improving design reliability.

         (b) (15 points) Describe the process and the goals of the Taguchi 
method of quality control.  Briefly (one paragraph) describe how it could 
be applied to manufacturing process control of the rear view mirror 
mentioned above.
(c)     (15 points)  The hinge mechanism of the rear view mirror is 
composed of a
  piece of alloy metal subjected to repeated stresses as the mirror is 
moved or positioned.  The fatigue life of this hinge may be predicted 
(roughly) using an S-N curve.
(i)     Briefly describe what an S-N curve is, and how it can be used to 
predict fatigue life in this case.
(ii)    If you decide to choose a material with a higher ultimate tensile 
strength, how would that affect your S-N curve for this hinge?



2.   (15 points) Briefly describe how you could use a Monte Carlo 
simulation to determine the extent of a underground radioactive contaminant 
plume near a reactor building (purely theoretical).  Obviously this 
involves drilling of multiple testing wells into the ground to test the 
ground water.



3.  (a) (20 points)  You are a design engineer in charge of selecting the 
proper material for construction of an aircraft wing.  The wing will be 
subjected to an average tensile stress, , of 50,000 psi.  You should 
include a safety factor of 2.5 for the stress-handling ability of the 
material.  The inspection method used for analyzing the wing to find any 
defects can identify cracks through an acoustic imaging technique.  The 
condition for failure (removing the aircraft from service)  would be any 
crack of length greater than 0.2 inch.(0.2 = 2a)   (Assume that we are 
modeling this as a crack in the center of an infinitely wide plate of 
material.)  Using this information, and the attached table of critical 
stress-intensity factors, determine what materials would pass this go/no go 
screening for this application.  Note:  Use the lower limit for the 
critical stress-intensity factor for each class of material.

(b)  (5 points) Suppose that an internal stress of 20,000 psi is created 
during processing of these plates.  How would that change you answer?

(c)  (15 points)  Create a weighted material selection matrix for the 
materials which you found for part (a) above.  (Use at least four selection 
criteria -- you can make up values for each material for these 
criteria.  Use any method you wish for creating weighting factors).

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JQ.