Figure C-3. Experimental setup for tensile testing of two-dimensional 

 tie-rod head models. 



FINDINGS 



Tie-Rod Models 



The exploratory analysis of the two-dimensional tie-rod models, 

 coated with a photoelastically sensitive epoxy coating, indicates that the 

 stress concentration (as compared to the average stress level that was observed 

 in the tie rods) at the base of the tie-rod head was approximately 3 (model 2) 

 based on the calculated nominal stresses at the smallest cross section of the 

 tie rod. The stress concentrations in the other models representing feasible 

 alternatives to the tie-rod head configuration used in the acrylic pressure vessel 

 were 5 (model 1-2.1, model 3-2.0, model 4-3, model 5-2.5, and model 6-3.1). 

 It appears that if the model 1 or 3 configuration had been substituted for the 

 one used in this study, the stress raiser effect could have been substantially 

 decreased. 



81 



