Bend bar quality control method for laser shock peening

Abstract

A bend bar is available for use in a quality control test for testing for a consistency of residual stress effects in a particular material using a given a laser peening process. The bar is composed of the particular material to be tested and has a bar length and a bar thickness. The particular material has a characteristic maximum stress penetration depth for compressive residual stresses that can be formed in using the given laser peening process. The bar thickness is chosen so as to be at least twice the characteristic maximum stress penetration depth. The bar has a test surface that extends parallel to the bar length and perpendicular to the bar thickness. After forming a spot pattern on the test surface using the given laser peening process, the deflection generated in the bar due to the compressive residual stresses induced by laser peening can then be measured and used as a quality control measurement.

1 - 34 . (canceled) 
     
     
         35 . A bend bar, comprising:
 (i) a particular material having a characteristic maximum stress penetration depth for compressive residual stresses formable therein by a given laser peening process;   (ii) a bar length sufficient to facilitate production of a measurable out-of-plane deflection of at least about 0.010 inches in the bend bar upon performing the given laser peening process on the bend bar; and   (iii) a bar thickness at least twice the characteristic maximum stress penetration depth,   wherein the bend bar has a single test surface extending parallel to the bar length and perpendicular to the bar thickness.   
     
     
         36 . The bend bar of  claim 35 , further comprising a mid-thickness plane extending parallel to the test surface, wherein the bar thickness is sufficient to avoid introducing compressive residual stresses induced by the laser peening process past the mid-thickness plane of the bend bar. 
     
     
         37 . The bend bar of  claim 35 , wherein the bar thickness is in the approximate range of 0.375 inches to 1.0 inch. 
     
     
         38 . The bend bar of  claim 35 , wherein the bar length is about 4.0 inches to about 12.0 inches. 
     
     
         39 . The bend bar of  claim 35 , wherein the bar length is selected so as to facilitate production of a measurable deflection of at least about 0.010 inches therein upon performing the given laser peening process thereon. 
     
     
         40 . The bend bar of  claim 35 , wherein the bend bar has a mid-thickness plane relative to the bar thickness, the mid-thickness plane extending parallel to the test surface, the bar thickness being at least 0.120 inches to avoid introducing compressive residual stresses induced by the laser peening process past the mid-thickness plane of the bend bar. 
     
     
         41 . The bend bar of  claim 35 , wherein the bar length is selected so as to facilitate production of a measurable deflection in the approximate range of 0.012 inches to 0.018 inches therein upon performing the given laser peening process thereon. 
     
     
         42 . The bend bar of  claim 35 , wherein the bar length is about 6.0 inches to about 8.0 inches. 
     
     
         43 . The bend bar of  claim 35 , wherein the bar thickness is about 0.120 inches to about 0.500 inches. 
     
     
         44 . The bend bar of  claim 35 , wherein the particular material is substantially the same as a workpiece material upon which the given laser peening process is to be applied. 
     
     
         45 . The bend bar of  claim 35 , further comprising a bar width, wherein the bar width is greater than or equal to the bar thickness. 
     
     
         46 . The bend bar of  claim 35 , wherein the given laser peening process comprises creating a spot pattern on the test surface, and wherein the spot pattern is substantially similar to a spot pattern to be applied to a workpiece material. 
     
     
         47 . A bend bar, comprising:
 (i) a particular material having a characteristic maximum stress penetration depth for compressive residual stresses formable therein by a given laser peening process;   (ii) a bar length sufficient to facilitate production of a measurable out-of-plane deflection of at least about 0.010 inches in the bend bar upon performing the given laser peening process on the bend bar;   (iii) a bar cross section selected from a group comprising circular, oval, polygonal, and irregular; and   (iv) a bar cross section thickness at least twice the characteristic maximum stress penetration depth,   wherein the bend bar has a single test surface extending parallel to the bar length and perpendicular to the bar thickness.   
     
     
         48 . The bend bar of  claim 47 , further comprising a mid-thickness plane extending parallel to the test surface, wherein the bar cross section thickness is sufficient to avoid introducing compressive residual stresses induced by the laser peening process past the mid-thickness plane of the bend bar. 
     
     
         49 . The bend bar of  claim 47 , wherein the bar cross section thickness is in the approximate range of 0.375 inches to 1.0 inch. 
     
     
         50 . The bend bar of  claim 47 , wherein the bar length is about 4.0 inches to about 12.0 inches. 
     
     
         51 . The bend bar of  claim 47 , wherein the bar length is selected so as to facilitate production of a measurable deflection of at least about 0.010 inches therein upon performing the given laser peening process thereon. 
     
     
         52 . The bend bar of  claim 47 , wherein the bar length is selected so as to facilitate production of a measurable deflection in the approximate range of 0.012 inches to 0.018 inches therein upon performing the given laser peening process thereon. 
     
     
         53 . The bend bar of  claim 47 , wherein the bar cross section thickness is about 0.120 inches to about 0.500 inches. 
     
     
         54 . The bend bar of  claim 47 , wherein the particular material is substantially the same as a workpiece material upon which the given laser peening process is to be applied.