For much of manufacturing's history, the basic tool of engineered components was the application of analytical equations that were solved for bodies of simple geometry, such as a slender rod, a thin wall cylinder, a rectangular plate, and the like. Solutions of this type are often presented in texts, such as "Roark's Formulas for Stress and Strain," by Warren C. Young and Richard Budynas. Mathematical solutions to analytical questions for these simple shapes are exact solutions and have provided answers to many engineering problems.

Solutions to problems involving more complex shapes are very difficult and have been solved only by the use of empirical equations developed from years of experimentation and experience. For many years the use of analytical and empirical methods, in conjunction with strain gauges and other measurement techniques, has been the proven method to provide engineering solutions for real designs. But these methods usually included long development times and high research and development costs.

The Finite Element Method (FEM), developed in the first half of the 1900s, provided approximate solutions to engineering problems with complex geometries. But this method wasn't practical because it entailed solving many thousands of simultaneous equations and took months to solve by manual methods.

During the past 30 years, increased use of the computer led to huge progress in the world of design tools. Once computers became widely available, commercial Finite Element Analysis (FEA) software packages began appearing. Today, the Finite Element Method is defined as a computer-aided mathematical technique for obtaining approximate solutions to abstract equations of calculus that predicts the response of physical systems subjected to external influences. With FEA, complex geometries are represented by several thousand small elements, such as rectangular solids or trapezoidal-shaped elements. Equations defining the physical system and external influences acting on these elements can be written and solved while observing the laws of engineering disciplines.

The application of the FEM via computers has made it possible to design a component, determine its response to external forces, and run "what if" scenarios to optimize a particular design in hours as opposed to months. A prototype is then built and thoroughly tested to verify the computer design as well as other performance criteria that cannot be determined by a computer. In a large number of cases the prototype represents the final optimized design.

Over the past 20 years, AMERICAN's research engineers have embraced the use of the FEA method as well as Computer Aided Drafting (CAD) and Computer Aided Manufacturing (CAM) to make new and improved products for our customers. A recent example included feedback from our Technical Services group teaming with the Research group to improve the ease of assembly of our 14- through 36-inch Flex-Ring® pipe.

You might recall that AMERICAN used to ship our Flex-Ring® pipe in those diameters with a factory-installed, spring-loaded assembly in the restrained joint section of the pipe bell. This spring-loaded assembly was released to engage the weld spigot ring once the joint was assembled. The original design included a shipping plate, two hold-down bolts, and a heavy metal clip to keep the spring-loaded assembly "cocked" until the shipping plate was removed before joint assembly. Then the metal clip was pulled after joint assembly to release the spring-loaded assembly and engage the restraining ring.

The redesign consisted of replacing the spring-loaded assembly with a rubber-backed ring to hold the locking segments in place. Also, the pipe socket was redesigned using FEA. The net result of these efforts was fourfold: 1) a much easier joint to assemble that has received wide customer acceptance, 2) an improvement in stress distribution by putting more metal where it was needed and less where it was not needed, 3) elimination of shipping problems associated with the spring-loaded ring, shipping plate, and clip, which on occasion got knocked off or jumped out of position before the spigot was assembled into the socket, and 4) reduced assembly time for our customers and an overall improvement in productivity in manufacturing for AMERICAN.

If you have a suggestion for the improvement of our products, please let us know. Feedback from our customers and the field performance of our products provide valuable information to our design engineers, and we appreciate the opportunity to partner with you to make our industry better.