ALGOR FEA HELPS THE LEE COMPANY AVOID COSTLY PROTOTYPES

To say that design optimization is critical to The Lee Company of Westbrook, Connecticut, would be an understatement. The company designs and manufactures miniature fluid control components for industries such as aerospace, scientific instrumentation and ink jet printing. The design of these components must meet tough criteria for both performance and reliability.

Philip Morgan, senior project engineer with The Lee Company's Research and Development department, recently utilized Algor Finite Element Analysis (FEA) software in the design of a seat for a hydraulic relief valve. The valve is part of a high-pressure shock absorber system and will flow 100 gallons of hydraulic oil per minute with a 5000 psi pressure drop.

Philip Morgan, Lee Company senior project engineer, works on the model he created to test the design of a seat for a high-pressure hydraulic relief valve. The FEA analysis eliminated the need for a costly prototype.

High Pressure Application

The shock suppression system is designed for use in high-pressure military and industrial applications. These include landing gear and aircraft carrier arrestor hooks, which catch incoming planes as they land.

"Our customer supplied us with an allowable space envelope that the valve had to fit into and also with stringent flow requirements," explains Mr. Morgan. "As such, a high performance valve had to fit into a small package."

Once the basic shape of the seat was determined, Mr. Morgan began performing stress analyses to make sure the geometry would hold up to the loads imposed by pressure levels as high as 15,000 psi.

Initial Analysis

"Initially, 2-D axisymmetric models were run to quickly check if the design was on the right track, " says Mr. Morgan. "Then, 3-D quarter-symmetry models were run for detailed analysis.

"As a result of the analyses, it was decided that the seat had to be stiffer and the material would have to be a high strength stainless steel, rather than a standard austenitic stainless. The shape of the seat was refined to stiffen it, and a prototype was fabricated. Using Algor probably saved us from making an unnecessary prototype which would have cost a few thousand dollars and taken two to three months to fabricate, assemble and test."

The 3-D model Mr. Morgan constructed for the analyses contains 2868 nodes and 2176 elements. The analyses were performed on a Northgate 80386, 33MHz desktop system with an 80387 coprocessor, 4 MB of RAM, a 200 MB hard drive and VGA graphics. Hard copies of the results were produced on a Hewlett-Packard Paint Jet printer. Mr. Morgan uses the "Hyper" version of the Algor software which directly utilizes extended memory, greatly enhancing the speed of the analyses.

3-D model of seat for miniature hydraulic relief valve is shown. The model contains 2868 nodes and 2176 elements.

Mr. Morgan has utilized Algor software in a large number of design applications. In his words: "I use Algor frequently to check the design of valve components and test fixtures. I have also used Algor to examine the distortion of core tubes and valve seats in miniature solenoid valves, and stress concentrations in plug bosses resulting from press fit pressures. In this latter application, gap elements and boundary elements with variable stiffnesses allow me to realistically model the problem."

SuperView is Best

"The best feature of Algor is SuperView," he continues. "It allows me to quickly visualize the results of the analysis. The graphics within SuperView make precise pictures that can be easily interpreted by anyone interested in the design, even if they are not familiar with Algor. With Pizazz Plus and a color printer, SuperView produces effective and persuasive hard copies which I have used many times at meetings and design reviews."