Abstract

The abundance of scientific experiments is available with Instruments of Spallation Neutron Source (SNS) at Oak Ridge National Laboratory in Tennessee. Each Instrument generally represents a set of engineering components, lined-up to pass the neutron beam through them until it finally reaches detector. Many of such components have vacuum inside and input/output aluminum windows which must be thin enough to not obstruct the neutron beam passing through. The thin windows, on the other hand, must reliably hold the atmospheric pressure from outside not compromising the safety of instrument operation. Insufficient strength and durability of the window may cause its rupture with necessary instrument shut down for costly repairs. Two major types of windows were analyzed and optimized: clamped plane aluminum sheet and machined window with fillet. To keep the stresses below safety margin at plane sheet window, the design concepts of “prestressed” and “supported” window were developed. Design of Experiment (DOE) was performed to create the response surfaces for different window design types using Isight and Abaqus software. Parametric optimization was performed next assuming that the higher stress and fatigue allowable margins will contribute to the higher robustness and reliability. To ensure that safety requirements are met, the additional plastic and fatigue analyses were completed with Abaqus and ASME recognized advanced Fe-Safe (structural fatigue) software. Results also were validated by comparing them with results for two other windows from instruments at different neutron beamlines. Performed analyses were also repeated for comprehensiveness by using solid, shell, axisymmetric shell, and membrane types of finite elements. Obtained results enabled to identify the optimal window and clamp assembly design or the possible trade-offs for the most feasible design if needed. The specifics of applied technology together with the most characteristic results will be presented. *The SNS is sponsored by the Office of Science, US Department of Energy, and managed by UT-Battelle, LLC