Case Study

Fast-paced design and analysis of an optical imaging platform

Trex Enterprises

NX integrated solutions aid rapid development of complex electronics system

 

With only 14 weeks to design and deliver a prototype laser hazard detection system, an analysis-driven solution was required to achieve a successful design first time.

Sensitive electronics, harsh environments

Trex Enterprises was contracted to develop a prototype generic Laser Hazard Detection System (gLHDS) for use on a UH-1 Huey helicopter. The system is designed to detect small cross-section hazards, including powerlines, from a distance of more than 200 yards. Image clarity at the detectors is highly dependent upon the light beam path length between the primary lens and the detectors, the target accuracy of the beam (spot tolerance), and the amount of jitter induced by vibration during operation. Trex Enterprises requested ATA Engineering, Inc.’s (ATA) support in the design of the electronics cooling system and the isolation system to mount the detector to the helicopter.

Virtual product design in an integrated environment

With a tight schedule, challenging design requirements, and no time to physically test design concepts before inclusion in the prototype, a highly integrated analysis-driven design approach was needed to ensure a successful design the first time around. The tightly integrated NX™ I-deas™ software capabilities for 3D design, associative finite element modeling, finite element analysis, and CAE data management allowed multiple design trade studies to be carried out using common data models. This greatly streamlined the design iteration process and quickly eliminated designs that had a low probability of success. The ability to easily map thermal results and boundary conditions from one model to another allowed the external and internal solutions to be decoupled, simplifying the analysis and significantly reducing the time required to analyze each cooling system design. Forced response analysis was used to quickly validate isolation system design concepts and to predict detailed transient responses under the helicopter vibration environment. Dynamic response analysis and thermal distortion results were then used in image quality parameter calculations and operational clarity was verified under all conditions.

Reducing schedule with integrated, capable tools

The cooling system must maintain the temperatures of all electronics (motors, lasers, detectors) below operating limits and minimize thermal distortion of the unit. The detector mount must isolate the electronics from helicopter vibration loads. Delivery of the prototype was scheduled for 14 weeks after the start date. To meet this highly aggressive schedule, ATA used the NX suite of integrated design and analysis tools in an analysis-driven design approach.

Parasolid® software models of the enclosure and electronic components were read into NX MasterFEM and thermal and dynamic analysis meshes were built on this geometry. NX Electronic System Cooling was used for all coupled fluid/thermal analyses. Cooling system design was simplified by decoupling the internal and external fluid/thermal analyses. Heat transfer coefficients from the external analysis were mapped directly to the internal model. Associativity with the solid geometry allowed changes in baffle locations to be quickly implemented in the thermal analysis mesh. Temperature results were mapped automatically to a structural model to predict thermal distortion.

Modal responses of isolation system design concepts were determined using NX Model Solution. Dynamic transient response of the full assembly was evaluated using the modes and the forced response capabilities of NX Response Analysis. Modal response may also be predicted using NX Nastran® and modes passed directly to NX Response Analysis. Accelerations and displacements at key locations in the assembly were recovered, compared to allowables, and used to refine the isolation system design. The rate of change of angular displacement of the primary lens was determined from the dynamic analysis and used to verify the image clarity (amount of jitter).

Driving successful design solutions with analysis

Tight integration of the 3D design geometry and FE mesh generation coupled with the thermal and dynamics analysis tools allowed rapid convergence to successful isolation and cooling system designs. Analysis of four major cooling system design configurations was completed in four weeks, and five different isolation system concepts were evaluated in less than five weeks. The prototype was delivered on schedule and was successfully tested on a UH-1 Huey helicopter.

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