Speaker
Description
The harness sizing for space applications is driven by derating rules, which are specified in international standards and in particular the ECSS-Q-ST-30-11C Rev 1 (2011) , “Space Product Assurance, Derating EEE Components”, relevant for a wide range of European space projects. The respective standard, concerning wire and cable derating, is based on tests conducted in the 50’s and 70’s and known to be rather conservative, resulting in significant design margins and thus unnecessarily increasing harness mass. The presentation will focus on the validation of the Spacecraft HARness Evaluator (SHARE), a new tool to perform thermal analysis and enable mass optimization of spacecraft harness wires and cable bundles. SHARE is made available to European Space Industry to support harness design optimization and derating analysis. Validation of SHARE is performed using the test data that was collected during an ESA study “Improved design and use of electrical harnesses (ESA Contract No. 4000116112/15/NL/PS) that had the objective to reassess existing spacecraft harness derating rules and promote the use of simulation tools to optimize harness sizing. Following this study an update of the respective ECSS-Q-ST-30-11C standard on EEE components derating has been initiated in 2020. Validation of SHARE is performed using two half sets of test data collected during the previous ESA study. This comprises 534 test cases in total, both single wires (417) and bundles (117). For single wire correlation the emissivity per wire is used as (the only) correlation parameter. For bundle correlation the bundle-to-enclosure radiation (scaling factor) as well as the wire-to-wire contact conduction are used as (the only two) correlation parameters. For both single wires as well as for bundles the RMS error of the overall maximum temperature is used to drive the correlation. The correlation is performed by iteratively minimizing the RMS Error by means of Black-Box optimization. This optimization approach is very well suited to optimize non-analytic problems that involve time consuming evaluations. It is concluded that, for the investigated test cases, the 68% interval and the 95% interval of the overall prediction accuracy of the maximum temperature is given by:
Single wires:
68% interval: -4.0/+4.2°C
95% interval: -9.3/+8.5°C
Bundles:
68% interval: -3.3/+3.2°C
95% interval: -9.1/+8.3°C
The validation and development of the SHARE tool is funded by ESA in the frame of the Technology Development Element (TDE) programme under ESA Contract No. 4000132783/20/NL/FE.
