495  Approved for public release. OTR 2020- 00294  Highlights of t he Next -Generation AIAA Moving Mechanical   Assemblies Standard  

Brian W. Gore*  and Leon Gurevich* 

Abstract  

Over the past several years, an effort has been under  way to transform the previously rele ased  AIAA S-114 (2005) standard (Moving Mechanical Assemblies for Space and Launch Vehicles) into a more  modern set of requirements to complement the way many space acquisition programs have evolved. A joint  government /industry committee of mechanisms -minded subject matter experts was formed, and the  previous standard was reviewed cover -to-cover by that committee for opportunities to make it reflect  modern- day philosophies. The actual standard, tentatively designated AIAA S -114A, has not yet been  released as of the publication of this paper, since it is currently making its way through final formatting and  the approval process, but this paper discusses the most significant changes in a general way as a preview  of what will be seen in the final release.   

Introduction  

15 years…that is a long time!  Uber and Lyft did not exist to deliver  us door -to-door yet . Instagram and  Snapchat had not yet taken over our teenagers’ lives . Even the ubiquitous iPad was still 5 years away! But  that is how long it has been si nce the AIAA standard “Moving Mechanical Assemblies for Space and Launch  Vehicles” was first released. New technologies and products, better methodologies, and smarter, more  innovative ways of performing testing and analysis have all come along in that tim e, creating the need for  a more up- to-date set of requirements to design, build, and test moving mechanical assemblies.  

This paper includes a qualitative description of the update process and the more significant changes that  resulted and will be found in the new  Moving Mechanical Assemblies (MMA) standard, tentatively and likely  designated as AIAA S -114A. After concur rence was received from AIAA to move forward with the update ,  the authors sent ou t invitations to  government and industry stakeholders in the mechanisms expertise area  to participate on a committee of such subject matter experts . That committee’s charter was to approve by  consensus the changes best suited for incorporation into the updated standard, such that it would be  the  best compromise of cost -effective requirements and guidelines to produce robust MMAs for space and  launch vehicle applications.  

Much of the MMA standard’s material in the form of requirements has been retained sinc e there was already  significant  sound work done by the previous committee that produced the 2005 version of the standard.  However, that committee did run short on time to address some shortcomings, specifically in the testing  section. As a result, the test ing section was a top priority in this update effort . It has been reformatted and  rewritten, with a goal of emulat ing the format of  SMC -S-016 (also TR-RS-2014- 00016, or formerly  MIL-STD-1540 C), “Test Requirements for Launch, Upper Stage, and Space Vehicles”  (References 1, 2,  and 3) .  

Moreover, a completely new approach to calculating force/torque margin is presented in this new revision.  It specifies reduced margins over certain characteristic  resistances that are more predictable or repeatable,   but maintains the original  margins for variable resistances such as  friction . A detailed explanation of the  process, and even a working example, are included in the new version of the standard.  

* The Aerospace Corporation, El Segundo, CA;   brian.gore@aero.org; leon.gurevich@aero.org  

Proceedings of the 45th Aerospace Mechanisms Symposium, NASA Johnson Space Center, 20 20