A structural dynamics analysis methodology for development of Earth entry vehicles

This paper discusses the development of an Earth entry vehicle (EEV) and the methodology to evaluate its structural dynamic response during launch and reentry. The upcoming NASA Mars Sample Return Mission (MSR) potentially planned for launch in the 2020's requires a simple and reliable method to return Martian samples back to Earth for analysis. The EEV is the proposed solution to this MSR requirement. The EEV concept is also 'multi-mission' in that the basic structural design can be be tailored for other missions beyond MSR with different payload and mission parameters but with the same goal of safely transfering a durable payload safely from outerspace to a planet's surface. During launch and reentry an EEV may experience large structural loads from inertial, acoustic, vibrational, and aerodynamic sources. In an effort to decrease development time and cost, a fully parametric and automated finite element analysis methodology was developed. In contrast to typical analysis methodologies in which models are built manually using a pre-processor GUI, the developed methodology is used to build EEV models using a coding technique that allows quick changes to nearly all aspects of the model including: geometric dimensions, material properties, load and boundary conditions, mesh properties, and analysis controls. Furthermore once model parameters are defined, all required analyses can be completed automatically. Given the proper computational resources, the developed methodology can be used to rapidly generate data for thousands of potential EEV configurations. A range of analyses including quasi-static inertial, structure born vibration frequency response, random acoustic, and aeroelastic analyses were conducted. To demonstrate the parametric capabilities of the model, key geometric dimensions were varied and then all analyses were run. The results for each set of analyses are presented and compared. For the tested configurations the quasi-static load cases were determined to induce the highest stresses near the structural attachment points. In this report it is demonstrated that the developed structural analysis methodolody has great potential in facilitating a myriad of future cost-effective space and planetary exploration missions.