Aleksandr Cherniaev

Multistep Optimization of Composite Drive Shaft Subject to Strength, Buckling, Vibration and Manufacturing Constraints

Composite drive shafts are extensively used in automotive and aeronautical applications due to lightweight combined with exceptional strength and stiffness. Complexity of the drive shaft design problem associated with the need to determine rational values for multiple parameters characterizing composite material (fiber orientation angles, stacking sequence and ply thicknesses), as well as with the fact that multiple conflicting design constraints should be considered simultaneously. In this paper we approach this problem considering carbon/epoxy drive shaft design as a multistep optimization process. It includes the following steps: 1) determination of fiber orientation angles and laminate stacking sequence based on analysis of loading conditions and analytical expressions predicting buckling load and minimal natural frequency of idealized drive shaft; 2) finding rational ply thicknesses using formal optimization procedure utilizing response surface approximations and gradient-based optimization algorithm; and 3) verification analysis of the optimized configuration with the use of nonlinear buckling analysis to ensure satisfaction of stability constraint.

Fragmentation of Millimeter-Size Hypervelocity Projectiles on Combined Mesh-Plate Bumpers

This numerical study evaluates the concept of a combined mesh-plate bumper as a shielding system protecting unmanned spacecraft from small (1 mm) orbital debris impacts. Two-component bumpers consisting of an external layer of woven mesh (aluminum or steel) directly applied to a surface of the aluminum plate are considered. Results of numerical modeling with a projectile velocity of 7 km/s indicate that, in comparison to the steel mesh-combined bumper, the combination of aluminum mesh and aluminum plate provides better fragmentation of small hypervelocity projectiles. At the same time, none of the combined mesh/plate bumpers provide a significant increase of ballistic properties as compared to an aluminum plate bumper. This indicates that the positive results reported in the literature for bumpers with metallic meshes and large projectiles are not scalable down to millimeter-sized particles. Based on this investigation’s results, a possible modification of the combined mesh/plate bumper is proposed for the future study.

Conceptual Design of an “Umbrella” Spacecraft for Orbital Debris Shielding

Current protection techniques leave spacecraft vulnerable to objects between approximately 1 and 10 cm. This paper summarizes the conceptual design of a space vehicle with the objective of shielding spacecraft from objects in this range of sizes, which was made to study the feasibility of such a method for spacecraft protection. The design was divided into three stages: first, using SPH simulations, a multi-layer shield capable of defeating large projectiles was designed; next, a deployment mechanism that allowed the shield to be stored compactly for launch was designed and analyzed using a vector-based kinematics and dynamics method; finally, a general design of the service module was made. The final design has feasible dimensions for a spacecraft to be placed in Low Earth Orbit (LEO) and consists of an eight-layer shield with an umbrella-inspired deployment mechanism.