[1] Lobate scarps on Mercury are the surface expression of thrust faults and are generally thought to be the result of global contraction. Our analysis indicates that these thrust faults are not uniformly distributed and exhibit non-random patterns on the imaged hemisphere. The greatest area normalized cumulative length of the faults occurs in the southern hemisphere, below 50 S. The thrust fau...

Drilling-induced delamination is among the major concerns of applying the fiber-reinforced composite materials in various industries. Core drill ossesses the advantage for reducing the delamination by distributing the drilling thrust force toward the drill periphery. The thrust force of core rill varying with the conditions in drilling carbon fiber reinforced plastic (CFRP) is experimentally in...

Flow around a marine propulsor under crashback operating condition is computed using the large eddy simulation methodology. The incompressible NavierStokes equations are simulated in a rotating frame of reference that rotates with the propulsor. A nondissipative and robust finite volume method developed by Mahesh et al. (2004) is used on unstructured grids. The simulation yields good mean value...

A computational fluid dynamics (CFD) based analysis of the propulsive forces generated by two distinct styles of arm-pulls in front-crawl as well as backstroke is presented in this Technical Brief. Realistic models of the arm pulling through water are created by combining underwater video footage and laser-scans of an arm with computer animation. The contributions of drag and lift forces on the...

The present paper addresses the aeroelastic optimization of a membrane wing. Aerodynamic optimization of a deforming wing has been done in recent work by Walker, Patil, and Canfield. The deformation shapes required for maximum thrust and thrust efficiency were calculated. In the present work, the maximum thrust for the membrane wing is calculated by optimizing the tension in the membrane so tha...

Drilling is one of the fundamental operations in metal cutting industry. Torque and thrust force has a major influence on the tool life and machining economics. The present study mainly focus on the optimization of process parameters to reduce torque and thrust force on HSS drill and to improve the tool life. Investigations are carried on different work materials such as AA 6041, AISI 1040 and ...

We investigate the use of simple aerodynamic models for the feedback control of underactuated aerial vehicles flying with large flight envelopes. Thrust-propelled vehicles with a body shape symmetric with respect to the thrust axis are considered. Upon a condition on the aerodynamic characteristics of the vehicle, we show that the equilibrium orientation can be explicitly determined as a functi...

The Direct Simulation Monte Carlo (DSMC) method is used to numerically simulate and design a micronozzle with improved performance. Thrust calculations using the DSMC method demonstrate that the coaxial micronozzles can achieve milli-Newton thrust levels with specific impulses on the order of 45 s using argon in a cold gas expansion. Improved micronozzle designs of coaxial microthrusters are al...

The paper addresses nonlinear control of an underwater robot. A way-point line of sight scheme is incorporated to following a desired path. Command signals are generated by an autopilot consisting of three fuzzy controllers. A methods of thrust distribution among propellers in the robot’s propulsion system is also proposed. Optimisation of thrust allocation is directed towards minimisation of e...

This paper considers the problem of rotating a constellation of spacecraft using on/oo thrusters such that the relative distance between the spacecraft is maintained to within a speciied tolerance. The basic idea is to resolve all of the constraints into a sphere around the desired tra-jectory of each spacecraft. As the constellation rotates, the sphere sweeps out a tube that constrains the mot...