Overlap-Stiffened Panels for Optimized Buckling Performance Under Minimum Steering Radius Constraints

Recent research on variable stiffness laminates have shown both numerically and experimentally that further improvement on the buckling behaviour is possible by incorporating overlaps that result in variable thickness profiles, with the thickness non-linearly coupled with the local steering angle. We present the concept of overlap-stiffened panels, developing a design method that allows for incorporating higher-stiffness regions into individual plies of a variable-angle tow (VAT) laminate, taking advantage of the non-linear coupling between the tow steering angles and the local thickness. The proposed method naturally copes with minimum steering radius constraints of different manufacturing processes, and the present study considers two tow steering processes: automated fiber placement (AFP) and continuous tow shearing (CTS). The minimum radius constraint is satisfied by connecting two transition regions of thickness specified on each ply by means of circular fiber tow arcs, of which the radius of curvature always exceed the minimum manufacturing constraint. Each individual ply exploring the overlap-stiffened design is described using 5 design variables. Laminates made up of these overlap-stiffened plies are optimized for a maximum volume-normalized buckling performance under bi-axial compression, measured through FEM, by a genetic algorithm and benchmarked against a straight fiber panel optimized for the same load case. The conclusion can be drawn that both AFP and CTS overlap-stiffened VAT panels can at least achieve the double of the volume-normalized buckling performance of an optimized straight fiber panel, demonstrating the potential of the proposed design method.

Experimental Test of Artificial Potential Field-Based Automobiles Automated Perpendicular Parking

Automobiles automated perpendicular parking using Artificial Potential Field (APF) is discussed in this paper. The Unmanned Ground Vehicle (UGV) used for carrying out experiments is introduced first; UGV configuration, kinematics, and motion controller are included. Based on discretized form of the parking space, the APF is generated. Holonomic path for the vehicle parking is found first; path modification to satisfy minimum turning-radius constraint is performed based on Reeds-Shepp curve connections. Optimization efforts are included to remove extra maneuvers and to reduce length of the path. Afterwards waypoints are generated as reference for the vehicle to track. Perpendicular parking tests with several different start configurations are demonstrated; based on the test results the automated parking framework proposed in this paper is considered to be effective.

CAD-Based Adjoint Shape Optimisation of a One-Stage Turbine With Geometric Constraints

An extension of the CAD-based parametrisation termed ‘NURBS-based parametrisation with complex constraints’, or NsPCC, is developed and applied to the aerodynamic shape optimisition of a one-stage high pressure turbine. NsPCC uses a test-point approach to impose various geometric constraints such as continuity, thickness and trailing edge radius constraint. To perform the shape optimisation using NsPCC, The surface sensitivity is first computed efficiently using a discrete adjoint solver. The displacements of the control points of the NURBS patches are used as the design variables and linked to the surface sensitivity through consistent application of Automatic Differentiation. A robust mesh deformation based on linear elasticity and further enhanced with sliding mesh capability is used to deform the mesh at each design step. Finally, the optimised rotor shape is exported as a STEP file. The method is demonstrated on a turbine stage where isentropic efficiency is improved by over 0.4% with both the inlet capacity and rotor reaction ratio deviation below the prescribed thresholds. Satisfaction of the G1 continuity, thickness and trailing radius constraints is verified.

RADIUS CONSTRAINT OF THE RECYCLED DOUBLE PULSAR PSR J0737-3039

We investigate the radius of the recycled pulsar in double pulsar system PSR J0737-3039. In the standard accretion spin-up model, the recycled pulsar spin up continues until arriving at a minimum spin period, or so-called "equilibrium period", which is related to the stellar magnetic field, the accretion rate and radius. The generic spin-down age may give realistic estimates for normal pulsar PSR J0737-3039B, since its present spin period is much longer than the one at birth. In this paper, we estimate the radius of millisecond pulsar (MSP) PSR J0737-3039A by assuming its true age is same as the spin-down age of its companion PSR J0737-3039B. We find that the radius of recycled pulsar PSR J0737-3039A ranges approximately from 12 to 38 km, and it should be far from the composition of strange quark matters, as shown in the mass-radius diagram.

Radius Constraint Least-Square Circle Fitting Method

Short arc usually lost the most part of information in measurement, therefore the fitting center can not be found accurately. The shortage of least-square method is analyzed in short arc fitting. The uncertainty of fitting center direction and fitting radius is illustrated. And we derived the solution to estimation of fitting center direction. Base on the testing environment, radius constraint least-square fitting circle method is proposed. Simulations demonstrated excellent performance of this algorithm.