Lin Guochang

Shaping of Rollable, Singly Curved, Parabolic Shell Reflectors

A novel, rollable, singly curved, parabolic shell reflector and its nontrivial shaping method were developed. The rollable shell reflector was a monolithic thin rectangular plate with linearly varying thickness, and it was able to roll up elastically around a mandrel. A system of end moments and loads was used to shape the linearly thickness-tapered plate into a parabolic cylinder, and a mathematical model was deduced to predict the shape accuracy of the thin plate based on nonlinear beam theory. A certain parabolic cylinder reflector was analyzed by the proposed shaping method. The optimized shape accuracy agreed well with the simulation result, and it was able to meet the precision requirement. The proposed shaping method provided a promising technology for enabling a high-precision parabolic cylinder shell reflector with different apertures.

Bias tensile properties and cycle performance of aluminum coated aramid fabric for the aerostatics envelope

The aluminum coated aramid fabric is a potential envelope material for aerostatics duo to its excellent mechanical properties. Monotonous and cyclic tensile loading experiments are conducted here to investigate the mechanical behaviors of the fabric. The off-axial tensile tests are carried out initially to study the nonlinear behaviors and the anisotropic properties. Then, cycle tensile tests with different stress amplitude are conducted to study the inelastic behaviors both in warp and weft directions. Results show that the bias angle affects the tensile behaviors significantly. Both residual strains and tangent modulus increase along with the increasing of cycle numbers. The stress amplitude is another important factor in influencing the residual strain and modulus of the coated fabric.

Mechanical Parameters Determination of a Polymeric Membrane by Digital Image Correlation

Digital image correlation (DIC) is a powerful method for full-field strain test of polymeric materials and speckle pattern on the materials surface is a critical factor for the measurement accuracy. In this paper, a new speckle pattern technique is presented and used on mechanical parameter determination of a thin and soft polymeric membrane. The presented speckle pattern is generated by combination of image noise technology and film printing technique, and it is much easier to get fine speckle pattern compared with traditional spray speckle pattern technique which is a hard and time-cost work. To verify the validity of the presented speckle pattern technique, Youngs modulus and Poissons ratio are measured by presented speckle pattern and spray speckle pattern on a tensile testing machine. It is found that the measurement results by presented speckle pattern agree well with that by fine spray speckle pattern. With the presented speckle pattern technique, DIC becomes a more convenient and fast non-contact measurement technology for polymeric materials test.