Initially curved composite tubular beams

  1. saeid Khadem Moshir

    Dear Prof. Yu,
    I have been modeling curved composite tubes using VABS. I installed iVABS but because it needs time to learn it I decided to use VABS 3.9 with ANSYS user interface to model composite tubes. 
    I use VABS to model composite curved tubes with VABS. The tubes have lay up of [-alpha/alpha] where alpha=0,15,30,45,60,90. The tubes have an inner radius of Ri=0.049 m and outer radius of Ro=0.059 m. The thickness of each layer is t=0.005 m. The tubes have initial curvatures of k2=0 (straight), 0.5  1/m  , 1,  1/m   and 1.5 1/m. The obtained cross-sectional stiffness matrices of straight and curved tubes are attached to this email. For the cases of curved tubes with k2=1.5, k2=1 and alpha=0 and 15 degree,  the diagonal stiffness constants are negative which seems to be not correct. While for the cases of alpha>15, the obtained values are completely correct. I validated the VABS results with ANSYS 3D and my solution as Pascal dimensional reduction method. 
    I appreciate it if you see the attached cross-sectional stiffness constants for different cases.
    Thank you 

  2. Wenbin Yu

    Interesting, I will take a look. Initially curved/twisted beams will have a problem using VAM, particularly if the initial curvature/twist is large.