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NAS Command Transformations

The transformation equations for the NASVEC and NASCCV commands.

Stress Transformation Equations

$$\alpha = \text{Angle between global X and local X}$$ $$t = \text{Shell thickness}$$ $$E = \text{Shell material's Young's modulus}$$ $$\nu = \text{Shell material's Poisson ratio}$$

Thin Shell

$$ S_{x_G} = S_{x_L}*cos^2(\alpha)+2*S_{xy_L}*sin(\alpha)*cos(\alpha)+S_{y_L}sin^2(\alpha) $$ $$ S_{y_G} = S_{x_L}*sin^2(\alpha)-2*S_{xy_L}*sin(\alpha)*cos(\alpha)+S_{y_L}cos^2(\alpha) $$ $$ S_{xy_G} = S_{xy_L}*(cos^2(\alpha)-sin^2(\alpha))-(S_{y_L}+S_{x_L})*sin(\alpha)*cos(\alpha) $$ $$ M_{x_G} = M_{x_L}*cos^2(\alpha)+2*M_{xy_L}*sin(\alpha)*cos(\alpha)+M_{y_L}sin^2(\alpha) $$ $$ M_{y_G} = M_{x_L}*sin^2(\alpha)-2*M_{xy_L}*sin(\alpha)*cos(\alpha)+M_{y_L}cos^2(\alpha) $$ $$ M_{xy_G} = M_{xy_L}*(cos^2(\alpha)-sin^2(\alpha))-(M_{y_L}+M_{x_L})*sin(\alpha)*cos(\alpha) $$

Thick Shell

$$ N_{x_G} = N_{x_L}*cos^2(\alpha)+2*N_{xy_L}*sin(\alpha)*cos(\alpha)+N_{y_L}sin^2(\alpha) $$ $$ N_{y_G} = N_{x_L}*sin^2(\alpha)-2*N_{xy_L}*sin(\alpha)*cos(\alpha)+N_{y_L}cos^2(\alpha) $$ $$ N_{xy_G} = N_{xy_L}*(cos^2(\alpha)-sin^2(\alpha))-(N_{y_L}+N_{x_L})*sin(\alpha)*cos(\alpha) $$ $$ M_{x_G} = M_{x_L}*cos^2(\alpha)+2*M_{xy_L}*sin(\alpha)*cos(\alpha)+M_{y_L}sin^2(\alpha) $$ $$ M_{y_G} = M_{x_L}*sin^2(\alpha)-2*M_{xy_L}*sin(\alpha)*cos(\alpha)+M_{y_L}cos^2(\alpha) $$ $$ M_{xy_G} = M_{xy_L}*(cos^2(\alpha)-sin^2(\alpha))-(M_{y_L}+M_{x_L})*sin(\alpha)*cos(\alpha) $$ $$ Q_{x_G} = Q_{x_L}*cos(\alpha)+Q_{y_L}*sin(\alpha) $$ $$ Q_{y_G} = -Q_{x_L}*sin(\alpha)+Q_{y_L}*cos(\alpha) $$

Strain Equations

$$ \varepsilon_x = \frac{\gamma_x}{E}-\nu \frac{\gamma_y}{E} \qquad \varepsilon_y = \frac{\gamma_y}{E}-\nu \frac{\gamma_x}{E} \qquad \varepsilon_{xy} = \frac{\gamma_{xy}}{E}*2(1+\nu) $$ $$\varepsilon_{1,2} = \frac{\varepsilon_x+\varepsilon_y}{2} \pm \frac{\sqrt{(\varepsilon_x-\varepsilon_y)^2+\varepsilon_{xy}}}{2}$$

Thin Shell

$$ \gamma_x=S_{x_G} \pm \frac{6*M_{x_G}}{t^2} \qquad \gamma_y=S_{y_G} \pm \frac{6*M_{y_G}}{t^2} \qquad \gamma_{xy}=S_{xy_G} \pm \frac{6*M_{xy_G}}{t^2}$$

Thick Shell

$$ \gamma_x=\frac{N_{x_G}}{t} \pm \frac{6*M_{x_G}}{t^2} \qquad \gamma_y=\frac{N_{y_G}}{t} \pm \frac{6*M_{y_G}}{t^2} \qquad \gamma_{xy}=\frac{N_{xy_G}}{t} \pm \frac{6*M_{xy_G}}{t^2}$$

com/nastranfrom.1518808215.txt.gz ยท Last modified: 2018/02/16 14:10 by phil