State of Stress & Stress Tensor \( ^i \) 
Stress Tensor

Stress components in a 3D element

 \(\sigma_x=\)
 
 \(\sigma_y=\)
 
 \(\sigma_z=\)
\(\tau_{xy}=\)
 
\(\tau_{xz}=\)
 
\(\tau_{yz}=\)
\(\sigma=\) \( \begin{bmatrix} \sigma_{x} & \tau_{x y} & \tau_{x z} \\\ \tau_{yx} & \sigma_{y} & \tau_{yz} \\\ \tau_{zx} & \tau_{zy} & \sigma_{z} \end{bmatrix}=\)  
 
 
Sx Txy Txz
Tyx Sy Tyz
Tzx Tzy Sz
 
 
Transformation of Stress \( ^i \) 
Stress Transformation

Transform stresses according to specified orientation angles in 3D space.

Direction Cosine Angles (α, β, θ) with Respect to x, y, and z Axes
\(\alpha=\)
 
 \(\beta=\)
 
 \(\theta=\)
 \( cos^2(\alpha) + cos^2(\beta) + cos^2(\theta)=\)
 
\( \begin{bmatrix} \alpha \\\ \beta \\\ \theta \end{bmatrix}=\) 
 
 
A
B
T
 
 
 
\(n=\) \( \begin{bmatrix} cos\alpha \\\ cos\beta \\\ cos\theta \end{bmatrix}=\) 
 
 
A
B
T
 
 
Waiting for inputs... \( cos^2(\alpha) + cos^2(\beta) + cos^2(\theta)=1 \) sould be satisfied for stresses at the oriented direction
\( cos^2(\alpha) + cos^2(\beta) + cos^2(\theta)=1 \) sould be satisfied for stresses at the oriented direction
Normal and Shear Stress in the Oriented Direction
\(\sigma\prime=\)
 
\(\tau\prime=\)
Principal Stresses
Characteristic Equation
$$ \det(\mathbf{\sigma} - \lambda I)=\lambda^3 - I_1 \lambda^2 + I_2 \lambda - I_3 = 0 $$
Invariants
\(I_{1}=\)
 
\(I_{2}=\)
 
\(I_{3}=\)
Principal Normal Stresses & Principal Directions
\(\sigma_{1}=\)
\(n_1=\begin{bmatrix} cos\alpha_1 \\\ cos\beta_1 \\\ cos\theta_1 \end{bmatrix}=\)
 
 
A1
B1
T1
 
 
 
   \( \begin{bmatrix} \alpha_1 \\\ \beta_1 \\\ \theta_1 \end{bmatrix}=\)
 
 
A1
B1
T1
 
 
\(\sigma_{2}=\)
\(n_2=\begin{bmatrix} cos\alpha_2 \\\ cos\beta_2 \\\ cos\theta_2 \end{bmatrix}=\)
 
 
A1
B1
T1
 
 
 
   \( \begin{bmatrix} \alpha_2 \\\ \beta_2 \\\ \theta_2 \end{bmatrix}=\)
 
 
A1
B1
T1
 
 
\(\sigma_{3}=\)
\(n_3=\begin{bmatrix} cos\alpha_3 \\\ cos\beta_3 \\\ cos\theta_3 \end{bmatrix}=\)
 
 
A1
B1
T1
 
 
 
   \( \begin{bmatrix} \alpha_3 \\\ \beta_3 \\\ \theta_3 \end{bmatrix}=\)
 
 
A1
B1
T1
 
 
Max Shear Stress
\(\tau_{max}=\)
Mohr's Circle