$\varepsilon_{x} = \frac{1}{E}\left\lbrack \sigma_{x} - \nu(\sigma_{y} + \sigma_{z}) \right\rbrack$, G=$\frac{E}{2(1 + \nu)}$, Jednoos st napr (ścisk/rozc): $\varepsilon_{z} = \frac{1}{E}\sigma_{z}$, ε_y=ε_y=$- \frac{\nu}{E}\sigma_{z}$=− νε_z; PSN: σ_z=τ_xz = τ_yz=0, $\mathbf{\varepsilon}_{\mathbf{z}} = - \frac{\nu}{E}\left\lbrack \sigma_{y} + \sigma_{z} \right\rbrack$,
$\mathbf{\sigma}_{\mathbf{x}} = \frac{E}{1 - \nu^{2}}$(ε_x+ε_y); tg2ρ=$\frac{2\tau_{xy}}{\sigma_{x} - \sigma_{y}}$, σ_x + σ_y=σ₁ + σ₂ Roz/Śc: ε=$\frac{N}{\text{EA}}$, ε=$\frac{\Delta l}{l}$ Δl=$\frac{Nl}{\text{EA}}$, Zgin: σ_z=$\frac{M_{x}}{W_{x}}$, τ_zy=$\frac{{T_{y}S}_{x}}{I_{x}b}$, Zg ukoś: σ=$\frac{M_{x}}{W_{x}} - \frac{M_{y}}{W_{y}}$, σ_ext=$\frac{{|M}_{x}|}{W_{x}} + \frac{{|M}_{y}|}{W_{y}}$ Roz mim:
σ =$\frac{N}{A} + \frac{M_{x}}{W_{x}} - \frac{M_{y}}{W_{y}}$ Stat: P_kr=$\frac{\pi^{2}\text{EI}}{l_{w}^{2}}$, λ=$\frac{l_{w}}{i}$> λ_gr=$\pi\sqrt{\frac{E}{\sigma_{\text{pr}}}}$, i=$\sqrt{\frac{I_{\min}}{A}}$, σ=$\frac{P_{\text{kr}}}{A}$<σ_pr, Nośność graniczna: a)zak spręż: $\frac{{|M}_{\text{dop}}|}{W_{x}}$=σ_pl, b)uplastycz przekroju: M_gr=W_plσ_pl=2S₁σ_pl, M_gr=σ_pl, tS₁ + σ_pl, cS₂, σ_pl, tA₁ = σ_pl, cA₂równ osi