Reference

Common Mechanical Formulas: Reliability Physics

Engineering at Edelweis is not a matter of estimation; it is a matter of calculation. We utilize a standardized library of formulas integrated into our V&V and FEA Methodology to predict performance, verify Safety Factors, and ensure parts are fit for their intended environment.

1. Structural Integrity & Stress Analysis

Calculating internal resistance to ensure materials remain within the elastic region:

Normal Stress (σ)

σ = F / A. Ensuring material does not reach yield point under axial load (F = Force, A = Area).

Factor of Safety (FS)

FS = σ_yield / σ_allowable. Mandatory margin of error (typically FS ≥ 1.5).

Hooke's Law

σ = E · ε. Predicting deformation during validation builds (E = Young's Modulus, ε = Strain).

2. Rotational Dynamics & Powertrain

•
Torque (τ): τ = F · r · sin(θ). The fundamental measurement for rotational force and actuator sizing.
•
Mechanical Power (P): P = τ · ω. Determining energy output required for motors (ω = Angular Velocity).
•
Gear Ratio (G): G = N_out / N_in = τ_out / τ_in. Synchronizing speeds across large assembly CAD.

3. Fastener & Bolted Joint Physics

Calculation	Formula	Engineering Goal
Tightening Torque	T = K · D · P	Preventing bolt fatigue and ensuring QC compliance.
Tensile Stress Area	A_t = π/4 (D - 0.938P)²	Calculating true load-bearing area of threads.
Preload Force	F_i = 0.75 · A_t · σ_p	Ensuring joint remains closed under FEA loads.

4. Thermal & Fluid Dynamics

•
Thermal Expansion (ΔL): ΔL = α · L₀ · ΔT. Predicting dimensional shifts for tolerance stack-up analysis.
•
Fluid Pressure (p): p = ρ · g · h. Fundamental for seal integrity and prototyping leak tests.
•
Reynolds Number (Re): Re = (ρ · v · D) / µ. Determining flow characteristics (Laminar vs. Turbulent) in CFD.

Technical Directives

Directive	Protocol
Calculation Logs	All manual calculations must be attached to the Audit Logs for Reviewer verification.
SI Unit Mandatory	All variables must be converted to SI units before entering formula calculations.
Conservative Bias	When in doubt, engineering decisions must favor the "Worst-Case" result of the calculation.