mechanical-engineering

## What I do - Design mechanical components and assemblies - Analyze stress, strain, and deformation - Select materials for mechanical applications - Design mechanical systems (hydraulic, pneumatic, thermal) - Create detailed drawings and specifications ## When to use me - When designing mechanical components or machines - When analyzing structural integrity - When selecting materials for applications - When designing hydraulic or pneumatic systems - When creating manufacturing drawings ## Key Concepts ### Statics and Strength of Materials ```python import numpy as np # Basic stress calculations def normal_stress(P, A): """σ = P/A""" return P / A def shear_stress(V, A): """τ = V/A""" return V / A def bending_stress(M, y, I): """σ = My/I""" return M * y / I def torsion_stress(T, r, J): """τ = Tr/J""" return T * r / J # Strain calculations def axial_strain(delta_L, L): """ε = ΔL/L""" return delta_L / L def poisson_ratio(epsilon_lat, epsilon_ax): """ν = -ε_lat/ε_ax""" return -epsilon_lat / epsilon_ax # Hooke's Law def youngs_modulus(sigma, epsilon): """E = σ/ε""" return sigma / epsilon ``` ### Material Selection ```python # Material properties database MATERIALS = { "steel_1040": { "E": 200, # GPa "nu": 0.29, "yield": 290, # MPa "ultimate": 520, "density": 7850 # kg/m³ }, "aluminum_6061": { "E": 69, "nu": 0.33, "yield": 275, "ultimate": 310, "density": 2700 }, "titanium": { "E": 110, "nu": 0.34, "yield": 880, "ultimate": 950, "density": 4500 } } def select_material(stress, safety_factor, requirements): """Material selection based on requirements""" working_stress = stress * safety_factor candidates = [] for name, props in MATERIALS.items(): if props["yield"] >= working_stress: if props["density"] <= requirements.get("max_density", 10000): candidates.append(name) return candidates ``` ### Machine Design ```python # Shaft design class ShaftDesign: @staticmethod def torsion_stress(T, d): """τ = 16T/(πd³)""" return 16 * T / (np.pi * d**3) @staticmethod def combined_stress(M, T, d, E, nu): """Using distortion energy theory""" bending = 32 * M / (np.pi * d**3) torsion = 16 * T / (np.pi * d**3) von_mises = np.sqrt(bending**2 + 3 * torsion**2) return von_mises @staticmethod def deflection(M, L, E, I): """Simply supported beam with point load at center""" return M * L**2 / (48 * E * I) ``` ### Power Transmission ```python # Gear design class GearDesign: @staticmethod def pitch_diameter(n, p): """D = nP or D = N/p""" return n / p @staticmethod def gear_ratio(N_large, N_small): """GR = N_large/N_small""" return N_large / N_small @staticmethod def tangential_velocity(d, n): """V = πdn/12 (ft/min)""" return np.pi * d * n / 12 @staticmethod def gear_tooth_strength(J, V, F, K): """Lewis equation modified""" return F * Y / (P * K * J) ``` ### Fluid Power ```python # Hydraulic system class HydraulicSystem: @staticmethod def cylinder_force(pressure, bore_area): """F = pA""" return pressure * bore_area @staticmethod def cylinder_speed(flow, area): """v = Q/A""" return flow / area @staticmethod def pump_power(pressure, flow, efficiency): """HP = pQ/1714 × efficiency""" return pressure * flow / 1714 / efficiency ``` ### Thermal Systems ```python # Heat transfer class HeatTransfer: @staticmethod def conduction(Q, k, A, dT, L): """Conduction: Q = kA(dT/L)""" return k * A * dT / L @staticmethod def convection(Q, h, A, dT): """Convection: Q = hA(dT)""" return h * A * dT @staticmethod def radiation(Q, emissivity, A, T_hot, T_cold): """Radiation: Q = εσA(T_hot⁴ - T_cold⁴)""" sigma = 5.67e-8 return emissivity * sigma * A * (T_hot**4 - T_cold**4) @staticmethod def overall_heat_transfer(U, A, LMTD): """Q = U × A × LMTD""" return U * A * LMTD ``` ### Common Standards - **ASME**: Boiler and Pressure Vessel Code - **ANSI**: American National Standards - **ISO**: International Standards - **GD&T**: Geometric Dimensioning and Tolerancing - **SAE**: Automotive and aerospace standards