asimov studies

Absorption coefficient The absorption coefficient determines how far into the material light penetrates before being absorbed. the absorption depends on the material and the wavelenght of the light absorption coefficient = extinction coefficient * 4 * pi/wavelength absorption coefficient = attenuation coefficient - scattering coefficient Biot Number Biot Number represents the tendency for heat incident upon the material to spread throughout the material.  Beam Element in a beam element, deflection only occurs in the direction perpendicular to its axis. Bore Bore is the inner diameter of the cylinder of the engine. Boundary Layer the Boundary layer is a viscous layer where the viscous effects are considered, and the velocity gradient is high. Buckling Buckling is a failure mode characterized by a sudden failure of a structure member subjected to high compressive stresses. Buoyancy buoyancy (thermal effect) is caused by a temperature gradient. the more the temperature gradient the more is the buoyancy effect. Camshaft the Camshaft is responsible of opening and closing the valves of the engine. Casting Casting is a manufacturing process by which a liquid material is poured into a mold which contains the shape of the body. Coefficient of Thermal Expansion Coefficient of thermal Expansion is a dimensiosless number that measures how the material changes with temperature effects.   less coefficient of thermal expansion will result in more reliable product at high temperatures. Composites Composites are structural material systems composed of a one or more materials. Compresser a Compresser is a centrifugal pump that have blades. air entering perpendicular to the blades spins with the blades and is exhausted at a higher pressure. Compressible Flow  in a Compressible Flow, the density changes with time, changes in pressure or temperature will result in a change in density. Drho/Dt is not equal to 0. Compression Ratio compression ratio represents the ratio of the area in the Combustion Chamber of a Car when the piston is at the bottom (full) to when the piston at the top (empty). a higher compression Ratios is better for mixing, for mixing gasoline with air in a smaller volume will produce better efficiency. Convection heat transfer coefficient Convection Heat Transfer Coefficient h (w/m2 k) the thermal properties of the liquid transporting the heat. Crankshaft the crankshaft is the part in the engine that turns the pistons up and down through the connecting rod Damping damping is defined as dissipating energy from a vibrating structure. (dissipating energy, meaning transforming energy to heat). damping controls how he system responds to resonance; With high damping, the more slowly the amplitude builds up to its maximum as the driving frequency is increased. for low damping values, there is a sudden increase in amplitude next to resonance, and a sudden drop afterwards. Discrete Fourier Transforms Discrete Fourier Transforms are used to convert a time domain graph to a frequency domain one. Emissivity Emissivity is between 0 and 1 and measures how efficiently a material emits energy. For black body the emissivity is 1  Engine Displacement the Engine Displacement is the overall volume displaced in all the combustion chambers of the engine, it is mainly in cc. Energy (internal) Internal energy is the sum of kinetic and potential energy of a system. Energy (Kinetic) Kinetic Energy is the energy of a mass due to its movements. Energy (Potential) Potential Energy is the stored enegy (Example: Elastic band stretched, has potential energy when is released Fluid Dynamics  Fluid Dynamics is the science that deals with the solution of: velocity, pressure, temperature, density of a fluid flow. Fracture Fracture Toughness is the measure of how much stress is needed to continue propagating an established crack Frequency The Frequency is defined as the repetition of a specified occurance per unit time, for waves, the frequency is the velocity/wavelenght.   Frequency Domain in a Frequency Domain, the signal lies in a specified frequency. Froude Number Froude Number is a dimensionless number that measures the ratio of the inertial forces to gravitational one. the higher the Froude number the less the fluid resist flow. Geometric non linearity Non Linearity is defined by large strain, stress, and deformation. Grashof Number Grashof number is used in natural convection to predict the flow as (laminar, transient or turbulent). it is defined as the ratio of buoyant forces (caused by temperature gradient) to viscous ones. the higher the Grashof number the more the fluid is able to migrate, and the flow is tending to turbulence if Gr >> 1. Hardness the Hardness of a material is defined as its resistance to cutting, abrasion, and its resistance to deformation. Shore is a measure of hardness, the higher the shore the harder is the material. Harmonic the Harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundemental frequency. The fundemental frequency is the lowest frequency in a harmonic series. In mechanical analysis, you ll have a beam and a mass attached to it. Heat Flux Heat Flux is the heat divided by the surface  (Q/A). for conduction to be q = K dT Heat transfer Coefficient heat transfer coefficient h (W/m^2 K) = q(W/m^2)/dT(K) Incompressible Flow  in an Incompressible Flow, the density does not change with time, thus the density is constant, Drho/Dt equal 0. Inertia moment of inertia is required for analysing problems involving the rotation of rigid bodies. the formulation is I = m K2 m = mass of the rigid body; K = radius of gyration about the point of rotation. Inviscid Flow Inviscid Flow is characterized by a constant visocisity, and is not affected by fluid friction (viscosity is negligeable). Kinematic Viscosity Kinematic viscosity is the ratio of the viscous force to inertial force. Laminar Flow a Laminar Flow is characterized as a flow with prallel layers of stream flows with a velocity and pressure independant of time. Modal (structural analysis) Any physical system can vibrate. The frequencies at which vibration naturally occurs, and the modal shapes which the vibrating system assumed are properties of the system, and can be determined analytically using Modal Analysis. Modulus of Elasticity whithin the limit of proportionality of a material, the strain produced is directly propotional to the stress producing it, stress = E x strain; with E the modulus of elasticity (Pa). The Higher the modulus of Elasticity, the more brittle is the material, and the less deflection the material have under a defined stress. Modulus of Rigidity Rigidity is defined as shear stress / shear strain; Moment of Inertia Moment of Inertia is a property of a rigid body, representing the ability of a mass to resist bending. it relates the torque (rotational accelertion) to the rotational acceleration and it is relative to an axis. Newtonian Fluids  Newtonian Fluids are fluids whose stresses and strains are linearily propotional (E= stress/strain) with the viscosity as the constant of proportionality  Non Condensing air air will not condense to liquid phase in any circumstances (cooled or compressed to its saturation limit). Non Linear Modeling Non Linear Modeling is used when the material is under a stress that is far beyond the material yield point. Non Linearity Non Linearity is characterized by large deformation, plasticity, stress stiffening, contact gap elements. Nusselt Number Nusselt Number is an indicator of the relationship between the fuild capacity to convect heat versus conducting it. for a fluid to remove heat from a surface, heat must first be conducted into the fluid to be removed. convection heat transfer depends on how fast the fluid flows and on how well it conducts near the surface, the ratio between the fluid's ability to conduct heat and then move it away is called the nusselt number. the higher the nusselt number, the better is the fluid in removing heat from a surface. Octave an Octave is the interval between two frequencies with an interval of 2 to 1 Peclet Number the Peclet Number is a dimensionless number representing the ratio of the thermal energy convected to the fluid to the fluid to the thermal energy conducted within the fluid (diffusion). the higher the Peclet number the convection is more crticial than diffusion. Period a Period is the time required for a complete oscillation. Phase Change Phase Change is the transformation of a thermodynamic system from one phase to another. Photon light consists of little, massless, chargeless particles called photons that travel at speed of light. photons carry an energy propotional to the frequency, the higher the frequency the higher their energy. Piezoelectric Piezoelectric is the ability of some materials (notably crystals  to generate an electric potential). Poisson Ratio Poisson Ratio is the ratio of shear strain to tensile strain (= -shear strain/tensile strain). Polymer polymers are formed by chains of molecules, due to their long chains they are maleable, bendable and consititues the majority of plastics and synthetics. Prandtl Number Prandtl number = viscous diffusion rate/thermal diffusion rate = cp*µ/k Prandtl Number shows the capacity of a fluid to store heat versus its conductive capacity. Prandtl number depends only on the fluid properties. if the fluid is more conductive than convective than Pr is small, and the thermal boundary layer is bigger than the velocity boundary layer. Pressure Drop Pressure drop is a term used to indicate the pressure difference between the inlet of the flow or the control volume and the defined poistion downstream. Radiation all surfaces of a specified temperature emits energy in terms of electromagnetic waves (photons). These waves are radiation waves. Rayleigh Number Rayleigh Number is a dimensionless number used in heat transfer to characterise the heat as predominently conducted (Ra << Critical value) whereas convective (Ra >> Critical Value). Rayleigh Number is a dimensionless number used in aerodynamics to characterise the flow as laminar (Ra < 10^9) whereas turbulent (Ra > 10^9). Rayleigh is defined as: buoyant forces/viscous forces, it is used in natural convection to determine if there is a buyancy effect on the flow, or if the flow is mainly conductive. Resonance Frequency a Resonance Frequency is defined as the frequency for which the response is a maximum (displacement, velocity). Reynolds number Reynolds number is a nondimensional number used as a term to differentiate between different kinds of flows (laminar, transient, turbulent). it gives a measure of the ratio of inertial forces to viscous forces. The higher the Reynold number the more the fluid is able to migrate for a flat plate: Turbulent flow is characterized by a flow with Re > 500000  Reynolds Stresses Reynolds stresses are additional terms arising from turbulent effects in Navier stokes equations. Rigide Body a rigid body is said to be a body that does not change its shape or size during motion. Rigidity  Rigidity is defined as the resistance of material to deformation and is equal to (E.I = modulus of elasticity * Moment of Inertia). Shape Optimization Shape optimization optimizes the shape under certain constraint Shear Modulus Shear Modulus is the ratio of shear stress over shear strain (shear stress/shear strain). Shear Strenght Shear Strenght is the maximum shear stress that a material can withhold without being affected by the shear stress.  Sheer Stress The Sheer Stress is the sheer force that embodies the viscous resistance to the shearing deformation of the fluid flow. Sheet Metal Sheet Metal is considered as a sheet stock with 0.25 inch or less of thickness. Specific Heat Specific Heat measures the heat energy required to raise the temperature of a specified substance by a temperature interval. The Specific heat of water is higher than metal, the less the specific heat the more conductive is the material. Spectrum (structural analysis) transform the DFT (discrete fourier transform) into a power spectrum, it is needed to view the response regarding time, any time domain can be switched to a frequency domain by viewing the sine waves (frequency, amplitudes and phases). Static (structural analysis) Static is the study that determines the displacements, stresses, strains, and forces in structures or components caused by loads that do not induce inertia and damping effects  Steady Flow (fluid dynamics) a Steady Flow is a flow independent of time. Steady State Heat Transfer  Steady State analysis of temperature, heat flow and heat flux in steady state conditions.(no change of variables with respect to time) Stiffness Tensile Stiffness is the product of Young's Modulus and the area Bending Stiffness is the product of Young's modulus and the second moment of inertia stiffness can be defined as Force / deflection (or elongation in the direction of the force) Stroke a Stroke is the full lenght of travel of a piston in an engine. Strouhal Number Strouhal number is a dimensionless number representing the oscillating frequency of a flow. the higher the Strouhal Number the more oscillation is in the flow, leading to turbulence. Subsonic - Transonic - Supersonic the flow is considered subsonic if MAch number is less than 1, transient if equal 1, and supersonic if more than 1 (shokwaves available at the transient to supersonic levels). Tensile Strength Tensile strenght is the maxiumum Tensile force that a material to tolerate force without breaking. Thermal Conductivity Thermal Conductivity, k (w/m2 k), is the transport property of the material conducting heat Thermal Diffusivity Thermal diffusivity is the ratio of thermal conductivity to volumetric heat capacity. A material with high thermal diffusivity adjust to its thermal surroundings faster than others that have a lower thermal diffusivity. Thermal Expansion Thermal Expansion represent the phenomena where all materials will undergo changes in physical dimensions in response to change in temperature. Transient (structural analysis) Transient dynamic analysis is a technique used to determine the dynamic response of a structure under a time-varying load. If inertia effects are negligible for the loading conditions, a static analysis may be used instead. Transient Heat Transfer if the temperature of the rod change over time, that means it is in a transient state or undergoing Transient heat transfer. Transmissibility Transmissibility (vibration), is the ratio of the output amplitude to the input amplitude on a system. in other words it is the ratio of vibration transmitted after isolation to the disturbing initial vibration. T = 1/[(F(Forced)/F(Natural))^2 - 1)] (not considering damping) The highest transmissibility is recorded when the forcing frequency is equal to the natural frequency. transmissibility is a factor of forcing frequency, resonant frequency, damping and critical damping. Toughness Toughness is a measure of the ability of a material to absorb energy before fracture. Turbocharger a turbocharger add power to the engine by adding more pressurized exhaust air to the intake of the engine. it is usually placed at the exhaust so that the exhaust power (air flow) spins its turbine. this turbine turns a compresser that compresses intake air into the engine. Turbulent Flow Turbulent Flow depends on Reynolds number valuation, built on scales available, where the largest scales are called eddies. Ultimate Strenght the Ultimate Strength of a material is the maximum stress that the material will withstand without breaking. Viscosity Viscosity specifies the resistance of the fluid to flow.  Viscous Flow Viscous flow is characterized by dynamic and kinematic visocsity with a variant viscosity, it is affected by fluid friction Von Misses Stress the Von Misses Stress is a scalar quantity that represents the stresses in all directions. Yield Strenght Yield Strenght is the maximum force whereas below it the material can tolerate Tensile or compressive forces without permanent deformation Young Modulus the Young's Modulus of a material is a measure of how much a material will resist deformation. the larger the youngs modulus the Stiffer is the material, meaning it will need more force to deform it.