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  2. Direct stiffness method - Wikipedia

    en.wikipedia.org/wiki/Direct_stiffness_method

    The first step when using the direct stiffness method is to identify the individual elements which make up the structure. Once the elements are identified, the structure is disconnected at the nodes, the points which connect the different elements together. Each element is then analyzed individually to develop member stiffness equations.

  3. Stiff equation - Wikipedia

    en.wikipedia.org/wiki/Stiff_equation

    In mathematics, a stiff equation is a differential equation for which certain numerical methods for solving the equation are numerically unstable, unless the step size is taken to be extremely small. It has proven difficult to formulate a precise definition of stiffness, but the main idea is that the equation includes some terms that can lead ...

  4. Active disturbance rejection control - Wikipedia

    en.wikipedia.org/wiki/Active_Disturbance...

    This disturbance rejection feature allows users to treat the considered system with a simpler model insofar as the negative effects of modeling uncertainty are compensated in real time. As a result, the operator does not need a precise analytical description of the base system; one can model the unknown parts of the dynamics as internal ...

  5. Structural dynamics - Wikipedia

    en.wikipedia.org/wiki/Structural_dynamics

    Structural dynamics is a type of structural analysis which covers the behavior of a structure subjected to dynamic (actions having high acceleration) loading. Dynamic loads include people, wind, waves, traffic, earthquakes, and blasts. Any structure can be subjected to dynamic loading.

  6. Duhamel's integral - Wikipedia

    en.wikipedia.org/wiki/Duhamel's_integral

    If a system initially rests at its equilibrium position, from where it is acted upon by a unit-impulse at the instance t=0, i.e., p(t) in the equation above is a Dirac delta function δ(t), () = | = =, then by solving the differential equation one can get a fundamental solution (known as a unit-impulse response function)

  7. Natural frequency - Wikipedia

    en.wikipedia.org/wiki/Natural_frequency

    Natural frequency, measured in terms of eigenfrequency, is the rate at which an oscillatory system tends to oscillate in the absence of disturbance. A foundational example pertains to simple harmonic oscillators, such as an idealized spring with no energy loss wherein the system exhibits constant-amplitude oscillations with a constant frequency.

  8. Four-point flexural test - Wikipedia

    en.wikipedia.org/wiki/Four-point_flexural_test

    These two loadings are lowered from above at a constant rate until sample failure. Calculation of the flexural stress σ f {\displaystyle \sigma _{f}} 4-point bend loading σ f = 3 4 F L b d 2 {\displaystyle \sigma _{f}={\frac {3}{4}}{\frac {FL}{bd^{2}}}} [ 3 ] for four-point bending test where the loading span is 1/2 of the support span ...

  9. Newmark-beta method - Wikipedia

    en.wikipedia.org/wiki/Newmark-beta_method

    The Newmark-beta method is a method of numerical integration used to solve certain differential equations.It is widely used in numerical evaluation of the dynamic response of structures and solids such as in finite element analysis to model dynamic systems.