Structural dynamics

The structural dynamics is concerned with the movements of structures as a result of time-dependent loads. An example of such loads is wind. The resulting movements are in particular vibrations . The structures examined can be machines, machine elements or structures. If the distortions in the elastic range are applied linearly, the mode shapes can also be determined. The most common programs for the computer-aided solution of structural dynamic problems are NASTRAN , ANSYS , Abaqus and LS-DYNA . As a rule, these programs can also be used for nonlinear problems, e.g. B. be used in the chassis or body area.

application areas

The area of application of structural dynamics is large. The structural dynamics covers the frequency range approximately between 0 and 1000 Hz. a. the following areas for structural dynamics:

Structural vibrations are often undesirable, e.g. B. the roar of body panels or the vibrations in the drive train of vehicles. Sometimes the vibrations are desired or necessary, e.g. B. with vibratory feeders or microphones . Structural dynamics provides methods with which these structures can be analyzed in theory or by experiment.

Adjacent areas that also intersect with structural dynamics include:

Machine acoustics : It differs from structural dynamics in particular in the frequency range considered. For machine acoustics, this is between 100 and 16,000 Hz.
Structural mechanics : This deals with the dimensioning of structures under static, dynamic and thermal loads.

A possible distinguishing feature between multi-body dynamics and structural dynamics is the consideration of the degrees of freedom used. There can be thousands of degrees of freedom in structural dynamics. Schiehlen and Eberhard make the following statement in their book "Technical Dynamics": " ... The main areas of application of the finite element method are in structural dynamics, while the method of multi-body systems is preferred in machine dynamics ... "

Finite elements

In the case of finite elements, the system is usually described by:

{\ displaystyle M (t) \, {\ ddot {\ vec {d}}} + C (t) \, {\ dot {\ vec {d}}} + K (t) \, {\ vec {d }} = 0}

With

${\ displaystyle {\ vec {d}}}$ : (time-dependent) nodal displacement vector
${\ displaystyle M}$ : Mass matrix
${\ displaystyle C}$ : Physical damping matrix
${\ displaystyle K}$ : Stiffness matrix

Web links

CADFEM Wiki

literature

Gasch , Knothe , Liebich: Structural Dynamics. 2nd edition, Springer Vieweg, 2012, ISBN 978-3-540-88976-2
Markert : structural dynamics. Technical University of Darmstadt, 2010

Individual evidence

↑ Structural Dynamics Volume 1: Discrete Systems . Springer Berlin Heidelberg, Berlin, Heidelberg 1987, ISBN 978-3-662-10127-8 .

↑ Daniel Pinyen Mok: Partitioned solution approaches in structural dynamics and fluid-structure interaction . 2001, ISBN 978-3-00-007974-0 . On-line
↑ Knothe, Klaus, Liebich, Robert: Structure dynamics: Discrete systems and continua . 2nd Edition. Springer, Berlin, Heidelberg 2012, ISBN 978-3-540-88977-9 .
↑ Markert: Structural Dynamics. TU Darmstadt, 2010, page 3
↑ Markert: Structural Dynamics. TU Darmstadt, 2010, page 3
↑ Schiehlen, Eberhard: Technical dynamics. 3rd edition, Vieweg + Teubner, 2012, ISBN 978-3-8348-1492-0 , page 186
↑ Jens Neumann: DISSERTATION: Application of adaptive finite element algorithms to problems of structural dynamics . Ed .: Universität Fridericiana zu Karlsruhe TH. ( d-nb.info ).

[1] Structural Dynamics Volume 1: Discrete Systems . Springer Berlin Heidelberg, Berlin, Heidelberg 1987, ISBN 978-3-662-10127-8 .