Dynamics and Vibrations

Structures or designs which exhibit some form of oscillatory motion or are subject to external forces or constraints that harmonically vary with time fall within the category of mechanical vibrations. SECG can perform a wide array of dynamic and vibrational simulations to predict your specific design’s structural response and determine key performance characteristics such as stress, displacement, and acceleration.

Coupling SECG’s dynamics and vibration analysis capabilities with SECG’s extensive experience in both engineering and design can significantly reduce product development cycles by evaluating product designs upfront in a virtual environment to reduce time and prototyping costs.

Modal and Prestressed Modal Analysis

A modal analysis provides insight into the vibrational response of a structural design by determining the fundamental vibrational frequencies and associated mode shapes. Modal analysis simulations can provide quick results to determine if your component or assembly has fundamental frequencies within the expected operating range of the design.

If a particular design has modal frequencies within the range of excitation frequencies that occur during normal operation of the design, resonance can occur.

Furthermore, if a particular design is pre-loaded or stressed prior to being subject to vibrations, then a pre-stressed modal simulation can be used to include any stress stiffening effects that arise as a result of preloading. To determine peak displacements, accelerations, and stresses, a forced vibration simulation will have to be used that includes material damping.

Forced Vibration Simulation

Forced vibration simulations can provide a great deal of insight into how a particular design responds to a range of excitation frequencies with specified amplitudes. Forced vibration simulations apply a single sinusoidal excitation force at a constant or varying amplitude over a specified range of frequencies. This class of simulations also has the ability to emulate physical shaker table testing within a virtual environment by not only providing an excitation source, but also by allowing for results extractions at specified spatial locations similar to physical test instrumentation.

Integration of forced vibration simulation within the early stages of product design can dramatically reduce the number of physical iterations and time associated with physical testing by simulating within a virtual environment.

Random Vibrations

Random vibrations are typically characterized as vibrations or oscillatory motion that is non-periodic. Unlike forced vibration simulations that are periodic in nature, random vibrations are comprised of a multitude of frequencies that is represented using a power spectral density (PSD) function or curve. An automobile traveling down a rough road would be an example of random vibrations.

The real power of random vibration simulations becomes evident if the forced vibrational loading can be described statistically by a random process, because a knowledge of the past history of random motion is adequate to predict the probability of occurrence of various acceleration and displacement magnitudes in the future.

Transient Dynamic Analysis

A transient dynamic analysis serves to simulate the structural response of a design based on dynamic loading that cannot be described as periodic or dynamically random in nature. Such examples of a transient dynamic analysis would be a shock loading or impact loading where a design or structure is subject to a short duration force of varying amplitude and the response is simulated over time. Transient dynamic simulations can be computationally expensive, however this type of simulation can provide access to structural response results that would be extremely difficult to obtain during typical physical testing.

Kinematic Mechanisms / Multi-Body Dynamics

Mechanisms and machinery involving multiple components can be complex, and determination of displacements and forces can be difficult to obtain. SECG’s simulation capabilities allow for simulation of large, multi-degree-of-freedom assemblies. In addition, external forces that are time varying or functions of motion can be included in the simulation to more accurately model the true dynamic environment of your design.

SECG can create animations that not only depict the motion of your design, but will trace specific performance parameters in chart/graph format within the motion animation for easy correction between performance variables and physical motion. Lastly, SECG can take the loads derived from discrete multi-body dynamic simulations and transfer them to finite element models for simulation of component stresses at peak loading conditions.