The modal analysis allows machines and structures to be tested, optimized, and validated. Measurements made on the structure are used to construct a complete mathematical model of the vibrational properties from which the behavior of the structure can be observed. Natural resonance frequencies of the objects and damping parameters can be calculated, and mode shapes visualized on an animated geometry of the measured objects.
The resonance frequencies together with damping ratios and mode shapes are the modal parameters of the device under test. Estimation of valid modal parameters for complex structures requires modal analysis to be performed. Determined parameters provide rich insight into the structural dynamics of the tested structure - enabling a great understanding of how to do structural optimizations. Modal analysis is heavily used in civil engineering and industries such as aerospace and automotive, across a vast range of applications including:.
Dewesoft modal testing suite supports several measurement techniques or modal test configurations methods:. Modal tests can be performed via single reference shaker test and single reference roving hammer or roving accelerometers test. Multireference roving hammer and multireference shaker tests are also supported. Multi-shaker tests are normally performed with many accelerometer sensors. Dewesoft modal testing suite allows you to excite complex structures by using multiple shakers, and to measure and analyze on a virtually unlimited number of channels.
They offer some distinct advantages for the measurement and extraction of basic modal parameters especially while testing larger structures. The main advantage of using multiple shakers is that the input-force energy is distributed over more locations on the structure.
This provides a more uniform vibration response over the structure, especially in cases of large and complex structures and structures with heavy damping. Random, burst random and sine sweep excitation signals are configured directly in the Modal Test setup screen using the Function generator, and you can use MCOH multiple coherence to validate your shaker setting. Another type of roving test can also be selected, where one modal exciter hammer or shaker is used as the reference DOF, while one or a group of accelerometers will rove until all of the DOFs have been measured.
Dewesoft allows you to perform your measurement with the impact hammer single excitation point or multiple with a roving hammer and any number of response channels. This method is a powerful asset for in-depth assessment of the structural dynamics or structural vibrations.
Dewesoft can provide turn-key modal testing and modal analysis solutions with all the components above. See the details of available modal testing hardware below. Dewesoft provides a range of data acquisition systems suitable for modal testing.
Flexible input channel count configuration allows for different modal testing setups. High-end signal conditioning amplifiers offer perfect signal measurement with great dynamic range.
Our data acquisition systems are flexible by design and can be expanded to any number of input channels for no additional software cost. If high-frequency excitation content or signal-controlled testing is desired, then modal shakers are the only excitation solution. Dewesoft modal shakers are lightweight and powerful. They can operate up to 15, Hz, and provide force levels up to N with a maximum 25mm stroke.
Dewesoft modal shakers can be used for Modal testing and Structural Dynamics. The series of Dewesoft modal shakers covers a wide range of structures for dynamic characterization from electronic boards and sub-components to machinery, vehicles, and aircraft, even constructions. In addition to modal shakers and vibration sensors, Dewesoft also offers a range of roving hammers with different force ranges. Hammers up to the N range are a perfect fit for modal analysis applications using DewesoftX software.
Dewesoft modal hammers are equipped with the TEDS smart sensor interface. This allows DewesoftX software to automatically detect the hammer and set correct scaling. Whenever a high number of measured channels is used, adding and removing the excitation and response channels process is made simple with autofill setup functionality. To get you up and running quickly, DewesoftX software offers pre-defined displays for modal testing and analysis.
These predefined displays include the most often used instruments and arrangements for the acquisition and measurement process and for post-analysis of the measured data. Each predefined display will guide you step-by-step through your modal testing process. It will track your measurement progress and allow you to reject hits, reset points, and automatically detect double hits.
Animation of your structure is enabled in all three directions, and you can view it using different projections during the measurement. Of course, it is always possible to customize and change the default displays or define unlimited news ones. With the geometry editor, you can quickly draw simple 3D structures as well as import more complex models using the UNV file format. The geometry of the measured structure is defined by objects, lines, or points. The geometry editor supports cartesian and cylindrical coordinate systems, ideal for drawing circular objects.
Structures can be animated at a single frequency in all three directions with the interpolation of non-measured points. You have the ability to animate different mode shapes and compare deflections with the non-excited structure shape. This gives a thorough visual representation of the structural dynamics. The color of the points changes during the measurement for easier identification of the excitation and response points.
The structure geometry can be rendered in different projections:. The LSCF algorithm with curve-fitted results for the estimation of modal parameters is shown in a dedicated widget - the stabilization diagram. You can also display the complex mode indicator function CMIF along with any other vector channel of your choice.
AutoMAC shows the correlation between different modes. Mode indicator functions MIF , H1, and H2 estimators, power spectral density PSD are fully implemented in DewesoftX software and can be used in combination with other mathematical calculations. Import from external software in universal file format.
Dedicated interface for modal with impact hammer acquisition, shakers or under operational conditions to obtain:. ODS is a great tool to visualize dynamically the vibration deflection shape of mechanical components during their normal operation. It offers rapid visual feedback on the deformation of a structure in both time and frequency domain. The intuitive interface will guide you through the different steps of a complete modal analysis.
They were told by the motor manufacturer that the exhauster was misaligned and that the fault lay in the motor. However, the coupling broke down again within two months. It seemed nobody could permanently fix the coupling and they were stuck with a problem cycle that continued for months. The company thought that a poor alignment of the machine set was made after the coupling repair and after the next coupling repair they invited two independent companies to double check the precision of the alignment.
It was clear that the alignment was fine. However, after some time, the coupling broke down once again. In this case, if they could have seen how the machine was moving, it would have been much easier to pinpoint the exact source of their problem. Using this software enables the visualisation in animation of vibrations of a certain machine.
During the animation in ODS the vibration movement is slowed down to a very low frequency, for example 0,5 Hz, while the real frequency of the machine was 25 Hz and the amplitude of the motion is increased to a level so the human eye can see the vibration.
It is a combination of vibration measurement and software processing. The output of the method is the animation of vibration movement on one or multiple forcing frequencies. The results shown using this method are understandable to everybody who is familiar with the machine as the movement is visualized.
When you take vibration data and detect a high 1 x peak, you might define it as unbalance based on your experience or pattern recognition. But, where is it vibrating and how is it vibrating?
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