Variance reduction does not alter the core mechanics of the control loop. Instead, it focuses on reducing the variance in the computation of the control PSD. As a result, the resulting control spectrum adheres more rapidly to stringent alarm limits, which proves particularly advantageous for extremely brief test durations.
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MIMO SRS vibration testing is challenging to execute due to stringent hardware and software control requirements.
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Crystal Instruments Multi-Exciter Single- Axis (MESA) vibration test control allows users to closely replicate real-world applications according to the complex and multi-DOF nature of real vibrations. MESA vibration testing is most commonly used with higher forces on each axis and with long vertical dimensional testing units. Crystal Instruments provides the highest quality and technologically advanced solutions for MESA vibration testing and recently provided comprehensive MESA testing on a dual 300 KN shaker system at an industrial environmental testing lab.
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This article discusses the concept and implementation of a unique safety feature for environmental testing with a focus on Multiple Exciter Single Axis (MESA) vibration testing.
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Frequency Response Function (FRF) is widely used in structural testing. Accelerometers are typically used and the acceleration vs. excitation force is measured as FRFs.
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This paper concentrates on the MESA Sine on Random control per MIL STD 810H, method 514.8, annex D, 2.3 category 14. This category governs Sine on Random control for helicopters.
Crystal Instruments designed and released the Spider-80M Multiple-Exciter Single-Axis (MESA) vibration controller in 2018. Further details regarding the MESA testing system are available on the Sentek Dynamics website. Detailed product specifications may be requested from the Crystal Instruments team.
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Shock Response Spectrum (SRS) testing is commonly required for defense applications. The UUTs are tested under significantly high levels of shock waveforms.
The concept of SRS predictive notching was proposed a few years ago to fully test UUTs and ensure their survival experiencing real-world vibrations while protecting it from over testing.
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This paper discusses the usage and unique features of Multiple-Exciter Single-Axis (MESA) control with Crystal Instruments vibration controller.
MESA is a type of multiple exciter setup with all exciters arranged along a single axis. The goal is to combine the excitation forces and dimensional capabilities from multiple exciters to test a long and/or large Unit Under Test. MIL-STD-810G Method 527 discusses the terminology involving single and multiple exciter testing configurations.
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Aerospace hardware (i.e., space crafts) require high intensity acoustic level testing, which is usually accomplished inside a RATF (reverberant acoustic test facility). The acoustic noise level inside the RATF at NASA Plum Brook test station can reach 163 dB, which is the highest level among all RATFs around the world.
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Founded in 1996, Crystal Instruments designs and manufactures instrumentation products for machine vibration monitoring, dynamic measurement, and environmental testing. The products are developed in Silicon Valley and our modern lab in North Carolina. Crystal Instruments products are thoroughly tested on a variety of vibration shakers and environmental chambers in our lab during the design phase to meet the extreme requirements of military and aerospace applications.
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EDM Modal software provides the Playback Analysis feature which allows users to import recorded time signals and process measurement data to obtain the related spectrum signals. This feature allows users to carry out all the field measurements in one attempt before post-processing and analyzing the measured data in detail on a lab PC.
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The Minimum Energy option of MIMO Random is implemented to handle the nonlinearity of a multi-shaker table and provide fast convergent control.
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With Modal Analysis software, all DOFs on the mesh of a structure under test needs be measured. The common practice is using the Input channel setting, with one incremental value to move on to the next batch of measurement points till all DOFs are measured.
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Multiple-Input Multiple-Output (MIMO) vibration testing has increased in popularity as a result of the development of multiple shaker table systems and the availability of MIMO vibration controllers. The readiness of standards such as Mil-STD 810G Method 527 and the IEST DTE 022 Working Group Recommendation have also contributed to the huge momentum MIMO testing has gained in the past decade.
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Multiple-Input Multiple Output (MIMO) Testing has gained a huge momentum in the past decade with the development of multiple shaker table systems, the availability of MIMO vibration control systems, and the readiness of standards (e.g., MIL-STD 810G Method 527, IEST DTE 022 Working Group Recommendation).
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