MIL-STD Method 527 Multi-Exciter Compliance Testing
Multi-exciter testing demonstrates when material can structurally and functionally withstand a specific dynamic environment. As a MIL-STD-810 certified lab, we realize the importance of MIL-STD-810 multi-exciter testing (MET). Meeting the MIL-810 testing standard requirements can be difficult. We understand the challenges and guide companies through the process.
Keystone Compliance provides comprehensive reports shortly after completion of the MIL-810 standard testing. We have a reputation of helping customers achieve their MIL-STD-810 product certifications. When products do not meet the requirements, we assist with finding solutions. Lastly, Keystone takes pride in partnering with customers to achieve MIL-STD-810 product compliance.
The Importance of MIL-STD Multi-Exciter Compliance Testing
The MIL-STD 810 compliance test methodology is performed to provide a degree of confidence if multiple test items are considered. Another purpose of this test is to demonstrate if materials can structurally and functionally withstand a specified dynamic environment.
This military test method is used for all types of material except as noted in the following paragraph below. For combined environment tests, conduct the 810-test in accordance with the test documentation.
How Multi-Exciter Testing Method 527 Affects Products
A multi-exciter test will distribute excitation energy to the test item. The effects of in-service boundary conditions must be reduced. The following list is a partial list of effects that may be better replicated in the laboratory under a MET.
- Fatigue, cracking, rupture sensitive to multi-axis excitation
- Deformation of material structure, e.g., protruding parts
- Loosening of seals and connections
- Displacement of components
- Chafing of surfaces with single-axis design
- Contact, short-circuiting or degradation of electrical components
- Misalignment of material components
Information on the Military Standard 810 Test Method
Generally, a MET-specified environment may occur at any time during a materials life cycle. The environment may be scattered among specially designed multiple axis SET environments such as shock. Perform tests representing critical end-of-mission environments last. For most MIL-STD 810 tests, this can be varied to accommodate test facility schedules or other practical reasons.
Two basic MIL-810 test procedures are defined under MET. Based on the data requirements, this multi-exciter testing compliance method may be applicable for the test item.
Procedure I – Time Domain Reference Criteria – This procedure is an extension to the SESA Time Waveform Replication technique addressed in Method 525. As with the case for SESA, the time histories measured or synthesized for a MEMA TWR test are not limited to stationary Gaussian structures.
Procedure II – Frequency Domain Reference Criteria – This MET procedure is an extension of Method 514, vibration testing. As with the case for SESA, the time histories synthesized for a MEMA random test will be stationary and Gaussian in structure.
Both MIL-STD-810 standard procedures will require in-service measured response data. Procedure I will require multiple time traces. Procedure II requires the measured data to be processed into auto and cross spectral density estimates.
One major consideration, while selecting Procedure I, is the ability to address scenarios in which the reference signal statistics are not stationary and gaussian. Procedure II should be considered if the reference data is stationary. Also, if the ensemble of signals representing the service life and/or time compression is to be employed.
Limitations of MIL-810 Multi-Exciter Testing Test
This method addresses very general testing configurations for applying excitation in multiple axes to material. The overall goal of a MET is to achieve a distribution of material excitation energy that appears during true environmental conditions.
Minimizing the difference between in-service and laboratory boundary conditions can also be achieved while setting this goal. The engineering analysis and judgement will be required to ensure the test fidelity is sufficient to meet all test objectives.
The following limitations also apply to this MIL STD testing method:
- It does not address aspects of vendor-supplied software control strategy for a MET.
- It does not address advantages or losses of Procedure I and Procedure II MET as defined in the paragraph above. The state of the art in a MET is not such that a comprehensive comparison can be made at this time.
- It does not address technical issues related to axes of excitation and material mass and product moments of inertia.
- It does not discuss the potential for efficiencies and efficacies of a MET over SET. Leaving this as a part of the specification of MET peculiar to the in-service measured environment.
- It does not discuss optimum in-service measurement configuration factors consistent with a MET.
- It assumes that excitation is provided mechanically through electro-dynamic or servo-hydraulic exciters. It does not consider combined acoustic or pneumatic induced modes of excitation.
Expert MIL-STD Multi-Exciter Method 527 Testing Services
Keystone’s expert MIL-810 environmental test engineers strive to give our customers more time and energy on product development instead of testing. Keystone has a full lab of test equipment which permits us to provide short lead times on scheduling. In addition to MIL-STD-810 multi-exciter testing, Keystone has a full scope of expertise including pyroshock, immersion, solar radiation, and fungus.
Contact us to receive more information on military 810 environmental testing. Request a quote and learn why manufacturers rely on Keystone Compliance to meet their shock testing, multi-exciter lab testing, and MIL-STD 810 lab compliance testing needs.