Rustburg, VA - Mounts

The use of Commercial-off-the-Shelf (COTS) Equipment in the shipboard environment requires the use of a shock isolation system that can meet the U.S. Navy Shipboard Specifications for Shock and Vibration. Because of the variety of applications (weight and size), and the unique isolation requirements, a family of shock isolators is necessary. The DTI Shock Mount was developed to meet requirements for installing COTS equipment in a shipboard environment. Primary considerations in the mount design were to maximize shock attenuation and minimize mount installation costs.

NTS has a family of five- and seven-inch tall mounts that can meet requirements for U.S. Navy shipboard applications. The mounts can be sized to meet the variety of weight and CG requirements that that manufacturers typically encounter. The resultant shock isolation system will meet the requirements of MIL-S-901D and MIL-S-167.

NTS Rustburg has done extensive development including heavy weight shock testing and vibration testing under the worst load conditions and is able to provide accurate analysis to assist in mount sizing or provide detailed data sheets to allow the manufacturer to conduct his/her own independent analysis to develop the required shock isolation system.

Shock Isolator Descriptions

NTS Rustburg has developed a thermoplastic alloy mount that meets the requirements of MIL-S-901D Shock and MIL-S-167 vibration. The alloy mount material is blended to optimize both vibration damping and shock attenuation characteristics. All of the mounts are manufactured using injection molding processes. Shock Load Deflection data can be found here.

Type 1 Mounts

Type 1 DTI Shock Mounts are seven-inches tall and range in wall thickness from 0.50 to 1.25 inches. These mounts are designed for equipment to be installed on lower frequency decks. The mount physical dimensions are shown in Figure 1.

Type 2 Mounts

Type 2 DTI Shock Mounts are five-inches and range in wall thickness from 0.50 to 0.88 inches. These mounts are designed for lighter and smaller equipment that is installed hull mounted. The mount physical dimensions are shown in Figure 2.

Testing Data

NTS Rustburg has conducted a series of pseudo-static and dynamic mount characterization tests and derived mount load-deflection and damping characteristics. Accurate mount characterization is critical for properly sizing mounts and predicting shock responses.

NTS Rustburg has designed and built a number of test fixtures designed specifically for mount characterization and validation testing. Specifically, fixtures were built that apply a uniaxial load to the mounts. The mounts were loaded to maximum capacity while a tandem of force and displacement gauges were utilized to generate load versus deflection data. Damping data was derived from tests conducted on a NTS Rustburg proprietary bounce test machine. Finally, data verification has been accomplished by comparing mount characteristics with data recorded during floating shock platform testing (FSP).

NTS Rustburg's mount characterization and validation program has continued as customer data requirements have increased. Please visit contact an NTS Rustburg representative for the latest mount characterization data.

Shock Test Data

NTS Rustburg has conducted heavyweight shock testing using simulated electronics cabinets. These tests were heavily instrumented to acquire data demonstrating the response of the shock isolation system under the shock loading of a MIL-S-901D shot at a 20-foot standoff, both in the fore/aft and athwartships orientations. The Shock Test Study document includes instrumentation traces showing the response of the shock isolation system. The Shock Test Study Video includes some excerpts from video that was acquired during the tests. The results demonstrate that the isolators mitigated the response to less than 20g for the system tested with no mount damage or bottoming. This was true in both the light and heavy cabinets.

Vibration Test Data

NTS Rustburg has conducted a series of vibration test in accordance with MIL-S-167-1 (Type I) using a rigid mass. When excited at discrete frequency intervals, the measured above mount acceleration levels where typically below 1.5 g's and transmissibility levels are typically less than 10 g's. At non-discrete frequency intervals, NTS experience is that g-levels are typically less than 2 Gs and transmissibility levels are less than 15 g's.

Shipboard Applications

NTS Rustburg shock mounts have been tested and qualified by a number of defense contractors and are currently in use on U.S. Navy combatant ships including the "smart ship" program, as well as LPD-17, CVN, and DDG applications.

Availability

NTS Rustburg maintains an inventory of Type 1 and Type 2 shock mounts on site and can usually fill most orders for immediate delivery. For larger orders that exceed inventory on hand, the order can usually be filled with 30-45 days lead-time.