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Vibration and Shock Test Machines for Large Ship Systems Components
Navy SBIR 2009.2 - Topic N092-127 NAVSEA - Mr. Dean Putnam - dean.r.putnam@navy.mil Opens: May 18, 2009 - Closes: June 17, 2009 N092-127 TITLE: Vibration and Shock Test Machines for Large Ship Systems Components TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes ACQUISITION PROGRAM: DDG 1000 Program, PMS 500, ACAT 1 OBJECTIVE: Develop of an innovative approach for conducting shock and vibration testing for large, complex component geometries weighing up to 100,000 lbs. DESCRIPTION: Components/Equipments/Systems in excess of 10,000 lbs. that are intended for use in a shipboard environment cannot be equitably tested for both shock and vibration. The available technology varies based on the size and weight of the item and associated fixtures being subjected to testing. Vibration testing is conducted on items weighing less than 10,000 pounds and fall within testing size limits. Items that are not vibration tested are either installed on ships without verification or are verified by analysis methods that have not themselves been verified and validated (benchmarked) and are therefore not accredited for use. Shock testing is conducted on items and associated fixtures weighing up to 400,000 pounds and is also size constrained based on the test device used. In addition, shock testing and vibration testing are often performed at one or more test facilities on separate test machines resulting in the need to build-in long testing windows into the production/delivery schedules as well as allot for increased costs to transport the test item to and from test location to test location. Limits associated with vibration testing are directly attributed to the design capabilities of the test machines themselves. There are three basic types of vibration test machines (or shakers): 1) mechanical, 2) servo-hydraulic, and 3) electro-dynamic. Mechanical shakers provide sinusoidal, fixed-displacement, single-frequency-at-a-time vibration and cannot provide variable strokes needed for realistic simulation or provide the higher frequency capability needed for most testing (typically limited to frequency range of 10 to 60 Hz). Servo-hydraulic shakers are limited by their ability to provide required hydraulic pressures at controlled flow-rates while maintaining linear, load continuity. Electro-dynamic shakers are limited in stroke (less than 3 inches), are severely limited in generating force at low frequency (10 Hertz or less) and are velocity limited at low frequencies to about 70 inches per second. In the case of sinusoidal vibration testing, low-amplitude, long-duration frequency pulses are utilized. The flow-rate has to be held at a constant pressure over a long period of time (hours). In the case of shock testing, high-amplitude, short-duration pulses are utilized. Flow-rate is controlled on the micro-second level. With both shock and vibration testing, maintaining linear load continuity is considered key. Both testing configurations require large amounts of highly pressurized fluid which is distributed based on the size and shape of the item being tested. If the test apparatus flow-rate becomes non-linear and uncontrollable, the item, test apparatus (and likely the personnel conducting the test) are put at risk. The heavier the item being tested, the more pressure is needed to deliver the fluid which in turn impacts the fluid’s flow characteristics and behavior. This topic seeks innovative approaches to provide an apparatus that combines shock and vibration testing capabilities into a single test system for items up to 100,000 pounds. This capability will allow the Navy to: 1) improve survivability performance of naval shipboard equipment and systems, 2) mitigate shock and vibration risks carried by ship programs and 3) be more cost effective from a testing perspective as only a single test facility will be needed vice two or more. New R&D based technological approaches and/or methodologies are required. A key challenge is to develop one system for both shock and vibration testing for large items with complex geometries while providing controlled load continuity over the appropriate frequency ranges for the necessary periods of time. The proposer needs to be mindful that each item to be subjected to testing will have it’s natural frequencies. Concepts proposed need to be configurable to item-specific shipboard installations geometries to account for a range of equipment sizes (up to 14 feet in width, 45 feet in height and 26 feet in length), weights (up to 100,000 lbs) and various center of gravity locations. The test control inputs (accelerations, velocities and displacements) are to be easily programmed, modified and recorded as required for ship-specific loading conditions per Ref’s 2 and 3. PHASE I: Demonstrate the feasibility of a shock and vibration test machine that address the criteria referenced above. Develop an initial conceptual design and establish performance goals and metrics to analyze the feasibility of the proposed solution. Perform bench top experimentation where applicable to demonstrate concepts and show that the proposed concept is scalable to test item weights up to 100,000 pounds. PHASE II: Finalize the design concept from Phase I and fabricate a scaled prototype (for items weighing up to 5000 pounds). In a laboratory environment, demonstrate that the prototype meets the performance goals established in Phase I. Develop Phase III plan for scaled prototype development and applicable testing procedures to measure the effectiveness of the concepts ability to test lightweight, mediumweight and heavyweight equipment in accordance with Ref’s 2 and 3. PHASE III: Working with government and industry, construct a full-scale prototype and conduct extended testing to validate systems ability to provide both shock and vibration testing for lightweight, medium weight, and heavyweight items for installation onboard naval ships. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This system could be used by any private sector or commercial activity that has a need to provide both shock and vibration testing for components in excess of 10,000 lbs. (i.e., consumer electronics, medical devices, heavy road vehicles, aerospace assemblies, earthquake testing etc.). Many of the prime defense contractors have a need for being able to apply this technology to their applicable defense technologies. REFERENCES: 2. MIL-S-901D, "SHOCK TESTS, H.I. (HIGH-IMPACT) SHIPBOARD MACHINERY, EQUIPMENT, AND SYSTEMS, REQUIREMENTS FOR. 3. MIL-STD-167-1A, "Mechanical Vibrations of Shipboard Equipment (Type I – Environmental and Type II – Internally Excited)" 4. TEAM, www.teamcorporation.co.uk 5. MTS, www.mts.com KEYWORDS: Shock; Vibration; Testing; Instrumentation; Data Acquisition; Analysis
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