Browse Topic: Manufacturing systems
The work done in developing stretch broken carbon fiber technology is described. The objectives of the program include the scale up of the process to demonstrate production feasibility, as well as reducing the maximum filament stretch break length to ~50mm/2” or below, less than half of what was achieved on previous programs. The shorter break length is considered to be critical in order to achieve formability into complex geometries. The new stretch break line at Montana State University, BC3, has been commissioned to achieve the required material characteristics and throughput. To date, 6 tows have been successfully stretch broken simultaneously, representing a significant improvement compared with what was achieved on previous programs. Possible geometries and forming evaluation methods are described. Mechanical testing is to be conducted, including both equivalency testing of continuous vs stretch broken carbon fiber and a later minimal level allowables program. It is expected that there will be no strength reduction when using SBCF in a cured laminate as was the case on the prior programs; this will be verified under the current program with material from the new BC3 stretch break line. Single tow SBCF spools will shortly be available for evaluation by potential prepreg manufacturers and other end users.
This paper documents the re-evaluation and updates to the previous Partial Regime Recognition Spectrum effort for the MH-47G using Structural Usage Monitoring System (SUMS). Further validation of the SUMS algorithm allowed for additions to the spectrum. These additions include more refined categorization of turn and partial power descent regimes based on angle of bank and descent rates, respectively; high load prorates for turns, partial power descents, level flight, and climbs based on the Cruise Guide Indicator; exceedances of maximum density altitude; and use of occurrences for Landing and Run-On Landing regimes. Additional years of flight data from 2013 to 2019 were included in this effort. The updated usage spectrum for the Army MH-47G aircraft has been delivered to the OEM (Original Equipment Manufacturer). The OEM calculated new fatigue lives and updated the "Fatigue Substantiation Report", which will soon be fielded.
Groove designs presented herein are applicable for use with machined or formed metal seals which are similar in configuration to those shown in figure 3, which operate under internal pressure or in vacuum service and which have been specifically qualified or recommended by the purchaser or the manufacturer for use with this AIR. They are also applicable for use with metal o-rings (e.g., MS9142, MS202 thru MS9205) where interchangeability with machined or formed metal seals is desired. For metal o-ring groove designs where inter-changeability is not a requirement refer to ARP 674.
As the U.S. Army endeavors to maintain overmatch capability in the global arena, Future Vertical Lift has become a high priority. In a climate that demands a more efficient and affordable acquisition process, it is imperative that structural integrity requirements are maintained as a priority to ensure initial quality, supportability, and maintainability considerations. Therefore, it is paramount that a standard practice be utilized so that structural integrity requirements are clearly understood by the Product Office, the Airworthiness Authority, and the Original Equipment Manufacturer(s). This paper highlights how the MIL-STD-3063 U.S. Army Standard Practice for Rotorcraft Structural Integrity Programs can meet these demands by laying out interrelated functional tasks in a concise manner to allow for decision makers to make sound choices with regards to structural integrity for any new developmental aircraft. The paper also details how the standard practice is being utilized to assist and guide Future Vertical Lift efforts.
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