Enhancement of seal life through carbon composite back-up rings under shock loading conditions in defence applications

Under shock-loading, twinning is observed in metals that do not twin under conventional loading conditions, for example copper and nickel where the stacking fault energy is about 78 and 128 ergs/cm2, respectively. Contradictions in the published data on the twinning stress in copper (from 1.6 GPa in thin films to 14.5-20 GPa in bulk specimens suggest differences associated with experimental techniques. This study examines the role of residual plastic strain (eres) on the deformation substructures, particularly twinning, in shock-roaded copper.

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Effects of microstructure and shock loading conditions on the damage behavior of polycrystalline copper

EPJ Web of Conferences ◽

10.1051/epjconf/20122602008 ◽

2012 ◽

Vol 26 ◽

pp. 02008 ◽

Cited By ~ 4

Author(s):

J.P. Escobedo ◽

E.K. Cerreta ◽

D. Dennis-Koller ◽

B.M. Patterson ◽

R.A. Lebensohn ◽

...

Keyword(s):

Shock Loading ◽

Polycrystalline Copper ◽

Loading Conditions ◽

Damage Behavior

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Modeling and simulation of carbon composite ballistic and blast behavior

Journal of Composite Materials ◽

10.1177/0021998319866902 ◽

2019 ◽

Vol 54 (4) ◽

pp. 485-499

Author(s):

Chian-Fong Yen ◽

Bob Kaste ◽

Charles Chih-Tsai Chen ◽

Nelson Carey

Keyword(s):

Composite Material ◽

Progressive Failure ◽

Laminated Composite ◽

Blast Loading ◽

Carbon Composite ◽

Ballistic Impact ◽

Failure Behavior ◽

Loading Conditions ◽

Failure Model ◽

Carbon Composite Material

The design of the next generation of aeronautical vehicles is driven by the vastly increased cost of fuel and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aeronautical structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic impact and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic impact and blast loading conditions. Using a meso-mechanics approach, a laminated composite is represented by a collection of selected numbers of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by the strain-rate-dependent layer progressive failure model using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA® as a user-defined material subroutine. In this paper, the ballistic limit velocity (V50) was first established for a series of laminates by ballistic impact testing. Correlation of the predicted and measured V50 values has been conducted to validate the accuracy of the ballistic modeling approach for the selected carbon composite material. A series of close-in shock hole blast tests on carbon composite panels were then tested and simulated using the LS-DYNA® Arbitrary-Lagrangian-Eulerian (ALE) method integrated with the Army Research Laboratory (ARL) progressive failure composite model. The computational constitutive model has been validated to characterize the progressive failure behavior in carbon laminates subjected to close-in blast loading conditions with reasonable accuracy. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic impact and blast survivability.

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Large Engine Hybrid Ceramic Bearings

Volume 2: Aircraft Engine; Marine; Microturbines and Small Turbomachinery ◽

10.1115/94-gt-264 ◽

1994 ◽

Cited By ~ 2

Author(s):

Mark A. Rhoads ◽

Manohar Bashyam ◽

William J. Crecelius

Keyword(s):

Condition Monitoring ◽

High Speed ◽

Shock Loading ◽

Monitoring Device ◽

Loading Conditions ◽

Large Engine ◽

Bearing Condition Monitoring ◽

Rolling Elements ◽

Hybrid Bearing ◽

Full Scale Tests

General Electric Aircraft Engines under contract from the Advanced Research Projects Agency (ARPA), has demonstrated the ability of ceramic rolling elements to withstand shock loading conditions experienced during race spalling, has performed a series of full scale tests directed at showing the thermal benefit of large hybrid bearings at speeds up to 3.0 MDN, and has developed a condition monitoring device that detects both ceramic and metallic bearing debris. The details of the three primary tasks are presented in this paper: Task 1 involves the testing of a hybrid bearing operating in severe shock loading conditions, with comparisons to an all steel bearing. Task 2 involves back-to-back comparison of an all-steel high speed bearing to a hybrid bearing of the same geometry and to a hybrid bearing of tighter race curvatures, showing differences between outer ring temperatures of all-steel and hybrid bearings. Task 3 deals with the bench testing of a new ultrasonic bearing condition monitoring device, designed to collect and detect both ceramic or metallic debris.

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