Crashworthy Behaviour of Thin-Walled Tubes of Fibreglass Composite Materials Subjected to Axial Loading

Abstract The increasing application of composite materials in the construction of machines causes strong need for modelling and evaluating their strength. There are many well known hypotheses used for homogeneous materials subjected to monotone and cyclic loading conditions, which have been verified experimentally by various authors. These hypotheses should be verified also for composite materials. This paper provides experimental and theoretical results of such verifications for bimaterial structures with interfacial cracks. Three well known fracture hypotheses of: Griffith, McClintock and Novozhilov were chosen. The theoretical critical load values arising from each hypotheses were compared with the experimental data including uni and multi-axial loading conditions. All tests were carried out with using specially prepared specimens of steel and PMMA.

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Dynamic Behavior of Aircraft Wings Modeled as Doubly-Tapered Composite Thin-Walled Beams

10.1115/imece1999-0615 ◽

1999 ◽

Author(s):

Sungsoo Na ◽

Liviu Librescu

Keyword(s):

Composite Materials ◽

Free Vibration ◽

Dynamic Response ◽

Dynamic Behavior ◽

Transverse Shear ◽

Dynamical Behavior ◽

Time Dependent ◽

Aircraft Wings ◽

Helicopter Blades ◽

Thin Walled

Abstract A study of the dynamical behavior of aircraft wings modeled as doubly-tapered thin-walled beams, made from advanced anisotropic composite materials, and incorporating a number of non-classical effects such as transverse shear, and warping inhibition is presented. The supplied numerical results illustrate the effects played by the taper ratio, anisotropy of constituent materials, transverse shear flexibility, and warping inhibition on free vibration and dynamic response to time-dependent external excitations. Although considered for aircraft wings, this analysis and results can be also applied to a large number of structures such as helicopter blades, robotic manipulator arms, space booms, tall cantilever chimneys, etc.

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Investigation of Composite Hydrodynamic Thrust Bearing Operating Temperature Under Varying Axial Loads

Volume 4A: Dynamics, Vibration, and Control ◽

10.1115/imece2017-70410 ◽

2017 ◽

Author(s):

Kyle Myers ◽

Collier Fais ◽

Matthew Zacharias ◽

Muhammad Ali ◽

Khairul Alam

Keyword(s):

Composite Materials ◽

Operating Temperature ◽

Sampling Rate ◽

Axial Loading ◽

Axial Loads ◽

Axial Thrust ◽

Thrust Bearings ◽

Average Operating ◽

Thrust Load ◽

Proper Movement

The purpose of this experiment was to explore the operational behavior of hydrodynamic thrust bearings machined from various composite materials (PTFE-Filled Delrin Acetal Resin and MDS-Filled Nylon) and general Aluminum under a set of different axial loading conditions. Since thrust bearings allow mechanical components subjected to axial loads to rotate more freely, they must counter a great deal of friction which can cause bearing failure in order to maintain proper movement. In order to reduce friction and weight, this research posits that thrust bearings machined from composite materials of lower friction coefficients and densities to that of conventionally used materials such as aluminum may provide some advantages. This hypothesis was tested by machining three thrust bearings, all to the same geometric specifications (two composites and one Aluminum) and subjecting them to thrust loads of 25, 50, 75, and 100 pounds while rotating them at a constant rotational speed of 3050 RPM for 10 minutes at each load using a customized test rig. A thermocouple implanted into the bearings themselves recorded the operation temperatures at a sampling rate of 20 Hz. Based on the average temperatures recorded at the 100 pound axial/thrust load, the experiments suggest that the PTFE-Filled Delrin Acetal maintains the lowest average operating temperature of 29.5 °C, followed by the MDS-Filled Nylon at 41.6 °C and lastly the Aluminum at 54.4 °C — a trend that is observed at each axial load albeit less pronounced. These results suggest that composite materials such as PTFE-Filled Acetal and MDS-Filled Nylon to be used in lieu of conventional metals and operate at lower temperatures and lower friction.

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