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Flexural failure of notched curved composite beams
The objective of this work was to develop and test an analytical technique which would predict the tensile failure of a notched curved composite beam loaded in bending. This technique was developed by modifying the Damage Zone Model (DZM), a composite failure theory originally developed for the tensile failure of notched composite laminates. A number of composite applications, especially aerospace applications, involve the use of curved beams, many of which are notched. A method to predict the failure loads of notched composite beams of general cross sections and different notch geometries would provide an important tool for the design of such structures. In order to verify the analytical technique, notched curved J beams made of long discontinuous fiber laminate were tested in bending to failure. To predict the failure of these beams with the DZM, the material properties required by the DZM of the long discontinuous fiber laminate were determined. The unnotched tensile strength of the (+/-45/90+/-45/0)s laminate was determined to be 63840 psi and the apparent fracture energy, 324 psi-inch. After obtaining the needed parameters for the DZM, an experimental technique was developed to test notched curved J beams in four-point bending to failure. Experimental strengths were compared to DZM strength predictions and results from the investigation showed that: In-plane tensile failure of notched J beams loaded in bending was difficult to achieve due to out-of-plane deflections. DZM strength predictions were within 17.8 % of the assumed moment to initial failure and within 37.8 % of the moment to final failure. Out-of-plane deflections which reduced the initial stiffness of notched curved beams made comparisons with DZM strength predictions of questionable value. Future investigations are warranted to further examine the accuracy of the model. Current results may be considered questionable due to out-of-plane deflections experienced by the notched curved J during the experiments which cannot be accounted for in the current DZM formulation. A simple method to investigate the accuracy of the DZM would be to conduct tests with simpler beam cross sections in order to reduce or eliminate the out-of-plane deflections.
Flexural failure of notched curved composite beams
The objective of this work was to develop and test an analytical technique which would predict the tensile failure of a notched curved composite beam loaded in bending. This technique was developed by modifying the Damage Zone Model (DZM), a composite failure theory originally developed for the tensile failure of notched composite laminates. A number of composite applications, especially aerospace applications, involve the use of curved beams, many of which are notched. A method to predict the failure loads of notched composite beams of general cross sections and different notch geometries would provide an important tool for the design of such structures. In order to verify the analytical technique, notched curved J beams made of long discontinuous fiber laminate were tested in bending to failure. To predict the failure of these beams with the DZM, the material properties required by the DZM of the long discontinuous fiber laminate were determined. The unnotched tensile strength of the (+/-45/90+/-45/0)s laminate was determined to be 63840 psi and the apparent fracture energy, 324 psi-inch. After obtaining the needed parameters for the DZM, an experimental technique was developed to test notched curved J beams in four-point bending to failure. Experimental strengths were compared to DZM strength predictions and results from the investigation showed that: In-plane tensile failure of notched J beams loaded in bending was difficult to achieve due to out-of-plane deflections. DZM strength predictions were within 17.8 % of the assumed moment to initial failure and within 37.8 % of the moment to final failure. Out-of-plane deflections which reduced the initial stiffness of notched curved beams made comparisons with DZM strength predictions of questionable value. Future investigations are warranted to further examine the accuracy of the model. Current results may be considered questionable due to out-of-plane deflections experienced by the notched curved J during the experiments which cannot be accounted for in the current DZM formulation. A simple method to investigate the accuracy of the DZM would be to conduct tests with simpler beam cross sections in order to reduce or eliminate the out-of-plane deflections.
Flexural failure of notched curved composite beams
Biegeversagen von gekerbten gekrümmten Verbundträgern
Cheeseman, B.A. (author) / Santare, M.H. (author) / O'Toole, B.J. (author)
Engineering Fracture Mechanics ; 54 ; 479-498
1996
20 Seiten, 16 Bilder, 2 Tabellen, 19 Quellen
Article (Journal)
English
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