Evaluation of the compressive response of notched composite panels using a full-field displacement measurement system

McGowan, David M.; Ambur, Damodar R.; Hanna, Ty; McNeill, Stephen R.

doi:10.2514/6.1999-1406

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…A limited number of specimens are also loaded in the test frame while being monitored by the DIC system, VIC-3D provided by Correlated Solutions Inc. The system consists of two high-resolution cameras and an image analysis computer program capable of measuring large displacements and strains [12,13]. The specimen is typically coated with a white spray paint, and a random pattern of black speckle marks is applied to the surface to be analyzed.…”

Section: Materials Fabrication and Test Setupmentioning

confidence: 99%

Modulus Measurement for Prepreg-based Discontinuous Carbon Fiber/Epoxy Systems

Feraboli

Peitso

Cleveland

et al. 2009

Journal of Composite Materials

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The elastic modulus of discontinuous carbon fiber/epoxy laminates produced by compression molding of chopped unidirectional prepreg tape is measured by several means. Commercial applications for this type of material form already exist, such as Hexcel HexMC Õ . Although the average elastic modulus of this material has been shown to be as high as that of the continuous fiber quasiisotropic benchmark, its non-homogenous nature gives rise to variations as high as 19% in the measurement by means of strain gage or extensometer. This phenomenon would be attributed to the variability of the manufacturing process, were it not for the fact that strength variation is much lower, with a maximum of 9%. In order to assess whether the variation observed is a result of the measurement technique and not an actual variation in material properties, a series of tensile tests is conducted while systematically varying strain gage length and location. The measurements are then compared relative to each other as well as to multiple extensometer readings along the length and opposite sides of the specimen. Digital image correlation (DIC) technique is used to gain further insight on the observed phenomena, and it has shown to be fundamental to obtain a full-field strain measurement, which is more repeatable than any of the traditional measurement techniques. Furthermore, DIC shows that complex strain distributions exist on the surface of the specimen, varying greatly along the width and across the length of the specimen, and these are associated to the non-homogeneous nature of the sub-structure.

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Section: Materials Fabrication and Test Setupmentioning

confidence: 99%

Modulus Measurement for Prepreg-based Discontinuous Carbon Fiber/Epoxy Systems

Feraboli

Peitso

Cleveland

et al. 2009

Journal of Composite Materials

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“…A selected number of specimens that were impact-damaged are also cross-sectioned, polished and inspected both visually and with the aid of a microscope to determine the extent of facesheet and core damage at different impact energy levels. [34]. The specimen is typically coated with a white spray paint, and a random pattern of black speckle marks is applied to the surface to be analyzed.…”

Section: Materials and Experimental Setupmentioning

confidence: 99%

Damage Resistance Characteristics of Thick-Core Honeycomb Composite Panels

Feraboli

2006

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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The quasi-static indentation and impact response of very thick sandwich panels, developed as candidate materials for the crown panel of the next generation large commercial transport, is described. A preliminary characterization of the damage resistance of eight different corefacesheet configurations is performed, and the effect of facesheet thickness, core density and core material is investigated. Drop weight impact, quasi-static indentation, and quasi-static core-crushing characteristics of the different core panel configurations have been studied. Damage is evaluated using conventional methods including cross-sectioning and visual inspection, and dent depth is measured by means of an automated high-precision depth gage. The indentation profile is monitored by means of the digital image correlation technique during the quasi-static tests to gain insight in the response of these complex structures. Excellent agreement has been found between the quasi-static and impact test on the basis of the recorded contact force profiles.

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“…The STAGS post-buckling capability was used on bladestiffened and PRSEUS panels. 1,[3][4][5][6][7][8][9][11][12][13][1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]20 Examples of these specimens are shown in Fig. 6 …”

Section: A Predicting Post-bucking Behaviormentioning
confidence: 99%

“…Buckling analyses are typically conducted on compression-loaded specimens to determine the bifurcation buckling load and initial mode shape but nonlinear analysis is often required to determine how much load the structure will carry and quantify its post-buckling behavior since stitched structure has demonstrated an ability to support load beyond buckling. 4,6,[11][12][13][14][15][16][17][18][19][20] Nonlinear analysis can be conducted until collapse is reached and this result is compared to test data.…”

Section: Modeling and Analyzing Stitched Structures In Stagsmentioning
confidence: 99%

The Use of the STAGS Finite Element Code in Stitched Structures Development
Jegley
¹
,
Lovejoy
²

2014
55th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference
0
0
0
0
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In the last 30 years NASA has worked in collaboration with industry to develop enabling technologies needed to make aircraft more fuel-efficient and more affordable. The focus on the airframe has been to reduce weight, improve damage tolerance and better understand structural behavior under realistic flight and ground loading conditions. Stitched structure is a technology that can address the weight savings, cost reduction, and damage tolerance goals, but only if it is supported by accurate analytical techniques. Development of stitched technology began in the 1990's as a partnership between NASA and Boeing (McDonnell Douglas at the time) under the Advanced Composites Technology Program and has continued under various titles and programs and into the Environmentally Responsible Aviation Project today.These programs contained development efforts involving manufacturing development, design, detailed analysis, and testing. Each phase of development, from coupons to large aircraft components was supported by detailed analysis to prove that the behavior of these structures was well-understood and predictable. The Structural Analysis of General Shells (STAGS) computer code was a critical tool used in the development of many stitched structures. As a key developer of STAGS, Charles Rankin's contribution to the programs was quite significant. Key features of STAGS used in these analyses and discussed in this paper include its accurate nonlinear and post-buckling capabilities, its ability to predict damage growth, and the use of Lagrange constraints and follower forces.

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Evaluation of the compressive response of notched composite panels using a full-field displacement measurement system

Cited by 5 publications

References 6 publications

Modulus Measurement for Prepreg-based Discontinuous Carbon Fiber/Epoxy Systems

Modulus Measurement for Prepreg-based Discontinuous Carbon Fiber/Epoxy Systems

Damage Resistance Characteristics of Thick-Core Honeycomb Composite Panels

The Use of the STAGS Finite Element Code in Stitched Structures Development

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