The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform

P. Chang - One of the best experts on this subject based on the ideXlab platform.

  • Hybrid approaches for aircraft primary structure repairs
    Composite Structures, 2019
    Co-Authors: J. Wang, A. Baker, P. Chang
    Abstract:

    Abstract Currently bonded repairs can only be permitted on those aircraft primary structures suffering cracks/damages having a residual strength well exceeding the Design Limit Load prior to application of the bonded repairs. This paper focuses on the approaches to meet the certification requirement by combining a bonded patch with other methods that enhance residual strength of the damaged structures. An overview of the recent research in this area conducted by Defence Science and Technology Group and its research partner organisations is presented. The outcomes from six individual research programs indicated the hybrid repair methods are promising for primary structure repair applications. Significant residual strength increases were achieved through optimum damage removal and/or inclusion of alternative Load paths. These methods also provide significant additional fatigue life post premature bond failure that would allow any possible bond-line defect/damage to be identified by NDI means long before a catastrophic failure. The adhesive bond in the hybrid repairs was proven to provide significant benefit in enhancing the static strength and fatigue resistance. Key issues for the application of these hybrid repair methods and future research directions are also discussed.

Hiroshige Kikukawa - One of the best experts on this subject based on the ideXlab platform.

  • fatigue test of lightweight composite wing structure
    International Journal of Fatigue, 2006
    Co-Authors: Yuichiro Aoki, Takashi Ishikawa, Shinichi Takeda, Yuichi Hayakawa, Atsushi Harada, Hiroshige Kikukawa
    Abstract:

    Fatigue tests of hat-shape stringer stiffened panel are conducted, where this panel is a typical part of upper skin of lightweight composite wing using new production technology of stitching, co-bonding and RTM method. Impact damages are applied on skin/stringer co-bonded part and typical skin part of the test panel by drop-weight impact machine. There are two phases in the present test. The first phase is fatigue tests to verify durability of the structure with barely visible impact damages. The second phase is flaw growth tests for evaluation of visible impact damage growth to estimate inspection intervals. The Mini-TWIST (shortened version of The Transport WIng STandard Load program) spectrum Loading is used for both tests. Non-destructive inspection is carried out by pulsed thermography during the test to observe damage propagation. Finally, static Load is applied up to Design Limit Load to verify the residual strength after all the spectrum Loading tests.

Dawn C. Jegley - One of the best experts on this subject based on the ideXlab platform.

  • Structural Efficiency of Stitched Rod-Stiffened Composite Panels with Stiffener Crippling
    49th AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference <br> 16th AIAA ASME AHS Adaptive Structures Conference<br, 2008
    Co-Authors: Dawn C. Jegley, Alexander Velicki, Daniel A. Hansen
    Abstract:

    The structural efficiency of rod-stiffened stitched specimens is evaluated to determine their weight saving potential if the stiffeners were allowed to buckle at less than or equal to Design ultimate Load. Analytical and experimental results from rod-stiffened and blade-stiffened single-stiffener specimens are presented. In both cases, skin and flanges were stitched together through-the-thickness prior to curing. No mechanical fasteners were used for the assembly. Specimens were Loaded to failure in axial compression. Failure modes are discussed. Finite element and experimental results agree for the response of the structures. For some specimen configurations, improved structural efficiency can be obtained by allowing stiffeners to buckle at Design Limit Load rather than requiring that buckling not occur prior to Design ultimate Load. In addition, through-the-thickness stitching can change the failure mechanism by suppressing delamination between skin and flange. A parametric study is presented herein which describes the possible weight savings with this approach.

  • Structural Efficiency of Stitched Composite Panels with Stiffener Crippling
    Journal of Aircraft, 2005
    Co-Authors: Dawn C. Jegley
    Abstract:

    The structural efficiency of blade-stiffened stitched specimens is compared to determine their weight-saving potential if blades were allowed to buckle at less than or equal to Design ultimate Load. Analytical and experimental results from four configurations of crippling specimens are presented. Specimen skin and blades were held together with through-the-thickness stitches prior to curing. No mechanical fasteners were used for the assembly. Tests were conducted with and without low-speed impact damage. Failure modes are discussed. Finite element and experimental results agree for the response of the structures. For some specimen configurations, improved structural efficiency can be obtained by allowing stiffeners to buckle at Design Limit Load rather than requiring that buckling not occur prior to Design ultimate Load. A parametric study is presented herein, which describes the possible weight savings with this approach.

Yuichiro Aoki - One of the best experts on this subject based on the ideXlab platform.

  • Durability and Damage Tolerance Evaluation of VaRTM Composite Wing Structure
    ICAF 2011 Structural Integrity: Influence of Efficiency and Green Imperatives, 2011
    Co-Authors: Yuichiro Aoki, Yoshiyasu Hirano, Sunao Sugimoto, Yutaka Iwahori, Yosuke Nagao, Takeshi Ohnuki
    Abstract:

    Durability and damage tolerance of subcomponent and full-scale wing box structure fabricated by VaRTM are evaluated. Fatigue spectrum with Load enhancement factor was applied to the test articles for 1 DSO of 40,000 flights. The Mini-TWIST fatigue spectrum is used for both tests. Then, impact damages are given to the skin stiffened by co-cured stringer and typical skin part by drop-weight to create the delamination. After that, impact damage growth is evaluated during 1 DSO fatigue spectrum and optimal inspection interval is examined. Finally, residual strength of structures is verified by ultimate Load test with 150% Design Limit Load. Applied strain level for Subcomponents are intentionally higher than original one in order to evaluate the structural performance in more critical condition. Non-destructive inspection is carried out by 3D ultrasonic scan system with multiple-array sensors to evaluate delamination growth. In Subcomponent test, stringer run-out shows local out-of-plane deformation and that causes disbonding of stringer termination. The disbonding area gradually increases during 1 DSO fatigue test. However, the structure did not show any degradation of structural performance. The damage tolerance tests verify that impact-induced delaminations have not grown throughout the 1 DSO. In the final ultimate Load test, the Load bearing-capabilities of present VaRTM wing structure have been verified and the structure could survive for 4 seconds without any detrimental deformation and damage growth.

  • fatigue test of lightweight composite wing structure
    International Journal of Fatigue, 2006
    Co-Authors: Yuichiro Aoki, Takashi Ishikawa, Shinichi Takeda, Yuichi Hayakawa, Atsushi Harada, Hiroshige Kikukawa
    Abstract:

    Fatigue tests of hat-shape stringer stiffened panel are conducted, where this panel is a typical part of upper skin of lightweight composite wing using new production technology of stitching, co-bonding and RTM method. Impact damages are applied on skin/stringer co-bonded part and typical skin part of the test panel by drop-weight impact machine. There are two phases in the present test. The first phase is fatigue tests to verify durability of the structure with barely visible impact damages. The second phase is flaw growth tests for evaluation of visible impact damage growth to estimate inspection intervals. The Mini-TWIST (shortened version of The Transport WIng STandard Load program) spectrum Loading is used for both tests. Non-destructive inspection is carried out by pulsed thermography during the test to observe damage propagation. Finally, static Load is applied up to Design Limit Load to verify the residual strength after all the spectrum Loading tests.

Heinz Voggenreiter - One of the best experts on this subject based on the ideXlab platform.

  • Effects of static preLoads on the high velocity impact response of composite plates
    Composite Structures, 2016
    Co-Authors: Dominik Schueler, Nathalie Toso-pentecote, Heinz Voggenreiter
    Abstract:

    The paper discusses a high velocity impact scenario where representative fuselage composite plates are statically preLoaded and then impacted with a blunt impactor at velocities in the range 70–105 m/s. Compression and tension preLoads that represent Design Limit Load were considered as well as lower preLoads that a structure would carry more frequently. Gas gun impact tests were performed to generate a validation database for comparison with results from numerical simulation. A modelling methodology to simulate preLoads and transient impact events was documented. The numerical model captures intra- and inter-ply damage by using layers of shell elements connected with cohesive interface layers. Both test and simulation results indicate an influence of static preLoads on the impact damage response. The numerical model was especially used to better understand the interaction between preLoads and dynamic impact Loads which are complex especially for impact on buckled plates.