In this study, the effectiveness of an alternative approach to temporarily repair an open-hole damaged Nomex honeycomb sandwich structure is experimentally investigated. The repair process consists of a resin-infused carbon fabric wet layup patch adhesively bonded to the facesheets and Airex structural foam used as a core replacement plug. The specimens of intact, damaged and repaired Nomex honeycomb sandwich panels are subjected to the quasi-static three-point bending test. The panel's flexural performances are determined by analyzing the obtained load-displacement responses. The effectiveness of the proposed repair technique is evaluated by comparing the responses of the repaired panels with the ones obtained from the intact and damaged panel specimens. The comparison is effectuated in terms of mean values of flexural elastic modulus, peak force, energy absorption, and specific energy absorption. In addition, the observed failure modes of the different panel configurations are pointed out and discussed.
CampbellFC. Structural composite materials. Materials Park, OH: ASM International, 2010.
2.
RašuoB. Aircraft production technology. Faculty of Mechanical Engineering. Belgrade: University of Belgrade, 1995, Serbian.
3.
DinulovicMRasuoBKrsticB, et al.3D random fiber composites as a repair material for damaged honeycomb cores. FME Transactions2013; 41: 325–332.
4.
Krzyzak A, Mazur M, Gajewski M, et al. Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties. Int J Aerosp Eng 2016; 2016: 7816912. DOI: 10.1155/2016/7816912
5.
MucANogowczykR. Formy zniszczenia konstrukcji sandwiczowych z okładzinami wykonanymi z kompozytów (Forms of sandwich constructions destruction with claddings made of composite). Composites2005; 5: 31–36. Polish.
6.
OchelskiSNiezgodaT. Kompozytowe konstrukcje pochłaniające energię uderzenia (Composite construction for striking energy absorption-review). Przegląd Mechaniczny2007; 1: 21–28. Polish.
7.
Herrmann AS, Zahlen PC and Zuardy I. Sandwich structures technology in commercial aviation. Sandwich Struct 7: Adv Sandwich Struct Mater 2005; 7: 13–26. DOI: 10.1007/1-4020-3848-8_2
8.
Hart-SmithL. Adhesive-bonded scarf and stepped-lap joints. Hampton: VA: Langley Research Center, 1973, Tech. Rep. NASA CR 112237.
9.
ArmstrongKB. Efforts to standardize aerospace composite repairs, 1988–2003. Proc IMechE, Part G: J Aerospace Engineering2003; 217: 223–236.
10.
KatnamKBDa SilvaLFMYoungTM. Bonded repair of composite aircraft structures: a review of scientific challenges and opportunities. Prog Aerosp Sci2013; 61: 26–42.
11.
ParkHKongC. Experimental study on barely visible impact damage and visible impact damage for repair of small aircraft composite structure. Aerosp Sci Technol2013; 29: 363–372.
12.
CamineroMAPavlopoulouSLopez-PedrosaM, et al.Analysis of adhesively bonded repairs in composites: damage detection and prognosis. Compos Struct2013; 95: 500–517.
13.
ArikanVKarakuzuRAlpyildizT. Improvement of load carrying capacity of sandwich composites by different patch repair types. Polym Test2018; 72: 257–262.
14.
KawakamiHFeraboliP. Lightning strike damage resistance and tolerance of scarf-repaired mesh-protected carbon fiber composites. Composites Part A: Appl Sci Manuf2011; 42: 1247–1262.
15.
ParkHKongC. A study on low velocity impact damage evaluation and repair technique of small aircraft composite structure. Composites Part A: Appl Sci Manuf2011; 42: 1179–1188.
16.
LiCZhaoQYuanJ, et al.Simulation and experiment on the effect of patch shape on adhesive repair of composite structures. J Compos Mater2019; 53: 4125–4135.
17.
ZhangTYanYJinC. Experimental and numerical investigations of honeycomb sandwich composite panels with open-hole damage and scarf repair subjected to compressive loads. J Adhes2016; 92: 380–401.
18.
LiuSGuanZGuoX, et al.Process factors and edgewise compressive properties of scarf-repaired honeycomb sandwich structures. Appl Compos Mater2014; 21: 689–705.
19.
BendemraHCompstonPCrothersPJ. Optimisation study of tapered scarf and stepped-lap joints in composite repair patches. Compos Struct2015; 130: –8.
20.
Park H. Investigation on repairable damage tolerance for structural design of aircraft composite structure. J Compos Mater 2016; 50: 0021998316643579. DOI:10.1177/0021998316643579
21.
Joosten MW, Neave MB, Rider AN, et al. 3D Printed continuous fibre composite repair of sandwich structures. Compos Struct 2022; 290: 115518. DOI:10.1016/j.compstruct.2022.115518
22.
DuPontTM. Nomex® fiber Technical guide, 2019.
23.
Faserverbundwerkstoffe® Composite Technology. Technical Data of Carbon fabric prepreg 200 g/m2, 2017.
24.
ASTM C 393/C 393M-16. Standard test method for core shear properties of sandwich constructions by Beam Flexure, ASTM International, West Conshohocken, PA, 2016.
FibermaxTM, Mechanical properties of Nomex aramid honeycomb Thickness 25 mm Cell size 3.2 mm, https://www.fibermaxcomposites.com/ (2022, accessed 5 February 2022).
XieSFengZZhouH, et al.Three-point bending behavior of Nomex honeycomb sandwich panels: experiment and simulation. Mech Adv Mater Struct2021; 28: 1917–1931.
GiglioMGilioliAManesA. Numerical investigation of a three point bending test on sandwich panels with aluminum skins and Nomex™ honeycomb core. Comput Mater Sci2012; 56: 69–78.
39.
CastanieBBouvetCGinotM. Review of composite sandwich structure in aeronautic applications. Composites Part C: Open Access2020; 1: 100004.
