The behavior of Aluminium Carbon/Epoxy fibre metal laminate under quasi-static loading

Transcription

1 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 The behavior of Aluminium Carbon/poxy fibre metal laminate under quai-tatic loading N K Romli *, M R M Rejab, D Bachtiar, J Siregar, M F Rani, W S W Harun, Salwani Mohd Salleh and M N M Merzuki Structural Material & Degradation Focu Group, Faculty of Mechanical ngineering, Univeriti Malayia Pahang, 66 Pekan, Pahang, Malayia Faculty of ngineering, DRB-Hicom Univerity of Automotive Malayia, 667 Pekan, Pahang, Malayia * Correponding author khaleedaromli@gmail.com Abtract. One of major concern that related to the flight afety i impact of bird. To minimize the rik, there i need to increae the impact reitance of aircraft by developing a new material and ha the good tructural deign of aircraft tructure. The hybrid laminate are potential candidate material to be apied for the aircraft tructure uceptible to bird trike. The fibre metal laminate wa fabricated by a compreion moulding technique. The carbon fibre and aluminium alloy 4- wa laminated by uing thermoet epoxy. A compreion moulding technique wa ued for the FML fabrication. The aluminium heet metal ha been roughening by a metal anding method which to improve the bonding between the fibre and metal layer. The main objective of thi paper i to determine the failure repone of the laminate under five variation of the crohead diacement in the quai-tatic loading. The FML wa modelled and analyed by uing xicit olver. Baed on the experimental data of the quai-tatic tet, the reult of mm/min wa.85 kn and higher than 5,, 5 and mm/min which becaue of the aluminium ductility during the impact loading repone. The numerical imulation were generally in good agreement with the experimental meaurement.. Introduction A fibre metal laminate (FML) or alo known a a hybrid laminate contain metal layer and compoite material [-5]. The fibre metal laminate can be apied to many apication becaue of the fibre metal laminate can withtand to the impact, loading and harh environment for a long period. The combination of the metal layer and compoite fibre produce uperior characteritic uch a fatigue and fracture. Beide that, the ubtitution of both material are to reduce the weight of the aircraft tructure and aving in oil conumption [5-]. The Glare and Arall are member of fibre metal laminate. The fibre metal laminate tarted and apied in military apication after the Second World War [-3]. From the poitive feedback of the apication, the fibre metal laminate began the apication widely in aircraft tructure uch a fuelage and wing [4, 5]. The exame of the apication i in the Airbu A38 due Content from thi work may be ued under the term of the Creative Common Attribution 3. licence. Any further ditribution of thi work mut maintain attribution to the author() and the title of the work, journal citation and DOI. Publihed under licence by Ltd

2 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 to the improvement in fatigue, reitance to corroion and impact and weight reduced nearly 794 kg [6-9]. The other organiation uch a NASA, Bombardier and MBRAR intereted with the ubtitution of the aluminium in a fibre metal laminate. The high trength and tiffne are a good combination and reulted in great performance in pace apication []. An autoclave commonly ued in manufacturing o fibre metal laminate or curing proce at a high preure. The curing temperature hould be maintained a well. The FML need to be proceed up to C a to avoid damage on the aluminium alloy 4-T3. The temperature will allow an exce of rein flow out and reduced it vicoity. The preure will pre and conolidate the ie then uppre the void [3, 3-36]. The hear thickening fluid i a combination of hard metal oxide particle which upended in the liquid polymer. The STF can lead the laminate to improve reitance from ballitic impact damage [37]. The debonding proce between a heet metal layer and compoite fibre layer, delamination of the compoite layer, fracture due to a aticity behaviour of a metal are commonly happened to a fibre metal laminate tructure which becaue of the impact of a load and depended on the layup configuration [6,,, 38-4]. The proce of curing by uing an autoclave will take long hour of proceing and required intenive of labour cot for the whole production [9, 4]. The purpoe of thi paper to invetigate the failure behaviour through an experiment of quai-tatic impact tet and predict the failure behaviour by uing Abaqu/xicit.. xperimental work The behaviour of a fibre metal laminate wa tudied baed on the aluminium alloy 4- heet and unidirectional carbon fibre prepreg. The prepreg fibre wa bonded with the two heet metal layer. The urface of the aluminium alloy wa treated through a metal anding. The grit ize of and paper i. The purpoe of the metal anding i for urface roughne. The urface roughne will increae the bonding trength between the heet metal and gla fibre. The layup configuration of the FML i /. The ize and thickne of the FML are 5 mm x 5 mm and.5.5 mm. The FML wa fabricated by a compreion moulding technique. The gla fibre and aluminium alloy heet metal alloy laminated by uing the thermoet epoxy. A preure wa apied by acing a moderated load on it and cured in at room temperature for 4 hour. The hape and ize of the indenter are hemiphere and.7 mm. The indenter fabricated through a machining proce which i a CNC machine. The coolant wa apied during the machining proce a to reduce the cutting force temperature of the machining proce.

3 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 Hemiphere noe Figure. The etup for quai-tatic tet. L = 7 mm D =.7 mm Figure. Hemipherical indenter. 3. Computational model The alternative way to predict the experimental reult i by uing numerical analyi. Study of numerical analyi on fibre metal laminate became crucial a to know impact behaviour of it. The proce of imulation could be done by adding the propertie material ued uch a Young modulu, Poion ratio, the denity of the material and o on. The imulation proce required reaonable number of tructural tet for a validation proce. The previou reearcher have combined two theorie of failure criteria and aticity a to imulate the degradation behaviour of the ate and tudy the behaviour of the nonlinear numerical model. The damage of an impact wa controlled by degradation of the tiffne and fracture wa becaue of energy releae which aimed to delamination growth. The imulation of 3

4 th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering 57 (7) 46 doi:.88/ x/57//46 deformation proce of 3D F model involved enitivity of train-rate and large change in tranvere compreion. The damaged of compoite ie cannot be ued directly in Abaqu [4]. The Abaqu/xicit wa ued to develop a numerical imulation of the FML under the low-velocity impact. The FML conited with two different of contituent material; 4- and unidirectional prepreg carbon fibre. The failure of the FML depended on the ductility of the material. 3.. Modelling of the 4- by uing Iotropic The aluminium alloy 4- wa modelled by uing an iotropic elatoaticity to predict elatic and atic behaviour either a a rate-dependent or rate dependent model and it ha a ime form. 3.. laticity A model of iotropic linear elaticity wa generated for the elatic repond for a material in a numerical analyi. The material that performed the linear elatic behavior, the total tre defined through thi an equation: el el D () Where the total tre, el D i the fourth order of an elaticity tenor and el i the total elatic train. From the quation () the tre-train relationhip of iotropic linear elaticity train: () The ymbol of i a Young modulu and i a Poion ration. Thee have been defined in the equation above. The invere relationhip defined a an equation below: G G G (3)

5 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 G (4) G i a hear modulu. The elatic material in the propertie of aluminium 4- wa ued in the numerical modelling. The propertie were taken from experimental reult. The value of Young modulu, 7. 6 GPa and the Poion ratio i Yielding An iotropic yielding i apied to a von Mie yield urface. The urface i aumed that yielding of a metal i independent where the obervation wa confirmed by experimental work. The metal wa apied under a poitive preure tre. When the metal apied in that kind of ituation which high-preure tre, it may be inaccurate becaue void can nucleate and grow in the metal Platicity Beyond the yield point i a permanent deformation or called a the atic behavior of the aluminium. The atic behavior i defined in an iotropic hardening. To decribe the iotropic hardening, the yield tre, which given in a atic train tabular function. The interpolation of the yield tre at any atic train rate can be done from the table of data. The data will remain contant when it reached to the lat value that ha been given in the table. Decompoition of the total increment of train defined a below: d el d de (5) For rate-dependent of material the relationhip of the equivalent atic train rate, followed by the uniaxial flow rate definition a: q,, (6) known a a function, q i the von Mie equivalent tre, and r i the temperature. r i an equivalent of the atic train 3..4 Failure Criteria The development of damage and failure of ductile material are ued in Abaqu/xicit to model the damage behavior of the aluminium. *SHAR FAILUR and *TNSIL FAILUR or a combination of both are two material failure model will offer in the Abaqu to account the damage and failure in a ductile metal. To calculate the failure, hear and tenile failure model can ue an equivalent of the atic train and hydrotatic cut-off tre repectively. If the failed mehe removed from the mehe it may for both failure model Damage for Ductile Metal There i two mechanim for the ductile metal will be ued in thi tudy; ductile damage and hear damage model. The ductile fracture or ductile damage i an initial criterion for predicting the onet damage which due to nucleation, growth and the void. Thi model will active when the following condition i atified: d D (7), D 5

6 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 D i a tate variable that increae monotonically with atic deformation. The model i aumed that the equivalent atic train at the onet of damage, i a function of triaxiality, p / q, and the D equivalent of atic train,. Note that p i the preure tre and q i the Mie equivalent tre. The hear damage model i a fracture which due to hear band localiation in the ductile metal. The model will active when the following condition i atified: d, (8) i a tate variable that increae monotonically with atic deformation and i relative to the incremental change in equivalent atic train,. The model i aumed that the equivalent atic train at the onet of damage, equivalent atic train rate, (k =.3 for the aluminium alloy) [43]. i a function of the hear tre ratio, q k p/ max. Note that max and the i the maximum hear tre k i a material parameter 3. Modelling of the compoite by Hahin damage criterion. The modelling for the compoite material, woven fabric carbon fibre reinforced atic wa followed baed on the table below: Table : Propertie of woven CFRP Property Symbol Value Young modulu in longitudinal direction (GPa) 48 Young modulu in tranvere direction (GPa) 48 Young modulu in thickne direction (GPa) 33 In-ane hear modulu G (GPa) 9 Through-thickne hear modulu G (GPa) 9 3,G 3 In-ane Poion ratio. Through-thickne Poion ratio 3,3. Longitudinal tenile trength X (MPa) T 55 Longitudinal compreive trength X (MPa) 5 Tranvere tenile trength Tranvere compreive trength Tranvere hear trength Longitudinal hear trength C Y (MPa) T 55 Y (MPa) 5 C S (MPa) T S (MPa) The Hahin damage criterion baed on work of Hahin and Rotem and Hahin [44, 45]. Thi criterion i unlike other criteria like Tai-Hill and Tai-Wu[46, 47]. Thoe criteria purpoed an equation to predict damage initiation. The Hahin damage preent four failure mode with four correponding indexe (a) t c breakage of fibre from the tenion F f, (b) buckle of fibre from the compreion F f, (c) crack of the t c matrix from the tenion F m and (d) cruh of the matrix from the compreion F m. There i four equation that apied to thoe failure mode repectively: L 6

7 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 t F.and f (9) St S c F.and f () Sc t c F.and m 3 () S S 3 m 3 () S 3 S S c S c S c F.and, and are apied tree while i a coefficient of the hear tre which contributed in fibre breakage by a tenion criterion. In the Abaqu, the criterion of Hahin could be imemented in a conjunction with a damage evolution law. The law baed on a pecification of four fracture energyvalue G. The value correponded to the material degradation in each mode. The value contituent in an imementation of the Hahin-baed and analyed with the damage evolution in the Abaqu. The damage variable for fibre d f, matrix d m and hear d were aeed by thi expreion [48]: f eq eq eq d f eq eq eq (3) f eq i an equivalent of a diacement in an F when the tre reached to zero in a trediacement while eq i an equivalent of a diacement when the damage initiated. eq i an equivalent of a diacement in F for the given apied train [48]. 4. Reult and Dicuion The damaged area of the laminate i depended on a crohead diacement of the quai-tatic loading. The crohead diacement and the contituent material, the 4- aluminium alloy and carbon fibre reinforced polymer were in the preent cae. The prior to teting, the type of rein ued and metal anding were invetigated. The thermoet epoxy wa ued a a matrix to laminate the carbon fibre with the aluminium alloy. The andpaper with grit 8 wa apied on the aluminium alloy a to increae the bonding between the heet metal and matrix. From the graph, it howed that the trending of failure on the fibre metal laminate became decreaed when the crohead diacement wa increaed from mm/min to mm/min. 7

8 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 Load (kn) mm/min 5 mm/min mm/min 5 mm/min mm/min Central defelction( mm) Figure 3. Graph of load againt central deflection in Aluminium/CFRP FML The failure proce of the quai-tatic indentation on the FML wa invetigated by examining the front urface and rear-urface of the impact damaged ame. The initial fracture onto the / FML by mm/min crohead diacement. The experiment wa handle by uing Intron 3369 Univeral Teting Machine. The mm/min impact hown in a Figure 4a. The damaged area ha been taken through an indentation tage by the indenter at a top urface of the aluminium alloy. At the econd tage, there wa a localize crack on the matrix. The failure on the matrix becaue of the preparation of layup proce. The laminate tart to bend becaue of the maximum load that acted on it and the laminate ha a maximum bending. After that, there wa a fibre breakage becaue of the maximum bending of the loading and the tiffne of the fibre. Then, there wa an indentation on the bottom y, aluminium alloy. The perforation on the laminate happened at the third tage of failure. The paage of the indenter through the target and produce a clean hole with a diameter that imilar to the indenter. From the graph, the perforation involved a local ductility. The higher crohead diacement reulted in a decreae of compoite tructure degradation. Beide that, there wa a number of tranvere crack which increae the delamination of the laminate epecially at the middle area of the pecimen. The matrix crack alo caued delamination of the laminate. When the teting wa carried out with the lowet crohead diacement of quai-tatic loading it reulted in an extenive delamination at the middle part and bottom y. When the crohead diacement increaed, the deformation on the fibre metal laminate happened at the ame time. The matrix of the laminate damaged caued by impact and the connection between matrix-fibre became degradation. The epoxy rein i brittle and ha low reitance to the crack propagation. The crack happened at a high tranvere hearing tre which connected with the contact force. The bending crack occurred eaily if the volume of the matrix i higher than the volume of the fibre. In the experimental work, the range of crohead diacement - mm/min involved delamination layer, failure of the fibre, atic deformation and cracking of the aluminium layer. The energy lot 8

9 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 defined a will be decreaing when the impact crohead diacement wa increaed. i energy aborption factor. The lot energy would contituent the energy which ued to rebound the impactor. Beide that, the energy alo ued a to overcome the friction from the indenter and during the impact, a ound would be produced. The ound igned for the failure of the fibre and cracking of the aluminium alloy. The deformation behavior of the top urface have been hown in the Fig 4 repectively. The increaing of impact crohead diacement caued the impact energy localized around the impacted area which leaded to fracture and penetration of that area for FML panel with ain weave compoite fibre. (a) (b) (c) (d) (e) Figure 4. The viual reult FML penetration baed on different crohead diacement. The / FML model baed on aluminium and carbon fibre wa predicted through a finite element method; Abaqu. The numerical analyi wa done a to predict the failure behavior of the FML model under the dynamic impact loading. The model wa analyed by different velocitie. The failure mechanim of the model wa recorded. The F model became ucceful when at the perforation tage of the impact event. The failure area of the FML increaed becaue the impact velocity ha been apied increaingly. The FML exhibited and appeared with little atic deformation at the impact location. The atic deformation wa in aluminium and there wa a fracture on the compoite y. The reult clearly howed that the different impact velocity reulted in the flexural tiffne. The number of element for indenter i 345 while for the FML conited with 475 number of element. 9

10 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 (a) (b) FML: Indenter: Symmetry/Antiymmetry/ncater Diacement/Rotation ncater (U=U=U3=UR=UR=UR3=) Figure 5. (a) Mehing and boundary condition of FML (b) imulation of FML. Load (kn) xp F Central defelction (mm) Figure 6. Validation graph between experimental and finite analyi data. 5. Concluion The experimental invetigation wa done and the finite element analyi of quai-tatic tet on / FML wa preented in detail. The bonding at interlayer of the FML wa improved by metal anding method. The impact area increaed a the crohead diacement wa increaed from to mm/min. The failure behaviour of the aluminium/cfrp laminate compoite wa modelled and analyed uing finite element method, Abaqu/xicit. A expected, the urface area from the impact loading increaed when

11 4th International Conference on Mechanical ngineering Reearch (ICMR7) IOP Conf. Serie: Material Science and ngineering (7) 46 doi:.88/ x/57//46 the impact velocity alo ha been increaed. The finite element analyi wa uccefully predicted in load-diacement for the hybrid laminate and identifying the failure behaviour of the hybrid laminate. The prediction offered by the numerical model wa found that the validation ha good agreement with the experimental data which provide an appropriate value for the initial imperfection value wa ran through the analyi. The analyi wa baed on the impact failure repone of the fibre metal laminate by the quai-tatic loading. According to the fact that the numerical model wa aumed a a perfect bonding between the compoite material and heet metal ince did not include the effect of initial imperfection along the fibre metal laminate. A tudy to invetigate the failure repone of fibre metal laminate baed variou crohead diacement and found that when the FML indented by higher crohead diacement, the trength of the FML would alo increae. Further work will invetigate the behavior of the fibre metal laminate by uing Abaqu/xicit in order to capture the cruhing behavior of the laminate. On the bai reult that have been obtained through the experimental work, the behavior of the laminate were invetigated through a load-diacement curve. The high value of maximum load tipulated to high reitance of the fibre metal laminate to the quai-tatic indentation. The relationhip between indentation crohead diacement and the laminate thickne have been confirmed by the experimental reearch. The value of the maximum load that ha been recorded by the aluminium/cfrp wa about 4. kn. The evaluation on the damaged fibre metal laminate it i poible to compare the damaged urface area by an experimental reearch. It ha been found that, increaing of crohead diacement would increae the damage urface area. A detail obervation on the cro-ection of the fibre metal laminate were revealed by the preence of matrix cracking and delamination between compoite layer a well a delamination at metal-compoite interface. The laminate thickne wa lead to degradation degree. The lower thickne of laminate would have greater deformation and lower metal layer cracking. A laminate increaed with thickne wa accompanied by decreaing in degree of laminate deformation and occurring delamination between the individual compoite layer and delamination on metal-compoite interface. Acknowledgment The author are grateful to the Minitry of Higher ducation and Univeriti Malayia Pahang for funding thi reearch RDU 638 Reference [] Vlot A, Krull M 997 J. Phy. IV 7 C3-45-C3-5. [] Chai G B, Manikandan P 4 Compoite Structure [3] Nakatani H, Koaka T, Oaka K, Sawada Y Compoite Part A: Apied Science and Manufacturing [4] Sarlin, Apotol M, Lindroo M, Kuokkala V-T, Vuorinen J, Lepitö T, et al. 4 Compo. Struct [5] Zhang Z, Wang W, Ran C, Benedictu R 6 Procedia Structural Integrity [6] Pärnänen T, Kanerva M, Sarlin, Saarela O 5 Compoite Structure [7] Sadighi M, Alderlieten R C, Benedictu R International Journal of Impact ngineering [8] Bieniaś J, Jakubczak P, Surowka B, Dragan K 5 Archive of Civil and Mechanical ngineering [9] Hu Y, Zheng X, Wang D, Zhang Z, Xie Y, Yao Z 5 J. Mater. Proce. Technol

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