Abstrak |
: |
ABSTRAK Penelitian ini bertujuan untuk menyelidiki pengaruh ketebalan adhesif epoksi/serbuk aluminium dan surface treatment terhadap kekuatan geser, serta mengamati karakteristik penampang patah single lap joint plat aluminium/CFRP. Identifikasi karakteristik penampang patah dapat menjelaskan kekuatan geser single lap joint plat aluminium/CFRP. Plat Al 2024, CFRP, resin bisphenolic, promotor P-EX, katalis MEKPO, adhesif epoksi, serbuk aluminium, dan larutan kimia merupakan bahan dalam penelitian ini. CFRP dibuat dengan proses hand lay-up dengan 30% (w/w) serat karbon dan 70% (w/w) resin bisphenolic. Kandungan adhesif terdiri dari epoksi A dan B (1:1), dengan penambahan filler serbuk aluminium (12,5% dari berat total adhesif). Formula adhesif dicampur menggunakan mixing machine selama 6 menit pada kecepatan 60 rpm. Adhesif epoksi/serbuk aluminum dilaminasi pada kedua adherend. Waktu mulai penekanan adalah 20 menit, kemudian area sambungan ditekan pada tekanan 9 bar selama 6 jam. Variasi yang digunakan adalah ketebalan adhesif epoksi/serbuk aluminium (0,2 mm ; 0,4 mm ; 0,6 mm ; 0,8 mm ; 1 mm) dan surface treatment (acetone, chromate sulphuric acid, caustic etch, tucker’s reagent) pada plat Al 2024. Sebelum pengujian geser, semua spesimen diberikan perlakuan post cure dengan suhu 1000C selama 15 menit. Hasil penelitian menunjukkan bahwa: (1) peningkatan ketebalan adhesif dari 0,2 mm ke 0,4 mm menyebabkan peningkatan kekuatan geser single lap joint plat Al 2024/CFRP. Namun ketebalan adhesif di atas 0,4 mm menyebabkan penurunan kekuatan geser secara signifikan. Perilaku ini disebabkan oleh sifat adhesif epoksi/serbuk alumunim yang brittle; (2) surface treatment, acetone, menghasilkan kekuatan geser terbaik dengan nilai 9,31 N/mm2. Acetone menyebabkan lamination (pembasahan) adhesif terhadap permukaan plat Al 2024 lebih merata; (3) jenis kegagalan sambungan, mixed failure (light-fiber-tear failure dan cohesive failure), mengindikasikan kekuatan geser tertinggi. Kata kunci : CFRP, ketebalan adhesif, surface treatment, kekuatan geser, jenis kegagalan ABSTRACT The objectives of this study are to investigate the effect of the thickness epoxy/aluminum powder adhesive and surface treatment on the shear strength, and then to observe the failure type characteristics of single lap joint aluminum plate/CFRP. Identification a failure type characteristics can explain the shear strength of single lap joint aluminum plate/CFRP. Al 2024 plate, CFRP, bisphenolic resin, P-EX promoter, MEKPO catalyst, epoxy adhesive, aluminum fine powder, and a chemical solution were used in this study. CFRP was made by hand lay-up method with 30% (w/w) woven roving carbon fiber and 70% (w/w) bisphenolic resin. Adhesive was contained by epoxy A and B (1:1), with the addition of aluminum fine powder filler (12.5% of the total weight of the adhesive). The adhesive formula was mixed by mixing machine for 6 minutes at 60 rpm. Epoxy/aluminum fine powder adhesive was laminated on both of the adherend. The start time to pressure for the joint process was 20 minutes, and then the joint was pressed at 9 bar for 6 hours. The variables in this study were thickness epoxy/aluminum fine powder adhesive (i.e. 0.2 mm; 0.4 mm; 0.6 mm; 0.8 mm; 1 mm) and surface treatment (i.e. acetone, chromate sulfuric acid, caustic etch, tucker's reagent) on the Al 2024 plat. Before shear testing, all specimens were given post curing treatment at 100oC for 15 minutes. The results of this study are as follows: (1) the increase of thickness epoxy/aluminum fine powder adhesive from 0.2 mm to 0.4 mm can improve the shear strength of single lap joint Al 2024 plate/CFRP. Whereas the adhesive thickness is more than 0.4 mm, the shear strength decreases significantly. It is caused by the adhesive properties of epoxy/aluminum fine powder which is brittle; (2) Acetone gives maximum shear strength at 9.31 N/mm2. Acetone affects distribution of adhesive laminate better than the others; (3) The type of failure, mixed failure (light fiber tear failure and cohesive failure), indicates the highest shear strength. Keywords : CFRP, adhesive thickness, surface treatment, shear strength, failure type |