ABSTRAKPenelitian ini bertujuan untuk menyelidiki pengaruh ketebalan adhesif epoksi/serbukaluminium dan surface treatment terhadap kekuatan geser, serta mengamati karakteristikpenampang patah single lap joint plat aluminium/CFRP. Identifikasi karakteristik penampangpatah 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 dibuatdengan 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 serbukaluminium (12,5% dari berat total adhesif). Formula adhesif dicampur menggunakan mixingmachine selama 6 menit pada kecepatan 60 rpm. Adhesif epoksi/serbuk aluminum dilaminasipada kedua adherend. Waktu mulai penekanan adalah 20 menit, kemudian area sambunganditekan pada tekanan 9 bar selama 6 jam. Variasi yang digunakan adalah ketebalan adhesifepoksi/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. Sebelumpengujian geser, semua spesimen diberikan perlakuan post cure dengan suhu 1000C selama 15menit.Hasil penelitian menunjukkan bahwa: (1) peningkatan ketebalan adhesif dari 0,2 mm ke 0,4mm menyebabkan peningkatan kekuatan geser single lap joint plat Al 2024/CFRP. Namunketebalan adhesif di atas 0,4 mm menyebabkan penurunan kekuatan geser secara signifikan.Perilaku ini disebabkan oleh sifat adhesif epoksi/serbuk alumunim yang brittle; (2) surfacetreatment, acetone, menghasilkan kekuatan geser terbaik dengan nilai 9,31 N/mm2. Acetonemenyebabkan 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 kegagalanABSTRACTThe objectives of this study are to investigate the effect of the thickness epoxy/aluminumpowder adhesive and surface treatment on the shear strength, and then to observe the failuretype characteristics of single lap joint aluminum plate/CFRP. Identification a failure typecharacteristics 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 byhand lay-up method with 30% (w/w) woven roving carbon fiber and 70% (w/w) bisphenolicresin. Adhesive was contained by epoxy A and B (1:1), with the addition of aluminum finepowder filler (12.5% of the total weight of the adhesive). The adhesive formula was mixed bymixing machine for 6 minutes at 60 rpm. Epoxy/aluminum fine powder adhesive was laminatedon both of the adherend. The start time to pressure for the joint process was 20 minutes, and thenthe joint was pressed at 9 bar for 6 hours. The variables in this study were thicknessepoxy/aluminum fine powder adhesive (i.e. 0.2 mm; 0.4 mm; 0.6 mm; 0.8 mm; 1 mm) and surfacetreatment (i.e. acetone, chromate sulfuric acid, caustic etch, tucker's reagent) on the Al 2024plat. Before shear testing, all specimens were given post curing treatment at 100oC for 15minutes.The results of this study are as follows: (1) the increase of thickness epoxy/aluminum finepowder adhesive from 0.2 mm to 0.4 mm can improve the shear strength of single lap joint Al2024 plate/CFRP. Whereas the adhesive thickness is more than 0.4 mm, the shear strengthdecreases significantly. It is caused by the adhesive properties of epoxy/aluminum fine powderwhich is brittle; (2) Acetone gives maximum shear strength at 9.31 N/mm2. Acetone affectsdistribution 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