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