An experimental investigation on the failure loads of the mono and bi-adhesive joints

Figures & data

Table 1. Mechanical properties of adhesives.[2, 24]

		Araldite 2015	Araldite AV138 M
Elasticity modulus	MPa	1850 ± 0.21	4590 ± 0.81
Poisson’s ratio		0.33	0.35
Tensile strength	MPa	21.63 ± 1.61	41.01 ± 7.28
Tensile yield strength	MPa	12.63 ± 0.61	36.49 ± 2.47
Shear modulus	MPa	560 ± 0.21	1560 ± 0.01
Shear yield strength	MPa	14.6 ± 1.3	25.1 ± 0.33
Shear strength	MPa	17.9 ± 1.8	30.2 ± 0.4
Shear failure strain	%	43.9 ± 3.4	7.8 ± 0.7

Table 2. Chemical composition of DIN C75 steel (Wt.%).

C	Si	Mn	P	S	Mg	Cr	Ni	Mo	Cu	Al
0.718	0.337	0.783	0.011	0.002	0.0005	0.316	0.037	0.022	0.026	0.007
Ti	V	Nb	W	Co	B	Sn	Pb
0.003	<0.001	0.007	0.009	0.005	<0.0001	0.002	0.005

Table 3. Adherend mechanical properties.[2]

Modulus of elasticity (MPa)	Poisson’s ratio	Tensile strength (MPa)	Tensile yield strength (MPa)
198,300	0.29	1413	1260

Figure 1. Dimensions and geometries of mono and bi-adhesive joints.

Figure 2. Predicted overlap length corresponding to adherend and adhesive yielding.

Figure 3. Acetone cleaned and sandblasted-adherend surfaces.

Figure 4. Mono and bi-adhesive joint manufacturing mold.

Table 4. Cure temperature and time of the mono and bi-adhesive joints.[2]

	Adhesive	Temperature (°C)	Time (min.)
Mono	AV138	80	15
	DP-8005	80	60
	Araldite 2015	60	60
Bi-adhesive	AV138 + DP-8005	80	60
	AV138 + 2015	60	60

Figure 5. Curing periods for the adhesives.

Figure 6. Single lap joint specimens.

Figure 7. Tensile testing setup.

Figure 8. Cohesive failure of bi-adhesive bondline.

Figure 9. Fracture surfaces of mono and bi-adhesive bondlines.

Figure 10. Crack propagation of the joint with mono AV138 adhesive (see Figure 9(a)).

Figure 11. Load–displacement curves of mono-adhesive joints.

Figure 12. Load–displacement curves of mono and bi-adhesive joints (AV138 + 2015).

Figure 13. Load–displacement curves of mono and bi-adhesive joints (AV138 + DP-8005).

Table 5. Experimental and predicted failure loads.

Bondline	Adhesives	Bondline configuration	Failure loads (kN)
			Experimental	Predicted
				Volk.	G.Y	Volk. + G.Y
Mono	AV138	Stiff adhesive only	14.51	12.00	31.37
	Araldite 2015	Ductile adhesive only	20.76	11.37	18.25
	DP-8005	Flexible adhesive only	10.70	7.78	6.62
Bi-adhesive	AV138 + DP-8005	ξ = 0.5 (12-24-12)	20.65			14.09
	AV138 + 2015	ξ = 0.3 (09-30-09)	27.69			18.06
		ξ = 0.5 (12-24-12)	29.17			19.67
		ξ = 0.7 (14-20-14)	25.30			20.45

Note: Volk. from Equation (8), G.Y from Equation (10) and Volk. + G.Y from Equation (11).

Table 6. Experimental and predicted shear strengths.

Bondline	Adhesives	Bondline configuration	Experimental	Predicted
			Avg. shear strength (MPa)	Shear strength capacity (MPa)
Mono	AV138	Stiff adhesive only	11.61	30.20
	Araldite 2015	Ductile adhesive only	16.61	17.90
	DP-8005	Flexible adhesive only	8.56	8.40
Bi-adhesive	AV138 + DP-8005	ξ = 0.5 (12-24-12)	17.21	19.30
	AV138 + 2015	ξ = 0.3 (09-30-09)	23.08	25.59
		ξ = 0.5 (12-24-12)	24.31	24.05
		ξ = 0.7 (14-20-14)	21.10	23.03

Note: Avg. = Average.

Figure 14. Experimental average shear stress and predicted shear strength of mono and bi-adhesive joints.

da Silva LFM, Lopes MJCQ. Joint strength optimization by the mixed-adhesive technique. Int J Adhes Adhes. 2009;29:509–514.10.1016/j.ijadhadh.2008.09.009

 Web of Science ®Google Scholar