PSI - Issue 83

R.J.B. Rocha et al. / Procedia Structural Integrity 83 (2026) 179–186

184

frequently initiated at the geometric discontinuities (step corners), producing mixed AL/AD modes at small L O . AD failures increased markedly with L O , becoming dominant at 20 mm for most combinations. The SJ profile reduced peel stresses when compared to SLJ but introduced local stress concentrations that limited overall performance in comparison with SLJ. The 2015 promoted cleaner, more brittle AL or AD failures, while the 7752 consistently allowed greater plastic deformation in the adhesive layer, leading to more ductile AL fractures. PLA adherends exhibited the lowest incidence of AD failure due to their higher stiffness and strength, which allows the adhesive capacity to be fully exploited. PETG and ABS adherends were more prone to adherend cracking (i.e., AD failure) at larger L O . Increasing L O triggered a desirable transition from adhesive-controlled to adherend-controlled failure in all geometries, indicating that the joints can be sized to fully utilize the strength of the AM polymers. Fig. 4 compares the experimental and numerical load-displacement ( P -  ) curves from SLJ and SJ manufactured with ABS adherends and bonded with the 2015 for L O =5 and 20 mm. A good correlation between both data was found. All joints exhibit similar stiffness for L O =5 mm, although SJ endure higher P m and elongation at break. Increasing L O to 20 mm reveals that its effect in P m for SJ is negligible (5.7%), whereas for SLJ a P m increase of 85.2% was found. Fig. 5 compares the experimental and numerical P -  curves extracted from SLJ and SJ with ABS adherends and bonded with the 7752 for L O =5 and 20 mm. Similar behavior to the 2015 was found, i.e., comparable stiffness for L O =5 mm, with higher P m for the SJ (12.2%). For L O =20 mm, the SJ maintains the P m and the stiffness, while SLJ P m increases by 84.2%. Failure consistently occurred upon reaching P m , irrespective of the specific conditions. 3.2. Joint strength

120

120

100

100

80

80

60

60

P [N]

P [N]

40

40

20

20

0

0

0

2

4

6

8

10

12

14

16

0

5

10

15

20

25

 [mm]

 [mm]

SLJ_SP1

SLJ_SP2

SLJ_SP3

SLJ_Num STEP_Num

SLJ_SP1

SLJ_SP2

SLJ_SP3

SLJ_Num STEP_Num

a)

b)

STEP_SP1

STEP_SP2

STEP_SP3

STEP_SP1

STEP_SP2

STEP_SP3

Fig. 4. Experimental and numerical P - δ curves obtained for the SLJ and SJ with the 2015: a) ABS with L O =5 mm and b) ABS with L O =20mm.

100 120

120

100

0 20 40 60 80

80

60

P [N]

P [N]

40

20

0

0

5

10

15

0

5

10

15

20

25

 [mm]

 [mm]

SLJ_SP1 SLJ_Num STEP_SP1 STEP_SP2 STEP_SP3 SEP_Num SLJ_SP2 SLJ_SP3

SLJ_SP1

SLJ_SP2

SLJ_SP3

SLJ_Num STEP_Num

a)

b)

STEP_SP1

STEP_SP2

STEP_SP3

Fig. 5. Experimental and numerical P - δ curves obtained for the SLJ and SJ with the 7752: a) ABS with L O =5 mm and b) ABS with L O =20mm.

Fig. 6 compares the experimental and numerical P m for SLJ manufactured with PLA (a), ABS (b), and PETG (c) adherends. The highest P m was found for PLA adherends bonded with the 7752 and L O =20 mm (160.8±4.7 N). P m improvement from L O =5 mm to 10 mm is notorious with PLA adherends (111.5%), while from L O =10 to 20 mm the difference is smaller (21.6%). Other adherends follow the same trend. The more flexible 7752 results in lower P m but enables larger  before failure, which is especially advantageous for the ductile ABS and PETG adherends.