Experimental Investigation and Model Validation of the Shear Strength of Hybrid Interfaces up to Complete Failure

Abstract

The paper experimentally investigates hybrid interfaces pressure-reinforced and bonded with anaerobic adhesive. While their static strength has been deeply investigated, their behavior up to complete failure lacks of a constitutive model. This work aims to assess the applicability of a simple model involving a cohesive law and a pure friction law, in order to describe the interface behavior up to complete failure under different contact pressure levels. A systematic experimental campaign investigates the shear strength of cylindrical specimens butt-bonded and pressure reinforced over an annular surface. The tests involve two anaerobic adhesives and four pressure levels. The experimental torque-rotation curves confirm that the strain energy up to complete failure is given by a cohesive term and a pure friction term, both of them linearly dependent upon the contact pressure.

Predicting the Macroscopic Shear Strength of Tightened-Bonded Joints from the Intrinsic High-Pressure Properties of Anaerobic Adhesives

“…The comparison between the micromechanical model prediction (Equation (1), according to the coefficients in Table 3) and the literature data shows good agreement, specifically with the data from Dragoni and Mauri [2]. With regard to Loctite 243, Figure 7 highlights that the micromechanical model prediction has a slightly lower slope than the data from Dragoni and Mauri [2], while a more significant difference appears between the micromechanical model prediction and the data from Castagnetti and Dragoni [40,42]. Specifically, the micromechanical model tends to overestimate the response at low contact pressure and underestimate it at high contact pressure.…”

“…More recent experimental and numerical investigations by Castagnetti et al [39][40][41][42] preliminarily confirmed the applicability of this model.…”

“…Table 3 presents the coefficients of the linear regression lines in Figure 6, corresponding to the micromechanical model (Equation ( 2)). In order to validate the applicability of the micromechanical model in the prediction of real hybrid interfaces press-fitted and bonded with anaerobic adhesives, literature data from Dragoni and Mauri [1,2], Castagnetti and Dragoni [40,42], Ragni et al [43] were retrieved. All these experimental data refer to anaerobic adhesive in a thin film, as this usually occurs in real industrial applications.…”

“…Figures 7 and 8 show the comparison between the obtained micromechanical model predictions by means of Equation ( 1) using the parameters reported in Table 3, according to the results of the present investigations reported in Figure 6, with respect to the data from the literature for the Loctite 243 and the Loctite 648 adhesives, respectively. from Dragoni and Mauri [1,2], Castagnetti and Dragoni [40,42], Ragni et al [43] were retrieved. All these experimental data refer to anaerobic adhesive in a thin film, as this usually occurs in real industrial applications.…”

“…On the basis of a systematic experimental test plan, which measured the shear strength of the joint up to complete failure, Castagnetti et al [42,43] proposed a simple constitutive model combining a cohesive law and a pure friction law that describes the post elastic behaviour of the hybrid interface.…”