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. 2023 Feb 17;23(4):2273.
doi: 10.3390/s23042273.

Numerical Design of a Thread-Optimized Gripping System for Lap Joint Testing in a Split Hopkinson Apparatus

Bernardo S Moreira  1 , Paulo D P Nunes  2 , Carlos M da Silva  1 , António Francisco G Tenreiro  2 , António M Lopes  1   2 , Ricardo J C Carbas  1   2 , Eduardo A S Marques  1   2 , Marco P L Parente  1   2 , Lucas F M da Silva  1   2
Affiliations

Numerical Design of a Thread-Optimized Gripping System for Lap Joint Testing in a Split Hopkinson Apparatus

Bernardo S Moreira et al. Sensors (Basel). .

Abstract

Currently, few experimental methods exist that enable the mechanical characterization of adhesives under high strain rates. One such method is the Split Hopkinson Bar (SHB) test. The mechanical characterization of adhesives is performed using different specimen configurations, such as Single Lap Joint (SLJ) specimens. A gripping system, attached to the bars through threading, was conceived to enable the testing of SLJs. An optimization study for selecting the best thread was performed, analyzing the thread type, the nominal diameter, and the thread pitch. Afterwards, the gripping system geometry was numerically evaluated. The optimal threaded connection for the specimen consists of a trapezoidal thread with a 14 mm diameter and a 2 mm thread pitch. To validate the gripping system, the load-displacement (P-δ) curve of an SLJ, which was simulated as if it were tested on the SHB apparatus, was compared with an analogous curve from a validated drop-weight test numerical model.

Keywords: Single Lap Joint (SLJ); Split Hopkinson Bar (SHB); adhesive; gripping system; high strain rate; impact; thread optimization.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Model of gripping system with a detailed view of the cavity (dimensions in mm).
Figure 2
Figure 2
Three-dimensional model of the bar apparatus with the calibration specimen.
Figure 3
Figure 3
Incident, transmission, and reflected waves from the three-dimensional simulation results.
Figure 4
Figure 4
Thread stress distribution in the three-dimensional model.
Figure 5
Figure 5
Mesh details for the asymmetric model with a triangular thread shape.
Figure 6
Figure 6
Schematic representation of the model with initial and boundary conditions.
Figure 7
Figure 7
Simulation results from axisymmetric model. (a) Stress waves from the axisymmetric simulations. (b) Maximum stress in thread (stress in MPa).
Figure 8
Figure 8
Incident, transmitted, and reflected waves for different thread types.
Figure 9
Figure 9
Maximum stress (in MPa) in the thread connection for different thread shapes (female thread). (a) Triangular thread. (b) Trapezoidal thread. (c) Quadrangular thread.
Figure 10
Figure 10
Maximum stress (in MPa) in the thread connection for different thread shapes (male thread). (a) Triangular thread. (b) Trapezoidal thread. (c) Quadrangular thread.
Figure 11
Figure 11
Incident, transmitted, and reflected waves for different thread diameters.
Figure 12
Figure 12
Incident, transmitted, and reflected waves for different thread pitch sizes.
Figure 13
Figure 13
Maximum stress in the neighborhood of the bar edge, as indicated in the legend.
Figure 14
Figure 14
Numerical model of the SHB apparatus with the designed gripping system and a single lap joint specimen (with specimen dimensions in mm) for validation.
Figure 15
Figure 15
Numerical model of a single lap joint specimen being tested in a drop-weight apparatus.
Figure 16
Figure 16
Load–displacement curve, P−δ, for the DP 8005 lap joint.
Figure 17
Figure 17
Incident, reflected, and transmitted strain waves from the SHB validation model.
Figure 18
Figure 18
Load–displacement curves (P−δ) of the SLJ with the crash-resistant adhesive for the SHB and the drop-weight test validation models.
Figure 19
Figure 19
Specimen strain rate estimated by the bar strains with the SHB model.
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References

    1. da Silva L.F.M., Öchsner A., Adams R.D. Handbook of Adhesion Technology. 2nd ed. Springer International Publishing AG; New York, NY, USA: 2018.
    1. Machado J.J.M., Marques E.A.S., da Silva L.F.M. Adhesives and adhesive joints under impact loadings: An overview. J. Adhes. 2018;94:421–452. doi: 10.1080/00218464.2017.1282349. - DOI
    1. ASTM International; West Conshohocken, PA, USA: 2003. Standard Test Method for Impact Strength of Adhesive Bonds. - DOI
    1. ISO; Geneva, Switzerland: 1993. Dhesives—Determination of Dynamic Resistance to Cleavage of High-Strength Adhesive Bonds under Impact Wedge Conditions—Wedge Impact Method.
    1. Boland A.J., Lopes A.M., da Silva C.M.S.M., Tenreiro A.F.G., da Silva L.F.M., Nunes D.P., Marques E.A.S., Carbas R.J.C. Development of a Split Hopkinson Pressure Bar Machine for High Strain Rate Testing of Bonded Joints. J. Test. Eval. 2022;50:20200677. doi: 10.1520/JTE20200677. - DOI