Development of a Split Hopkinson Pressure Bar Machine for High Strain Rate Testing of Bonded Joints

Abstract

The design of adhesively bonded connections for structural applications has recently become a major field of research, with extensive applications in the automotive and aerospace industries. In these structures, bonded joints are often subjected to important static and dynamic loads, which require careful geometrical dimensioning and material selection. The performance analysis of adhesive joints under these conditions is often made with numerical modeling and supported by experimental studies that can correctly characterize their mechanical behavior. To obtain this characterization under impact conditions, it is critical to employ equipment suitable for impact testing of adhesives and adhesive joints. For this reason, an innovative Split Hopkinson Pressure Bar machine was designed. This machine includes a pneumatic actuator capable to operating up to 30 m/s in both directions, and an innovative lever-based braking system, capable of stopping the actuator for both tensile and compression tests. The tensile and compression pressure bar setups, as well as the machine support and its characteristics, are also described.

An update on the development of techniques for the determination and modelling of the impact behaviour of adhesives and bonded structures used in the automotive sector

“…6 Because the AJPU is involved in a number of academic and industry research initiatives in this field, it has applied its experience in testing these materials to the development of an innovative and cutting-edge SHPB testing system that is specifically tailored to meet the needs of adhesive and adhesive joint testing. 7 Figure 3 depicts a schematic view of this equipment as designed.…”

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

“…However, these strain rates are still considerably lower when compared to other experimental procedures, such as the Split Hopkinson Bar (SHB) test. Consequently, the aim of this paper is to develop tools and procedures to test adhesive joints using an SHB apparatus that, despite not following any standardized procedure, can attain high strain rates [ 5 , 6 , 7 ].…”

“…In this manner, the strain values at the bars are obtained, and, indirectly, the strain and stress levels acting on the specimen can be computed. This acquisition system usually contains other components, such as a striker speed acquisition device [ 5 , 6 , 7 ]. The test can also be complemented with other technologies to analyze the behavior of the specimen, namely a Digital Image Correlation (DIC) equipment [ 7 , 8 , 9 ].…”

“…Various types of SHB apparatuses exist that are suitable for different states of loading, such as compressive [ 7 , 10 , 11 ], tensile [ 5 , 6 , 7 , 12 ], torsional [ 7 , 13 ], or triaxial loads [ 7 , 14 ], amongst others. While the compressive SHB setup is more commonly used [ 6 , 7 ], this paper focuses on a tensile SHB machine, which is very similar to the typical compressive SHB apparatus.…”