Abstract
Mechanical characterisation of metallic materials at intermediate strain rates is essential to calibrate and validate computational models for industrial applications such as high-speed forming processes i.e. hammer forging, blanking, forming, etc. The most common devices that perform medium to high loading rate experiments are the servo-hydraulic universal testing machines and Split Hopkinson bar systems. Here we analyse the possibility of employing an in-house designed and constructed DirectImpact Drop Hammer (DIDH) for material mechanical characterisation at medium strain rates, ranging from 100 to 300 s-1. To show the suitability of the DIDH for mechanical characterisation, uniaxial compression experiments on S235JR structural steel are conducted and compared with finite element (FE) simulations performed with an elasticthermoviscoplastic material model previously calibrated with Split Hopkinson Pressure Bar (SHPB) tests.
Highlights
Introduction and motivationMetal forming in its multiple variants is massively employed in the automotive, the aeronautical or the oil and gas industries, when certain mechanical properties such as high strength and ductility are required, as they are very costeffective operations for large series production
To show the suitability of the DirectImpact Drop Hammer (DIDH) for mechanical characterisation, uniaxial compression experiments on S235JR structural steel are conducted and compared with finite element (FE) simulations performed with an elasticthermoviscoplastic material model previously calibrated with Split Hopkinson Pressure Bar (SHPB) tests
As an alternative to the SHPB systems for intermediate strain rate testing, we present an in-house designed and constructed Direct Impact Drop Hammer (DIDH)
Summary
Metal forming in its multiple variants (forging, forming, blanking, etc.) is massively employed in the automotive, the aeronautical or the oil and gas industries, when certain mechanical properties such as high strength and ductility are required, as they are very costeffective operations for large series production. These operations are performed at loading rates that exceed by far the quasi-static regime. It is essential to be able to mechanically characterise the metallic alloys heavily employed by these industrial sectors Testing within this range using universal testing machines equipped with conventional load cells becomes extremely challenging since they often have a limited stroke velocity. The steel is modelled with a Johnson-Cook-type material model calibrated using quasi-static and SHPB tests
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