Abstract
The MultiMat experiment was successfully conducted at CERN's HiRadMat facility, aiming to test novel high-performance materials for use in beam intercepting devices, allowing the derivation and validation of material constitutive models. This article provides an analysis of results for two materials tested in the experiment, namely Silicon Carbide and Titanium Zirconium Molybdenum, with the aim of benchmarking the material constitutive models currently available in literature with experimental results. The material models were implemented in numerical simulations, successfully modelling dynamic longitudinal and flexural phenomena. The article further studies the modelling of the complex boundary conditions present in the experiment, the internal damping characteristics of the materials, and the failure of certain specimens. The strength and failure models proved adequate to model a number of experimental scenarios tested, but require further study to describe the material behaviour at the high strain rates and temperatures induced by accidental particle beam impacts. A post-irradiation examination of the tested specimens was also performed to study the nature of failure in the specimens, and is to be coupled with quasi-static and high strain rate tests for both materials, allowing for the validation of the currently available models and the description of material behaviour across a wide range of strain rates and temperatures.
Highlights
In the upcoming high luminosity upgrade of the LHC (HL-LHC) (Apollinari et al, 2017), the energy stored in the circulating beams will increase from 360 to 680 MJ, while for the proposed Future Circular Collider (FCC) (Benedikt and Zimmerman, 2016) the beam energy is projected to reach up to 8500 MJ
This paper focuses on the results for two materials, Silicon Carbide (SiC) and Titanium Zirconium Molybdenum (TZM), two materials which, as detailed, exhibited failure during the experiment
It is interesting to note that in the case of TZM, experimental measurements on the second specimen yielded a longitudinal frequency of 14.5 kHz, indicating that the specimen had failed upon beam impact or in a previous shot, as will be discussed further on in the section detailing the modelling of specimen failure
Summary
In the upcoming high luminosity upgrade of the LHC (HL-LHC) (Apollinari et al, 2017), the energy stored in the circulating beams will increase from 360 to 680 MJ, while for the proposed Future Circular Collider (FCC) (Benedikt and Zimmerman, 2016) the beam energy is projected to reach up to 8500 MJ. For the HL-LHC, accidental impacts due to asynchronous beam dumps or injection errors may result in thermal loads exceeding energy densities of 10 kJ/cm on the collimator jaws (Bertarelli, 2016), resulting in intense pressure waves propagating through the material, risking plasticity, fracture, and spallation of material, as well as melting and vaporization of the impacted region (Bertarelli et al, 2013) With this in mind, the materials utilised for such components and exposed to such extreme conditions require extensive experimental testing and validation in order to derive the constitutive models required to numerically simulate high energy particle beam impacts. The study further investigates the effects of boundary conditions on the flexural response, material damping in the experimental signal and its application in numerical analyses, as well as failure of the specimens and its simulation in the implicit numerical code – paving the way for more complex analyses on non-linear, anisotropic materials tested in the MultiMat experiment
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