Brittle materials at high-loading rates: an open area of research

Abstract

Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

Rate-Dependent Scaling of Dynamic Tensile Strength of Quasibrittle Structures

“…According to Eq. (3), we have n b ¼ (D/l 0s ) 2 . Therefore, the statistics of the nominal strength of the specimen is modeled by a plastic bundle, and the scaling of the standard deviation is given by Eq.…”

“…Understanding the influence of loading rate on the structural strength plays an important role in the design of engineering structures against impact loading. Over the years, brittle heterogeneous materials, such as ceramics and composites, have extensively been used in many protective technologies including human and vehicle armors [1,2]. These engineering applications have stimulated substantial advances in computational modeling of dynamic fracture of brittle and quasibrittle materials.…”

Dynamic characterization of adobe in compression: the effect of fibre fraction in soil matrix

“…The mechanical properties in tension of steel adhering to the matrix increase the strength and the toughness of the material [2]. As a result, SFRC is effective on resisting high loading rate impacts with lower penetration depth or residual velocity values in case of ballistic conflicts [3]. Actually, mixing matrices with fibers is not a new practice but starts with the use of adobe in the history of construction materials, a masonry of raw earthen bricks and mud mortar [4].…”

On the Strain Rate Sensitivity of Coarse-Grained Rock: A Mesoscopic Numerical Study

“…Rocks are strongly strain rate sensitive materials, which makes their behavior under dynamic loading challenging from the geotechnical engineering point of view (Forquin 2017;Li et al 2017Li et al , 2018Qian et al 2009). When the strain rate increases, the strain rate sensitivity of rock is realized as an apparent increase in both tensile and compressive strengths accompanied with a transition from single crackto-multiple crack/fragmentation failure mode (Denoual and Hild 2000;Xia and Yao 2015;Zhang and Zhao 2014;Zhang et al 1999).…”