Dynamic characterization of adobe in compression: the influence of fibre fraction in soil mixtures

Adobe is one of the most ancient forms of masonry. Adobe bricks are sundried mixtures of clay, silt, sand and natural fibres locally available joined together using mud mortar. Adobe structures are largely spread in areas of the world prone to earthquakes or involved in military conflicts. Unfortunately, almost no literature concerns the dynamic...

The Ballistic Resistance of Adobe Masonry: An analytical model for impacts on mud bricks and mortar

A significant number of published papers in the field of penetration mechanics devotes attention to the study of targets made of metal and ceramic materials for protective equipment. In recent times, the progression in harshness of urban warfare is leading western governments to investing in research focused on the ballistic response of building...

Simulation of dynamic behavior of quasi-brittle materials with new rate dependent damage model

Stress-based nonlocal model, Damage, Rate dependency, Dynamic crack-branching Abstract. In concrete often complex fracture and fragmentation patterns develop when subjected to high straining loads. The proper simulation of the dynamic cracking process in concrete is crucial for good predictions of the residual bearing capacity of structures in...

A fully implicit plasticity model for the characterization of ceramics in ballistic protection

The Johnson-Holmquist-2 ceramic model is used for quasi-static indentation simulation. A modification is proposed to an associated plasticity formulation. This allows for a fully implicit solution scheme, where dilatation is used instead of the traditional explicit bulking formulation. Dilatation is shown to have an important influence on ring...

The influence of moisture on the fracture behaviour of concrete loaded in dynamic tension

Dynamic tests demonstrate an extensive rate effect on the tensile strength as well as the post-peak behaviour beyond loading rates of about 50 GPa/s. One of the possible explanations for the observed rate effects on the fracture behaviour is enhanced resistance by moisture in the pores. To study the influence of the moisture content and pore...

Modelling dynamic tensile failure of quasi-brittle materials using stress-enhanced nonlocal models

The development of realistic numerical tools to efficiently model the response of concrete structures subjected to close-in detonations and high velocity impacts has been one of the major quests in defense research. Under these loading conditions, quasi-brittle materials undergo a multitude of failure (damage) mechanisms. Dynamic tensile failure...

Experimental techniques for design of impact-resistant material (poster)

Some polymers are not only transparent and lightweight, but also impact and ballistic resistant. Designing and preparing such polymeric materials with a high impact?resistant performance is of importance to e.g. aviation, military and windscreen applications.

Damage prediction in a concrete bar due to a compression and tension pulse: A comparison of the K&C, the CSCM and the RHT material models in LS-DYNA

Advanced Finite Element codes provide the possibility to simulate high rate loading on concrete targets as ballistic impact and explosions. Although damage to RC structures due to these loadings can be simulated and detailed results can be obtained the predictions are still far from perfect. It is well known that the results strongly depend on...

Dynamic tensile resistance of concrete-split Hopkinson bar test

The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading, on meso and macro-scale concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, ductility, and, second, there are inertia forces activated which influence the...

A mesoscale modelling perspective of cracking process and fracture energy under high strain rate in tension

This paper presents a numerical modelling study on the simulation of the cracking process and fracture energy in concrete under high strain rate. To capture the stress wave effect and the damage evolution at the meso-length scale, both a homogeneous model with a millimetreresolution mesh and an explicit heterogeneous mesoscale model with random...

Drop weight impact strength of porous concretes investigated with a measurement technique using laser doppler velocimetry

Porous concrete is used in many applications that require permeability, noise absorption or thermal insulation. However, its response under dynamic loading is generally not considered. Porous concrete has a characteristic of forming multiple cracks and subsequently fracturing into small fragments when exposed to impact loading. Therefore, with...

Modelling loading and break-up of RC structure due to internal explosion of fragmenting shells

The Klotz Group (KG), an mtemational group of experts on explosion safety, investigates the debris throw hazard associated with the accidental detonation of ammunition in reinforced concrete (RC-) structures. Experiments are combined with engineering models but also with results of advanced computational modeling, which is the topie of this...

The dynamic fracture energy of concrete: Review of test methods and data comparison

Data on the dynamic fracture energy of concrete are scarce and also not consistent due to different test methods, data analyses and definitions. This paper intends to facilitate the discussion on dynamic fracture energy and start the standardization process for dynamic tensile testing. The response and failure mechanisms in statics and dynamics...

Investigation of porous concrete through macro and meso-scale testing

In designing a porous concrete, containing a high volume of air pores, the effects of its mesoscale phases on its macro level properties have to be known. For this purpose, porous concretes having different aggregate gradings and cement paste compositions were investigated through macro-scale strength tests. The tests showed that aggregate...