Gerald Nurick

University of Cape Town | UCT · Department of Mechanical Engineering

This paper presents the key outcomes derived from a series of experiments and numerical simulations aimed at understanding how carbon fibre reinforced polymer (CFRP) retrofitted cylindrical steel tubes respond to localised external blast loads. The blast tests were conducted using a ballistic pendulum on both as-received and retrofitted tubes, empl...

This paper summarises the key findings from a series of experiments conducted to identify the response of carbon fibre reinforced polymer (CFRP) retrofitted cylindrical steel tubes to localised external blast loads. The blast tests were performed on a ballistic pendulum on bare and retrofitted tubes with various FRP retrofitting arrangements. The...

This paper reports on the results of a numerical study to simulate the response of carbon fibre reinforced polymer (CFRP) retrofitted steel plates to applied blast loads using finite element software, LS-DYNA. The results of the simulation were validated against plate response and magnitude of deformation obtained from previous experiments. The uni...

This paper concerns the mitigation of damage in aircraft luggage containers subjected to internal blast loading. It reports findings of experimental and computational work on the influence of venting on the blast response of scaled unit load devices. The internal geometry of the structure was based on a 1:6 scale version of the commonly used LD-3 u...

The results of a study on the response of a side impact beam located in a car door to impact loading is presented. The side impact beam is situated in both the front and rear side doors of a vehicle between the inner and outer shells to minimise intrusion into the passenger compartment during a collision whilst absorbing as much impact energy as po...

A Round-Robin test using split Hopkinson pressure bars (SHPBs) has been conducted by four universities: Swinburne University of Technology (SUT), Australia; University of São Paulo (USP), Brazil; University of Cape Town (UCT), South Africa; and Nanyang Technological University (NTU), Singapore. Each university had different sets of SHPBs and data a...

The response of single and double layered steel plates to localised air-blast loading was examined. Two configurations, both comprising fully clamped circular plates with a 200 mm exposed diameter, were considered: 4mm thick single and (2+2) mm double layered plates. The localised air-blast loading was applied by centrally detonating discs of PE4 p...

The Split Hopkinson Pressure Bar (SHPB) test, while widely utilised for high strain rate tests, has yet to be standardised. As an exploratory step towards developing a standard test method or protocol, a Round Robin test series has been conducted between four institutions: (i) Swinburne University of Technology, Australia (ii) University of São Pau...

The Split Hopkinson Pressure Bar (SHPB) test, while widely utilised for high strain rate tests, has yet to be standardised. As an exploratory step towards developing a standard test method or protocol, a Round Robin test series has been conducted between four institutions: (i) Swinburne University of Technology, Australia (ii) University of São Pau...

The study detailed in this manuscript focuses on the numerical and experimental testing of circular AA6061-T6 aluminum alloy extrusions subjected to cutting deformation modes under blast loading conditions, as energy dissipation devices. The experimental investigation was completed utilizing a specially designed cutter with the presence of a deflec...

This article presents an experimental and numerical investigation into the effect of charge geometry on the structural response of right circular cylinders. Thin-walled, seamless 304 stainless steel cylinders were subjected to internal blast loads that were generated by detonating bare cylindrical plastic explosive charges. Charge diameter, charge...

A series of laboratory-scale blast characterization experiments are presented to show the degree to which two alternative configurations of an instrumented ballistic pendulum can provide an ideal impulsive load. Both the total impulses and blast pressure histories were captured, the latter using a centrally mounted Hopkinson bar. Repeatable and con...

In 1989, Nurick and Martin published two review papers on the deformation of thin steel plates subjected to impulsive air-blast loading. The state of the art has progressed significantly in the following 25 years, and this review paper restricts itself to experimental studies that investigate the response of monolithic metal plates subjected to air...

The response of circular steel plates subjected to loading arising from the detonation of plastic explosive PE4 was investigated experimentally. The shape of the explosive charge, the charge dimensions and the charge mass were varied during the experiments. Cylindrical, truncated cone and the inverted truncated cone shaped explosives were detonated...

This paper presents the results of an experimental study to assess how cylindrical bars placed between an explosive source and a target plate disrupt the blast wave impinging on the target plate and its blast mitigation capabilities by means of the deflection of the structure. The blast barriers disrupting the blast wave were made from 25 mm diamet...

Anti-Vehicular Landmine or under-belly Improvised Explosive Device (IED) or even a side-attack IED are found to be one of the major threats for military vehicles and their occupants. The lower extremities of the occupants are very prone to the injuries more especially during underbelly detonation due to the spatial proximity to the rapid deforming...

This paper presents the results of an experimental and numerical investigation into the response of circular Domex-700 MC steel plates to repeated uniform blast loads. The Domex 700 steel tests plates of thickness either 2 or 3mm are mounted onto a ballistic pendulum and subjected to uniform blast load up to five times for repeated loading. In gene...

This paper present the experimental analysis of square mild steel plates subjected to blast loads in three different degrees of confinement (free air burst, fully vented and fully confined). Varying spherical masses of explosive were detonated at a constant stand-off distance from three different thickness target plates in the three different degre...

This paper presents the results of an investigation into the response of thin-walled square (60x60 mm and 76x76 mm) tubes made from mild steel filled with four different fillers; aluminium foam (Cymat 7%), two types of aluminium honeycomb and polyurethane foam to quasi-static and dynamic axial impact load. The energy absorption characteristics of t...

This paper reports on the response of cladding sandwich panels with tubular cores to uniform blast load. The panels consist of thin-walled circular tubes (38 mm in diameter) made from aluminium 6063-T6 riveted laterally between the skin plates at varying spacing arrangements to provide four different types of panels. The skin exposed to the blast l...

This paper reports the findings of a research study investigating the energy-absorbing characteristics of polymer foams reinforced with small carbon fibre reinforced epoxy tubes. Initial attention focuses on establishing the influence of tube diameter on the specific energy absorption (SEA) characteristics of the chamfered CFRP tubes. Here, it is s...

This work considers the validity of the assumption that the influence of radial displacements and bending strains can be ignored when constructing closed form analytical solutions for the large displacement response of impulsively loaded circular plates. Three successive energy based analyses are presented. The first analysis considers only membran...

Composite materials are finding use in an increasing number of structural applications as a result of their high specific strength, high specific stiffness, thermal resistance and the potential for tailoring of properties to suit specific applications. Fibre-reinforced composites, foam core sandwich panels and fibre-metal laminates (FMLs) are examp...

Anti-Vehicular Landmines (AVLs), under-belly Improvised Explosive Devices (IEDs) or even side-attack IEDs are found to be some of the major threats for military vehicles and their occupants [1]. The lower extremities of the occupants are very prone to injuries, more so during underbelly detonation of the AVL or IED as a result of their spatial prox...

This paper presents a series of experimental and numerical results on cylindrical shells subjected to external localised blast loads. The cylindrical shells are laterally loaded in the mid span using varying masses of plastic explosive (PE4) over a prescribed load diameter of 22.5 mm, 30 mm and 45 mm detonated at a stand-off distance of 13 mm. Anot...

This paper presents the results of an experimental investigation to determine the effect of the height of burial (the amount of sand beneath the buried charge) on a buried charge in terms of impulses imparted onto a rigid steel target plate (suspended from a vertical pendulum). The 40 mm rigid target plate of exposed area 400 mm x 400 mm is located...

The energy absorption of circular pultruded composite tubes subjected to axial crush load, transmitted by a small attached mass accelerated by means of an explosive load is presented in this paper. Different masses of explosive are used to provide a range of transmitted impulse and crushed distance of the pultruded composite tubes. The influence of...

Blast loads from explosion (either accidental or intentional) can be mitigated by using thick armor systems that are often heavy and significantly affect the payload of the structure. In the design of structures for blast protection, sacrificial claddings which consist of high-energy-absorbing components are often used. Sandwich-type cladding struc...

Abstract Bend tests under impact loading have traditionally been conducted using drop weight testers. However, the force readings from drop weight testers suffer from increasing oscillation (due to load frame vibration and stress wave excitation) as the impact velocity is increased. Different configurations of Hopkinson Pressure Bars (HPB) were ada...

: This article describes the experimental methodology used in overcoming the challenges of performing tests and recording results on specimens, which are suitable for such a wide range of test conditions. Uniaxial tensile tests were conducted on aluminium alloy 6082-T352 at varying temperatures and strain rates to validate testing techniques and to...

High rate delamination tests are often performed using high speed servo-hydraulic or drop-weight test frames. However, impact induced stress wave propagation in the specimen, load cell and test frame often results in oscillations in the force readings which can obscure specimen response. The Hopkinson Pressure Bar provides a means of measuring impa...

This paper presents the results of an experimental investigation on the axial splitting of thin-walled aluminium extrusions by means of blast load. Plastic explosive (PE4) was used to accelerate the circular extrusions onto a cutting die backed by a curved deflector. The apparatus was mounted on a ballistic pendulum to measure the impulse imparted...

This paper presents an experimental investigation into the response of circular Domex-700 MC steel plates to repeated uniform blast loads. The experiments are carried out on a ballistic pendulum for a 3mm thick test plate to witness up to five similar uniform blast loads. As expected, a trend of increasing permanent mid-point deflection is observed...

The effect of through-the-thickness stitching on the blast resistance of sandwich panels is investigated both experimentally and numerically. Panels based on three-dimensional woven S-glass/epoxy skins and a crosslinked PVC core were manufactured using a vacuum assisted resin infusion process. The panels were stitch-bonded using Kevlar 129 yarn, by...

The strain rate dependent behaviour of some visco-elastic materials can be modelled accurately in 1-D by including a stress contribution which depends non-linearly on strain rate. A visco-elastic model by Shim et al.[3] comprises a Voigt and Maxwell element in parallel and provides an effective representation of cancellous bone from the human cervi...

This paper investigates the influence of varying core density on the blast resistance of sandwich panels based on crosslinked PVC cores and aluminium alloy skins. Initially, the findings of a series of compression and single edge notch bend and shear tests are presented in order to characterise the strength and toughness characteristics of the foam...

This paper presents experimental and numerical results of an investigation to determine the response of quadrangular steel plates subjected to explosive charges buried under dry construction sand. The buried charges were designed to simulate a landmine blast. Three parameters; depth of burial, stand-off distance and mass of explosive, were varied t...

One-dimensional models for compaction of cellular materials exhibiting strain hardening are proposed for two different impact scenarios. The models reveal the characteristic features of deformation under the condition of decreasing velocity during the impact event. It was established that an unloading plastic wave of strong discontinuity propagates...

The experimental results and numerical simulations of “V” shape plates of different included angles (60°, 90°, 120°, 150° and 180° (flat plates)) subjected to localised blast load are presented in this paper. The results of simplified numerical models, carried out using Ansys/AutoDYN, are validated with experiments for deflection. The specimens are...

This paper details an investigation of the high strain rate compression testing of GFPP with the Split Hopkinson Pressure Bar (SHPB) in the through-thickness and in-plane directions. GFPP posed challenges to SHPB testing as it fails at relatively high stresses, while having relatively low moduli and hence mechanical impedance. The modifications to...

The use of thick fiber reinforced polymer (FRP) laminates in composite armor and naval structures requires thorough characterization of the through-thickness properties of said laminates, both quasi-statically and at high strain rates. Specimens cut from an E-Glass/vinyl ester FRP were tested in compression both quasi-statically and dynamically usi...

Thin-walled steel hollow sections are used extensively in the construction, offshore, mining and security industries. Such members subjected to blast loads are of interest due to increased security demands and the occurrence of accidental or intentional explosive events. This paper reports an experimental and analytical investigation of steel squar...

The response of composite sandwich structures to blast loading has received little attention from researchers when compared to the research performed on their metallic counterparts, despite the fact that composite sandwich panels are becoming more generally used in practice. This paper reports on a preliminary experimental investigation into the re...

This project studied the response of sandwich panel subjected to blast loading. The panels were based on two different face sheets (aluminium and woven glass-fibre/epoxy) and an aluminium honeycomb core. Experimental studies were carried out to analyse the effect of skin and core thickness on the blast response of the panels. The sandwich panels wi...

This article presents the results of an experimental investigation into the performance of perforated plates as a blast wave mitigation method in tunnel-like structures. Combinations of three different blockage ratios and three different separation distances (defined as the distance between the perforated plates and target plates) were used during...

This paper presents the results of experimental and numerical work on the response of sandwich panels made of thin-walled tubes and mild steel plates to axial loading.The core of the sandwich panels consists of mild-steel square tubes, 20×20×0.9 mm in cross-section, in three different layouts comprising of four or five or nine tubes, (panels A, B a...

Tunnels are vulnerable to devastating explosions, due to the concentration of explosive energy that would be many times greater than in an unconfined blast. One way to mitigate the damage resulting from an explosion is to disrupt the blast wave as it propagates along a tunnel. This paper presents the results of an investigation into the performance...

Lattice structures based on two simple architectures have been manufactured from 316L stainless steel using the selective laser melting process. The compressive properties of structures based on a body-centered cubic (BCC) and a similar structure with vertical pillars (BCC-Z) were initially investigated at quasi-static rates of strain. Blast tests...

The blast resistance of a carbon fiber-reinforced epoxy (CFRE) resin has been investigated through experiments on a range of panels. The panels were subjected to blast loading by detonating small quantities of plastic explosive at a fixed stand-off distance. A ballistic pendulum was used to provide a measure of the impulse imparted to the specimen....

The results of blast tests on sandwich panels with honeycomb cores are reported. Two core heights (13 mm and 25 mm) and two face sheet materials (glass fiber epoxy composite and aluminum alloy) were investigated. Increasing the core thickness reduced the permanent displacements exhibited by the sandwich panels. The panels with composite face sheets...

This article presents the results of an experimental and numerical investigation into the influence of hole size and thickness on the performance of mild steel perforated plates as a blast wave mitigation technique. Results of the blast tests showed that the perforated plates with small hole sizes reduced the damage imparted to the target plate by...

Sandwich panels constructed from metallic face sheets with the core composed of an energy absorbing material, have shown potential as an effective blast resistant structure. In the present study, air-blast tests are conducted on sandwich panels composed steel face sheets with unbonded aluminium foam (Alporas, Cymat) or hexagonal honeycomb cores. Ho...

This paper presents experimental data and numerical analysis of the effects of detonating explosive charges ranging from 1000 to 26288 kg laid out on the ground. The charges consist of different ordnances widespread in a carpet-like form. Numerical analysis using ANSYS/Autodyn are carried out with a view to gain a better understanding of the blast...

The effect of core density and cover plate thickness on the blast response of sacrificial cladding panels has been investigated through blast loading experiments and finite element modelling on structures with steel cover plates and aluminium foam cores. A range of foam core densities were examined, with 10%, 15% and 20% nominal relative densities....

The response of Fibre–Metal Laminates (FML) to localised blast loading is studied numerically in order to interpret the deformation mechanism due to highly localised pressure pulses causing permanent deformations and damage observed experimentally in FML panels comprising different numbers of aluminium alloy layers and different thickness blocks of...

A theoretical solution is obtained to predict the dynamic response of peripherally clamped square metallic sandwich panels with either honeycomb core or aluminium foam core under blast loading. In the theoretical analysis, the deformation of sandwich structures is separated into three phases, corresponding to the transfer of impulse to the front fa...

The mechanism of air blast attenuation in a sacrificial cladding comprising a steel cover plate and a foam core is examined applying an analytical and numerical analysis. For the range of the analysed pressure pulses, the maximum magnitudes of the induced compaction velocities were usually smaller than the acoustic wave speed in the foam material a...

This paper reports on an investigation into the behaviour of circular sandwich panels with aluminium honeycomb cores subjected to air blast loading. Explosive tests were performed on sandwich panels consisting of mild steel face plates and aluminium honeycomb cores. The loading was generated by detonating plastic explosives at a pre-determined stan...

This article presents the results of the experimental and numerical investigation into the effects of introducing welding into established laboratory scale tests of blast loaded stiffened plates. The experimental configurations, manufacturing details and results are presented. For a specific weld configuration an increasing stiffener height results...

An investigation into the response of a sandwich cladding panel under blast loading is presented. The sandwich cores are composed of square thin-walled metallic tubes. Three primary panel layouts are identified, consisting of panels with four, five and nine tubes within the core. Annealed mild steel and 6063-T6 aluminium alloy tubes are selected as...

This paper presents the numerical simulations of thin-walled square hollow steel beams subjected to a uniform transverse blast load. The objectives of the numerical simulations were to gain an insight into the temporal distribution of the global and local deformation and the adiabatic temperature rise in the beams as a result of impulsive loading....

GLARE© is a fibre-metal laminate that is widely used by the aircraft industry due to its excellent fatigue and impact properties. It has also been proposed as a blast resistant material. This article reports on a set of experiments on GLARE 3, one of the GLARE variants used in impact applications. Results from the preliminary blast tests indicate t...

Tests that investigate the inelastic response of blast-loaded sandwich structures, comprising mild steel plates and aluminium alloy honeycomb cores, are reported. The “uniform” loading was generated by detonating a disc of explosive and directing the blast through a tube towards the target. Localised blast loading was generated by detonating discs...

Finite element simulation is employed to analyse the behaviour of clamped sandwich panels comprising equal thicknesses mild steel plates sandwiching an aluminium honeycomb core when subject to blast loadings. Pressure-time histories representative of blast loadings are applied to the front plate of the sandwich panel. The FE model is verified using...

Extensive research activities in the field of blast loads have taken place in the last few decades. There are many experimental results related to underground explosions. The mechanism of crater formation is complex and it is related to the dynamic physical properties of air, soil and air/soil interface. Studies concerned with the characteristics o...

A Hopkinson Pressure Bar (HPB) was configured to perform spall testing on a glass fibre reinforced polymer (GFRP). The GFRP was woven roving E-glass in a vinyl ester matrix (Derakane 8084). The specimens were cylinders aligned in the through thickness direction, in order to test the interlaminar tensile strength at elevated strain rates. This testi...

A conical striker technique is presented for the dynamic compression of bone at uniform strain rates. It is shown that the strikers produce an incident pulse with an initial stress jump followed by a gradual rise that can be matched to the specimen hardening rate, resulting in a uniform strain rate test. Test results are presented at strain rates o...

In this paper, the failure of a pultruded glass fiber reinforced composite tube subjected to axial impact load transmitted by a small attached mass exposed to blast load is discussed. A numerical simulation is developed with LS-DYNA and is validated with experiments carried out on a ballistic pendulum by comparing the transmitted impulse by the exp...

Fiber–metal laminates (FML) are hybrid metal and composite structural materials that have been attracting interest due to the improved fatigue and impact resistance reported in the literature (J Mater Proc Tech 103:1–15, 2000; Int J Impact Eng 18(3):291–307, 1996; Compos Struct 61:73–88, 2003; Appl Comput Mater 11:295–315, 2004). Much less is known...

The ability of sandwich panels to resist dynamic loading has been shown to be superior to monolithic metal plates of the same areal density by a number of investigators. Experimental and numerical studies on the response of sandwich panels to air-blast, water-blast and “simulated blast” are increasing, but mainly focus on the latter two. Three type...

This two-part paper presents the results of experimental and numerical work on the crushing characteristics of square tubes, with blast-induced imperfections, subjected to axial load. In Part I, the experimental studies are presented. The approach in the studies involves creating imperfections on opposite sides at midlength of a square tube by mean...

This two-part article presents the results of experimental and numerical work on the crushing characteristics of square tubes, with blast-induced imperfections, subjected to axial load. In Part I, the experimental studies are presented. The approach in the studies involves creating imperfections on opposite sides at midlength of a square tube by me...

Copyright: 2009 Academy of Science of South Africa The Council for Scientific and Industrial Research (CSIR) conducts research into the effect of underwater explosions on maritime structures and equipment. One of the parameters that are required to be measured to a large degree of accuracy is the shock wave velocity in close proximity (10 - 120 cha...

This paper is Part II of a two-part article and presents the results of numerical simulations conducted to investigate the energy absorption characteristics of square tubes subjected to dynamic axial loading. Part I reports the experimental results of both quasistatic and dynamic tests. The validated model is used to study the crushing characterist...

This two-part article reports the results of experimental and numerical works conducted on the energy absorption characteristics of thin-walled square tubes with multiple circular hole discontinuities. Part I presents the experimental tests in which dynamic and quasistatic axial crushings are performed. The mild steel tubes are 350 mm in length, 50...

This paper reports on experimental and numerical investigations into the response of flexible sandwich-type panels when subjected to blast loading. The response of sandwich-type panels with steel plates and polystyrene cores are compared to panels with steel face plates and aluminium honeycomb cores. Panels are loaded by detonating plastic explosiv...

A series of localised blast loading experiments are performed in order to understand how the experimental set-up influences the impulse imparted to a plate. The imparted impulse is measured using a ballistic pendulum. The experimental results show that for both rigid and deformable plates the impulse measured by a ballistic pendulum increases as th...

A numerical investigation was carried out to evaluate the response of pultruded composite tubes, made of polyvinylester matrix reinforced uni-directionally with glass fibers, to axial blast loading. A full scaled model of the specimen was developed to simulate the experiments using LS-DYNA3D. The finite element solutions were validated using experi...

The crushing and energy absorption characteristics of thinwalled specimens consisting of single and axially stacked mild steel square tubes are investigated by the performance of quasi-static and dynamic axial crushing tests. Two tubes are axially stacked either by means of weld or a plate. Welded specimens comprise of two tubes of equal length axi...

This paper presents the rigid-plastic analysis of square hollow section steel beams subjected to transverse blast load. 35, 40 and 50mm square beams were subjected to a uniform transverse blast load and the impulse was measured using a ballistic pendulum. The energy consumed in the local cross-sectional deformation and the flexural beam bending def...

This article presents the results of experimental work on the crushing characteristics of single-cell and double-cell mild steel profiles with different dimensions and cross-sectional shape. The energy absorption characteristics and mode of collapse of seven double-cell profiles containing square and/or circular tubes is investigated with a view to...

This article presents the results of a series of blast tests on a carbon fiber-reinforced poly-ether-imide (PEI) and a glass fiber-reinforced PEI composite. Initially, the fracture properties of the two composite systems were characterized through a series of flexural and interlaminar fracture tests. Blast testing was then undertaken on a ballistic...