Arild Holm Clausen

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• PhD
• Professor at Norwegian University of Science and Technology

In the case of aluminium structures, welding may introduce weak zones, so-called heat-affected zones (HAZ), close to the weld. Such zones should be accounted for when predicting the overall behaviour of structures since the deformation tends to localise within such weak zones leading to the initiation of failure. Whereas the effect of welding on me...

Poly-vinylidene fluoride (PVDF) is a semi-crystalline thermoplastic featuring a high chemical resistance, good thermal stability, and high pressure resistance, rendering it attractive for a wide range of engineering applications. This study assesses the influence of temperature, strain rate, and stress triaxiality on the large-strain response of a...

This paper addresses numerical modelling of a rolled, austenitic stainless steel of grade AISI 316L, corresponding to EN 1.4404. The study comprises uniaxial tension tests at a range of temperatures (from –20°C to 200°C) and at two different strain rates (10–3 s–1 and 10–1 s–1). It appears that the material is very ductile and hardens significantly...

This study compares the mechanical behaviour of square hollow sections (SHS) made of three different types of S355: cold-formed, hot-rolled and offshore steel. A material model and failure criterion for each steel type were calibrated based on quasi-static uniaxial tensile tests. The failure criterion applies a recently proposed through-thickness d...

This article presents a simple progressive damage model for quasi-brittle materials, combining orthotropic elasticity with a scalar damage model including spatial variation of the damage initiation strain and the crack band method for softening regularization. The model’s performance is first analyzed from a numerical point of view and then demonst...

The chemically induced embrittlement of polyamide 11 (PA11) has been the subject of a considerable research effort to understand and predict the degree of embrittlement based on the material's intrinsics. However, the presence of highly complex loading scenarios and stress states in real-world structures raises the question of whether extrinsic fac...

Deformation-induced cavitation influences the mechanical response of polymeric materials, but acquiring in situ measurements of the spatial evolution of cavities has typically necessitated the use of synchrotron radiation sources. The objective of this study is to develop and demonstrate a method allowing for in situ measurements of deformation-ind...

This paper presents an experimental investigation of injection-moulded short glass-fibre reinforced polyamide-6 reinforced with 0 wt.%, 15 wt.% and 30 wt.% fibres. The fibre orientation distributions are characterized by use of X-ray computed tomography. A shell-core-shell structure is found through the thickness of the materials, where the predomi...

Polymer foams are often used for impact mitigation and protection due to low weight and excellent energy absorbing capability. Depending on the application, different loading rates and environmental conditions can be expected, including various operating temperatures. In this paper, experimental results from mechanical testing of expanded polypropy...

The deformation-induced dilation of mineral-filled polyvinyl chloride (PVC) is investigated by means of polychromatic X-ray absorption tomography (XCT). Axisymmetric notched tensile specimens are strained to prescribed elongations using a tensile test apparatus and subsequently scanned by XCT after relaxation. During straining, surface deformations...

A novel method for measuring and calculating volumetric strain in circular cylindrical uniaxial tension samples made from polymeric materials is proposed. It is shown that special considerations must be taken when calculating volumetric strain when a sample is in a postnecking state. Solely based on surface data, the key feature of the proposed cor...

The use of adhesives in load-carrying structures and components has increased recently, especially in the automotive industry. There has been many studies on structural adhesives, but when it comes to semi-structural adhesives, there is a lack of literature. In this article, a semi-structural two component polyurethane adhesive has been studied exp...

The influence of stress triaxiality and strain rate on the tensile behaviour of mineral-filled polyvinyl chloride (PVC) is investigated in this paper. Axisymmetric notched tensile specimens with notch radius equal to 20 mm, 5 mm and 2 mm were tested at three nominal strain rates of 0.0001s− ¹ , 0.001s− ¹ and 0.01s− ¹ . Surface deformations were mea...

In this study, a thermo-elasto-viscoplastic model is developed for a low density cross-linked polyethylene (XLPE) in an attempt to describe the combined effects of temperature and strain rate on the stress-strain response and the self-heating of the material at elevated strain rates. The proposed model consists of two parts. On the one side, Part A...

The uniaxial stress-strain curve provides an important piece of information within several fields of engineering. Design of civil engineering and transport-related structures requires knowledge of stiffness properties, yield strength, and possibly also hardening behaviour and fracture characteristics for the material at hand. People working with ma...

The above article, published online on 13 September 2017 in Wiley Online Library [1], has been retracted by agreement between the authors, the journal editors, and Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. The retraction has been agreed as this article is a duplicate of the version published on 10 Augu...

Finite element (FE) simulations can be a powerful tool for predicting the response of fillet welds subjected to various types of loading. This requires that the fillet welds are modelled adequately, which can be a great challenge. Capturing the correct evolution of material damage and failure in the welds can be particularly difficult. This paper i...

Bolt and nut assemblies under tension loading can either fail by bolt fracture or thread failure. The latter failure mode is arguably undesired because it leads to failure at a comparatively low deformation level. Moreover, incipient thread failure is challenging to detect in the case of over-tightening since the bolt remains in the bolt hole after...

(This paper was submitted to the Eurosteel 2017 conference, and was selected to be published in Steel Construction) Bolt and nut assemblies under tension loading can either fail by bolt fracture or thread failure. The latter failure mode is arguably undesired because it leads to failure at a comparatively low deformation level. Moreover, incipient...

Fillet welding is widely used in connections in civil engineering and marine structures. Thus, understanding the behaviour of fillet welds under various types of loading is important, and numerical simulations can provide increased insight into this topic. This paper concerns finite element simulations of previous quasi-static and dynamic (impact)...

In the present work, we investigate the effects of strain rate (0.01 1/s, 0.1 1/s and 1.0 1/s ) and low temperature ( -30 °C, -15 °C, 0 °C, and 25 °C) on the mechanical behaviour in tension and compression of two materials: a rubber-modified polypropylene copolymer (PP) and a cross-linked low-density polyethylene (XLPE). Local stress-strain data fo...

A common presumption for elastomeric material behaviour is incompressibility, however, the inclusion of filler particles might give rise to matrix-particle decohesion and subsequent volume growth. In this article, the volumetric deformation accompanying uniaxial tension of particle-filled elastomeric materials at low temperatures is studied. An exp...

Virtually no studies in the open literature are concerned with the behaviour of fillet welds under impulsive loading, which may occur due to actions such as explosions and impact. We therefore developed a novel test setup allowing for measurements of the force and the deformation of fillet welds subjected to impact load conditions. The test specime...

Laboratory tests show that there is a pronounced difference in the volumetric response between uniaxial tension and confined axial compression loading for commercial particle-filled hydrogenated nitrile butadiene rubber (HNBR) and fluoroelastomer (FKM) compounds. In uniaxial tension (UT), a volume increase of 5 and 20 % for the HNBR and FKM respect...

Thread failure of bolt and nut assemblies subjected to tension is generally undesired because it is a less ductile failure mode than fracture of the threaded shank of the bolt (denoted bolt fracture). Another issue is that incipient failure of the threads due to over-tightening is difficult to detect during installation. Thus, it is appropriate to...

In this study, we present a method to determine the large-strain tensile behaviour of polymers at low temperatures using a purpose-built temperature chamber made of polycarbonate (PC). This chamber allows for several cameras during testing. In our case, two digital cameras were utilized to monitor the two perpendicular surfaces of the test sample....

Both accidental and intentional actions may impose extreme impulsive loading to the beam-to-column joints of a building. Limited knowledge concerning the behaviour of joints subjected to such loadings has been developed. Therefore, the authors have studied, both experimentally and numerically, the response of a beam-to-column joint configuration ex...

Limited documentation is concerned with the behaviour of steel joints subjected to severe impulsive loading originating from incidents such as explosions or impact. In this paper, finite element simulations are used to investigate the behaviour of beam-to-column joints with bolted end-plate connections subjected to impact loading. An elastic-thermo...

This paper presents a physically-based constitutive model applied to an AA6082 aluminium alloy subjected to large strains, high strain rates and elevated temperatures. The model accounts for thermo-elasticity, thermo-viscoplasticity, and strain-rate and temperature dependent work hardening, using the dislocation density as an internal variable with...

The thermo-mechanical behaviour in tension of three as-cast and homogenized Al-Mg-Si alloys, distinguished by their Mg and Si content, was investigated at a wide range of strains (the entire deformation process up to fracture), strain rates (0.01-750 s-1) and temperatures (20-350 °C). The alloys were shown to have isotropic plastic behaviour. Low a...

This article presents uniaxial tension tests of three different elastomer compounds commonly applied as seal materials in the oil and gas industry. The tests were performed at five different temperatures, ranging from −20 to 150 °C. Optical measurements were used to ensure high quality stress–strain data. The material samples were exposed to a cycl...

There is limited knowledge on the behaviour of beam-to-column joints subjected to extreme impulsive loading. A double-sided beam-to-column joint configuration was therefore tested in impact load conditions. The test specimens consisted of H-section beams and col- umns that were joined by end-plate connections and high-strength bolts. The results sh...

Many actions, such as accidental or malicious explosions, may impose high loading rates to structural frames. To enhance the knowledge of the behaviour of joints subjected to severe impulsive loading, a double-sided beam-to-column joint configuration was tested at quasi-static and dynamic loading rates. The test specimens consisted of H-section bea...

The thermo-mechanical behaviour in tension of an as-cast and homogenized AA6060 alloy was investigated at a wide range of strains (the entire deformation process up to fracture), strain rates (0.01–750 s−1) and temperatures (20–350 ∘C). The tests at strain rates up to 1 s−1 were performed in a universal testing machine, while a split-Hopkinson tens...

In an attempt to improve the constitutive models for 6xxx aluminium alloys at high temperatures and high strain rates, a comprehensive test series has been carried out for AA6060. Uniaxial tension tests were performed at various strain rates from 0.01 s⁻¹ to 1000 s⁻¹ and temperatures from 20 °C to 350 °C. The tests were carried out using a standard...

A split-Hopkinson tension bar system is modified to allow for measuring the stress–strain behaviour of ductile materials at large strains, high strain rates and elevated temperatures. The specimen is heated by induction, and a pyrometer provides a laser-based temperature measurement that controls the testing temperature in a feed-back loop. A high-...

This paper addresses the deformation of axisymmetric tensile bars, made of mineral-filled PVC and HDPE, with and without pre-machined notch. The purpose of the study is both to investigate the mechanical behaviour under various stress triaxialities, induced by different notch radii, and the capabilities of a phenomenological constitutive model. The...

The nucleation and growth of voids in mineral-filled PVC have been investigated through experimental and numerical studies. Uniaxial tensile specimens were deformed in tension to different elongation levels and then unloaded. The macroscopic strain fields were recorded by use of digital image correlation. After the test, the microstructure of the d...

Aluminium alloys are commonly used by the industry due to their good mechanical properties and their relatively low density. An accurate prediction of the behaviour of aluminium alloys under a wide range of temperatures and strain rates is important in numerical simulations of forming processes or applications involving adiabatic heating like penet...

This paper shows how experimental test results from a split-Hopkinson tension bar (SHTB) and numerical simulations of the test set-up can be used for mutual verification. Firstly, a SHTB where the tension stress wave is generated by pre-stretching a part of the incident bar is briefly presented. This SHTB is used to carry out tensile tests of four...

This article presents an experimental investigation of a ductile rubber-modified polypropylene. The behaviour of the material is investigated by performing tension, shear and compression tests at quasi-static and dynamic strain rates. Subsequently, scanning electron microscopy is used to analyse the fracture surfaces of the tension test samples, an...

The paper presents an experimental investigation of a semi-ductile rubber-modified polypropylene reinforced by mineral particles. The behaviour of the material is investigated by performing tension, shear and compression tests at quasi-static and dynamic strain rates, applying digital image correlation for full-field strain measurements. Subsequent...

This paper presents first material tests on HDPE and PVC, and subsequently impact tests on plates made of the same materials. Finally, numerical simulations of the plate impact tests are compared with the experimental results. A rather comprehensive series of mechanical material tests were performed to disclose the behaviour of PVC and HDPE in tens...

The dynamic fracture behaviour of extruded AA6xxx and AA7xxx aluminium alloys is investigated using an instrumented Charpy test machine and V-notch specimens. The specimens are made from extruded flat profiles with a rectangular cross-section of 10 mm thickness and 83 mm width. The material is in T6 temper, i.e. the peak hardness condition. The all...

The stress–strain behaviour of extruded AA6xxx and AA7xxx aluminium alloys in T6 temper was studied at a wide range of strain rates. Tensile tests at low to medium strain rates were performed in a standard tensile test machine, while a split-Hopkinson tension bar was used to carry out tests at high rates of strain. Extruded aluminium alloys have an...

This paper presents quasi-static and dynamic tests on circular clamped plates made of a PEHD thermoplastic. A brief review of the main results from a material test programme, involving tension and compression tests at different rates, is also provided. The results from the material tests are used to identify the coefficients of a recently proposed...

A hydro-pneumatic machine for performing material tests at intermediate strain-rates is described, and the principle of operation is given. The behaviour and operation of the hydro-pneumatic machine are further evaluated by an analytical model and non-linear finite element analysis. Several tests were conducted on Weldox 460E steel and aluminium al...

The present paper is aimed at studying the effect of pre-straining on the localisation and fracture in dual-phase steel under dynamic loading conditions. This study was conducted by using tensile tests at elevated rates of strain.A dual-phase steel DP800 sheet of thickness 1.5 mm was pre-deformed to three different levels of effective strain 1%, 4%...

Dynamic compressive curves of high density semi-crystalline polyethylene, PEHD, were obtained via the Split Hopkinson Pressure Bar, SHPB, technique. The SHPB was fitted with polymeric bars, PMMA, to avoid a large impedance mismatch between the specimens and the bars. As a consequence, attenuation and dispersion had to be taken into account. Care wa...

Nonlinear finite element simulations of Charpy V-notch impact tests are carried out for two 6xxx aluminium alloys having recrystallized and non-recrystallized grain structure and significantly different strength and ductility. These alloys have applications in automotive safety components such as bumper beams and crash boxes. In a crash situation,...

Thin plates of high-strength steel are frequently being used both in civil and military ballistic protection systems. The choice of alloy is then a function of application, ballistic performance, weight and price. In this study the perforation resistance of five different high-strength steels has been determined and compared against each other. The...

This paper aims at evaluating an elastoplastic constitutive model which accounts for combined isotropic-kinematic hardening for complex strain-path changes in a dual-phase steel, DP800. The capability of the model to reproduce the transient hardening phenomena under two-stage non-proportional loading has been assessed through numerical simulations...

The elastic-plastic behaviour of dual-phase, high-strength steel sheets under two-stage strain-path changes has been investigated. Three different loading sequences, namely monotonic, 45° tensile path changes and orthogonal tensile path changes complied by sequences of simple uniaxial tensile tests, were analysed at room temperature. From the exper...

Tensile tests were conducted on dual-phase high-strength steel in a Split-Hopkinson Tension Bar at a strain-rate in the range of 150-600/s and in a servo-hydraulic testing machine at a strain-rate between 10-3 and 100/s. A novel specimen design was utilized for the Hopkinson bar tests of this sheet material. Digital image correlation was used toget...

Large plastic deformation in sheets made of dual phase steel DP800 is studied experimentally and numerically. Shear testing is applied to obtain large plastic strains in sheet metals without strain localisation. In the experiments, full-field displacement measurements are carried out by means of digital image correlation, and based on these measure...

Thin plates of high-strength steel are frequently being used in ballistic protection systems. In this study, the perforation resistance of three different high-strength steel alloys impacted by 7.62 mm AP projectiles has been determined and compared against each other. The considered alloys are Weldox 500 E, Hardox 400 and Domex Protect 500. The yi...

This paper presents the experimental set-up for high strain-rate tests at elevated temperatures in a split-Hopkinson tension bar. A high current was sent through the specimen, whereby direct resistance heating increased the temperature in the material to 300$^{\circ}$C within a few seconds. Such a fast increase reduces the heat transfer to the bars...

Quasi-static and dynamic axial crushing tests were performed on thin-walled square tubes and spot-welded top-hat sections made of high-strength steel grade DP800. The dynamic tests were conducted at velocities up to 15 m/s with an impacting mass of 600 kg in order to assess the crush behaviour, the deformation force and the energy absorption. Typic...

Experimental data from uniaxial tensile tests on smooth and notched specimens of aluminium alloy 5083-H116 show that the material exhibits negative strain-rate sensitivity for strain rates within a certain range. The negative strain-rate dependence, which is attributed to dynamic strain aging, leads to serrated stress–strain curves, discontinuous p...

Extruded aluminium panels find their use in many different structures such as offshore platforms, bridge decks, train and ship components and lightweight protection systems. Impacts or other types of high-speed loading conditions are thus a relevant issue for several of these applications. There are, however, not many investigations published on th...

The interest regarding use of aluminium alloys in lightweight protective structures is today increasing. Even so, the number of experimental and computational investigations giving detailed information on such problems is still rather limited. In this paper, perforation experiments have been performed on AA5083-H116 aluminium plates with thicknesse...

This paper presents a part of an on-going study of light-weight shelters made of aluminium alloy AA5083–H116. A necessary prerequisite for numerical simulations of impact behaviour of such shelters is a calibrated numerical model. Slightly modified versions of the two Johnson–Cook models describing flow stress and fracture strain are applied. In ad...

The interest regarding use of extruded aluminium panels as lightweight protective structures is cmrently increasing. Even so, there are few experimental and computational investigations considering such structures. This paper presents some perforation tests on AA6005-T6 aluminium panels impacted by ogival-nose steel projectiles, where special empha...

We give in this paper a possible mechanical interpretation to the development of uders front and Portevin-Le-Chatelier effect based on a band analysis for an elastic-viscoplastic material with negative strain-rate sensitivity. This negative strain rate sensitivity allows for jumps for the plastic strain rate which in turns permits the existence of...

In civil engineering education, architectural topics like aesthetics and creative design have received scant attention at many universities. This paper describes how elements of these issues can be introduced in a structural steel design course, with special emphasis on the design of bridges. An important part of the activities described is a proje...

This work was initiated to study the influence of geometry and material variations on the structural response of an aluminum I-beam subjected to concentrated loading. The beam behavior was computed with a previously validated LS-DYNA model, and an analytical response surface expression for the maximum load capacity was established. The deviation be...

The increasing demand for aluminium extrusions calls for relevant statistical data to establish objective measures of uncertainties associated with the material description and cross-sectional geometry. A total of 392 tensile test specimens are machined from 49 rectangular hollow section extrusions in order to investigate how the material propertie...

Stretch bending is a process of considerable importance for plastic forming purposes. Effective operations in the industry demand sufficient knowledge of how different parameters influence the process as well as the final shape of the product. Numerical simulations are an effective way of investigating these issues. However, the numerical model mus...

In civil engineering education, architectural topics like aesthetics and creative design have received scant attention at many universities. This paper describes how elements of these issues can be introduced in a structural steel design course, with special emphasis on the design of bridges. An important part of the activities described is a proje...

Stretch bending of two generic aluminium bumper sections are investigated experimentally and numerically. Six different stretch bending procedures, herein denoted tensile sequences, are studied. Laboratory tests are performed for one of these sequences, finding that the numerical model represents the observed behaviour satisfactorily. A sequence wi...

An experimental stretch bending study is presented in this paper. A total of 29 tests on 2 m long rectangular hollow section aluminum specimens were performed in a purpose-built stretch bending rig. The tests were carried out under different tensile force combinations, or tensile sequences, in order to investigate the influence of the force on cert...

An experimental stretch bending study is presented in this paper. A total of 24 tests on 2-m-long rectangular hollow section aluminum specimens are performed in a specially designed stretch bending rig. All tests are carried out with a constant tensile force corresponding to the material's yield stress. Factorial analysis is systematically used in...

Quasi-static and dynamic axial crushing tests were carried out on thin- walled square tubes and spot-welded top-hat sections made of high-strength steel grade DP800. The tests were conducted at velocities up to 15 m/s with an impacting mass of 600 kg in order to observe the crush behaviour, the reaction force and the energy absorption of the thin-w...

This paper presents an implementation of a material model for thermoplastics. Such materials have a quite complex behavior involving large elastic and plastic deformations, strong viscous and temperature effects, possible true stress softening and deformation-induced anisotropy. The demand of reliable constitutive models for thermoplastics is incre...