Experimental investigations and analytical models for behavior of Grade 8.8 bolts and butt welds under heating and subsequent cooling

in kodur, venkatesh; Franssen, Jean-Marc (Eds.) Structures in Fire - Proceedings of the Sixth International Conference (2010, June 03)

The present article describes the experimental tests undertaken on Grade 8.8 tests and butt welds at the Centro Sviluppo Materiali during heating or subsequent cooling, presents a model for the force ... [more ▼]

The present article describes the experimental tests undertaken on Grade 8.8 tests and butt welds at the Centro Sviluppo Materiali during heating or subsequent cooling, presents a model for the force-displacement diagram of bolts during a natural fire that integrates the influence of the temperature history, and gives values of strength reduction factors for the cooling phase [less ▲]

Experimental investigations of the material behavior of Ti6Al4V titanium alloy

Report (2011)

Computer models are widely used to support the development of conventional design methods based on expensive full-scale tests or trial and error methods. Nevertheless, in order to accurately model metal ... [more ▼]

Computer models are widely used to support the development of conventional design methods based on expensive full-scale tests or trial and error methods. Nevertheless, in order to accurately model metal forming processes as well as structural behavior of load carrying elements, it is necessary to afford an accurate knowledge of the material properties. Titanium is one of the material for which various industrial sectors such as aerospace or biomedical are showing an increasing interest. This paper presents the experimental tests performed on the titanium based alloy Ti6Al4V to investigate on its mechanical behavior, especially in terms of its anisotropy and hardening. For that purpose, a classical uniaxial and a non-standard biaxial experimental equipments designed by Florès in the Materials and Structures Mechanics Laboratory of the University of Liège have been used to perform tensile, simple shear and cyclic shear tests as well as successive simple shear and plane strain tests, which provide the main contribution of this paper in the form of stress-strain curves. [less ▲]

Experimental investigations on the behaviour of a composite frame after the loss of a column

in Beale, R. G. (Ed.) Proceeding of the 6th International Conference on Steel and Aluminium Structures (2007, July 24)

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional loading, i.e. other accidental loads than ... [more ▼]

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional loading, i.e. other accidental loads than those already taken into consideration in the design process. According to Eurocodes and some other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most of the cases, no precise practical guidelines on how to achieve this goal are provided. Even basic requirements to fulfil are generally not clearly expressed. An European RFCS project called “Robust structures by joint ductility” has been set up in 2004, for three years, with the aim to provide requirements and practical guidelines allowing to ensure the structural integrity of steel and composite structures under exceptional loading through an appropriate robustness. This project involves analytical, numerical and experimental investigations; in particular, one substructure test simulating the loss of a column in a composite building, because of an unexpected impact, was performed in September 2006 at the University of Liège. This paper describes the experimental test carried out at the University of Liège, as part of this European project, and the first interpretation of the results. [less ▲]

Experimental lifetime determination in neutral praseodymium (Pr I) and neodymium (Nd I)

in Journal of Physics B-Atomic Molecular and Optical Physics (2004), 37(7), 1381-1389

Radiative lifetime measurements have been performed, with a time-resolved laser-induced fluorescence technique, for 18 even-parity levels of Pr I and 15 odd-parity levels of Nd I. The new results are ... [more ▼]

Radiative lifetime measurements have been performed, with a time-resolved laser-induced fluorescence technique, for 18 even-parity levels of Pr I and 15 odd-parity levels of Nd I. The new results are compared with the few experimental data available in the literature and good agreement is found. However, fragmentary knowledge of the spectra prevents reliable calculation of branching fractions and calls for additional laboratory efforts in order to provide the astrophysicists with reliable transition probabilities needed for investigating the magnetic fields in chemically peculiar stars. [less ▲]

Experimental method for the assessment of agricultural spray retention based on high-speed imaging of drop impact on a synthetic superhydrophobic surface

in Biosystems Engineering (2012), 112(1), 56-64

Spray retention is a critical stage in pesticide application since non-retained drops can result in reduced efficacy, economic loss and environmental contamination. Current methods of retention assessment ... [more ▼]

Spray retention is a critical stage in pesticide application since non-retained drops can result in reduced efficacy, economic loss and environmental contamination. Current methods of retention assessment are based either on field experiments or laboratory studies. The former are usually performed on whole plants under realistic spray application conditions but offer no insight into the physics behind the process whilst the latter mainly focus on drop impact physics but are usually restricted to unrealistically low drop speeds. The aim of the paper is to devise an experimental method to investigate retention at drop scale level as a function of operational parameters but under controlled realistic conditions. A device based on highspeed video was developed to study retention on a synthetic superhydrophobic surface for a moving agricultural nozzle. The sizes and velocities of the drops generated were measured immediately before impact using image analysis. Impact class proportions were established and transition boundaries between impact outcomes were quantified using Weber number. Two contrasting experiments were performed to investigate the ability of method to detect small parametric changes. The insignificant changes in spray pattern that occur from pressure changes, did not significantly affect impact class boundaries, but changed the proportion of drops in each class because of size and velocity variations. The use of a surfactant reduced the volume median diameter of the spray, increased impact speed and changed the impact class boundaries. The method should allow a precise parametric investigation of spray retention in laboratory and close to field conditions. [less ▲]

Experimental modal analysis of nonlinear vibrating structures using nonlinear normal modes

in IV European Conference on Computational Mechanics, Paris, 2010 (2010)

Experimental model for the study by chemiluminescence of the activation of isolated equine leucocytes.

in Research in Veterinary Science (1996), 61(1), 59-64

The activation of human polymorphonuclear leucocytes (the respiratory burst) can be studied by measuring their chemiluminescent response. This technique was adapted to equine leucocytes to investigate the ... [more ▼]

The activation of human polymorphonuclear leucocytes (the respiratory burst) can be studied by measuring their chemiluminescent response. This technique was adapted to equine leucocytes to investigate the effects of cell number, activator concentration, enhancers of chemiluminescence, pH, temperature and inhibitors. Leucocytes were isolated from citrated blood from healthy horses and chemiluminescence was measured with a Bio-Orbit luminometer sensitive to 900 nm light. The optimal cell density for the maximal chemiluminescent response ranged from 10(6) to 10(7) leucocytes 600 microliters-1. Chemiluminescence increased as a function of temperature, and the concentrations of luminol, lucigenin and phorbol myristate acetate (PMA), and was pH related (optimal pH value = 8.0 for lucigenin and 8.5 for luminol). The inhibition of chemiluminescence by 5 x 10(-5) M azide was 88 per cent for luminol and 37 per cent for lucigenin. Superoxide dismutase (100 IU) totally inhibited the chemiluminescence response. Approximately 30 per cent variability in chemiluminescence was observed under the same assay conditions, depending on the origin of the leucocytes. Based on these results, the conditions selected for the measurement of equine leucocyte chemiluminescence were: 10(6) to 10(7) leucocytes 600 microliters-1, 1 x 10(-6)M PMA, 1 mM luminol or 0.4 mM lucigenin, physiological pH (7.4) and physiological temperature (37.8 degrees C). These conditions were similar to those used for measuring the chemiluminescent response of human leucocytes. [less ▲]

Experimental models to study measles virus persistence in the nervous system

in Progress in Neuropathology (1983), 5

Experimental modulation of neurotransmitter phenotype in adult dorsal root ganglion neurons.

Conference (1990, June 30)

Experimental procedure and statistical data treatment for the kinetic study of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd-Ag sol–gel catalyst

in Chemical Engineering Journal (2011), 173(3), 801-812

The kinetics of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd- Ag/SiO2 catalyst was studied using an a priori experimental design with five independent variables—temperature ... [more ▼]

The kinetics of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd- Ag/SiO2 catalyst was studied using an a priori experimental design with five independent variables—temperature and partial pressures of 1,2-dichloroethane, hydrogen, ethylene and hydrogen chloride. A Langmuir–Hinshelwood model including two types of active site and the 1,2-dichloroethane adsorption as the rate-determining step was found to fit correctly with experimental data, according to the analysis of variance and the analysis of pondered residuals. The study allowed for catalytic deactivation. The rigorous experimental and statistical approach followed to carry out such a kinetic study is explained in detail. [less ▲]