8 research outputs found
Semi-rigid floor-to-wall connections using side-framed lightweight steel structures : Concept development
No full textAuthor statement Alireza Bagheri Sabbagh: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Writing – original draft, Visualization, Shahabeddin Torabian: Conceptualization, Methodology, Validation, Investigation, Resources, Writing – review & editing, Visualization.Peer reviewe
Self-Heating Measurements for a Dual-Phase Steel under Ultrasonic Fatigue Loading for stress amplitudes below the conventional fatigue limit
No full textAbstractThe aim of the present research was to study the self-heating behavior of a dual-phase steel under ultrasonic fatigue loading for stress amplitudes lower than the conventional fatigue limit. The steel studied in this research was DP600 commercial dual phase steel. Fatigue tests were conducted for different values of stress amplitudes up to 107 cycles using an ultrasonic fatigue machine at a testing frequency of 20 kHz with flat specimens. An infrared camera was used to measure the mean temperature evolution during the tests. A specific form of heat diffusion equation was adopted in this work to calculate the intrinsic dissipation from temperature measurements. The variation of the dissipated energy versus stress amplitude under cyclic loading was also studied
Correlation of the high and very high cycle fatigue response of ferrite based steels with strain rate-temperature conditions
No full textThe discrepancies observed between conventional and ultrasonic fatigue testing are assessed through the mechanisms of dislocation mobility in BCC metals. The existence of a transition condition between thermally-activated and athermal regimes for screw dislocation mobility is studied under fatigue loading based on infrared thermography and microstructural characterization, here in the case of DP600 dual-phase steel. Evidence is obtained regarding the microstructural sources of crack initiation, which is found to be consistent with the existence of a transition in the modes of deformation. From the analysis of the experimental data gathered in this work, guidelines are given regarding the comparison and interpretation of S-N curves obtained from conventional and ultrasonic fatigue testing. The inevitable temperature increases under ultrasonic fatigue at high stress amplitudes along with the rate dependent deformation behavior of ferrite, as a BCC structure, were found as the key parameters explaining the observed fatigue behavior and thermal response under low and ultrasonic frequencies. A transition map was produced using the experimental results for DP600 steel as well as data available in the literature for other ferrite based steels, showing the correlation between thermally-activated screw dislocation movement and the absence of failure in very high cycle fatigue
Standardization of the processes and approach to an integrating tool. Study in Vodafone Italy
No full textLAUREA MAGISTRALEThis study has been done during the internship that the author had in “product engineering and solution” of Vodafone Italy. This team is a part of Technical enterprise service which provides different kinds of services to the corporates. The purpose of this study is increasing efficiency and effectiveness by standardizing the process of new services for enterprises and approaching to an integrating tool. The new service is a high speed and high performance networking which needs a new whole processes.
To bring forth, standardize the process is chosen and performed by reviewing the mission, defining new KPIs ,studying of all possible technical solutions, models and architectures and mapping new business process.
The standardized processes could bring the opportunity of creating a structured tool that can be used by all the process owners in order to carrying out their activity in an efficient and effectiveness way. At the end by investigating on the best practices projects it is tried to build up a tool that performs accurately
Calorimetric Studies and Self-Heating Measurements for a Dual-Phase Steel Under Ultrasonic Fatigue Loading
No full textThe objective of the present research is to study the self-heating behavior of a dual-phase (DP) steel under ultrasonic fatigue loading and to investigate the effect of frequency on intrinsic heat dissipation of the material. The steel studied in this work is DP600 commercial DP steel. Fatigue tests were conducted using an ultrasonic fatigue machine at a testing frequency of 20 kHz with flat specimens. An infrared camera was used to measure the mean temperature evolution during the tests. A specific form of heat diffusion equation was adopted in this work to calculate the heat dissipation per cycle from temperature measurements. The variation of this dissipation versus stress amplitude in cyclic loading was also studied
Thermal response of DP600 dual-phase steel under ultrasonic fatigue loading
No full textThe present work employed in situ infrared thermography to investigate the thermal response and dissipative mechanisms of a dual-phase steel under ultrasonic tension-compression fatigue testing. A classical thermal response occurred for stress amplitudes below 247 MPa but an abnormal thermal response was observed for stress amplitudes above 247 MPa, in that the temperature stabilized after a steep increase of up to 350 °C. The mean dissipated energy per cycle was estimated based on temperature measurements using the heat diffusion equation. The relationship between the mean dissipated energy per cycle and the stress amplitude was studied, and mechanisms related to the observed thermal response were discussed
Performance of CFS Walls Braced with Bridging and Sheathing
No full textThe objective of this paper is to describe testing and analysis of cold-formed steel (CFS) stud walls braced by both discrete steel bridging and gypsum sheathing. A focused series of tests was conducted to determine the strength of a typical CFS wall with discrete bridging, both with and without sheathing in place. The bridging was instrumented such that the forces developed as the bridging braced the studs under increased axial load could be measured. Bridging forces were measured
for walls where the sheathing was installed before loading, and for walls where the sheathing was applied after dead load – simulating panelized and stick construction sequences. It has been hypothesized that discrete bridging plays a limited role as bracing once wall sheathing has been applied – the test results conducted to date are consistent with this idea. Design methods exist for walls braced by discrete bridging or by sheathing, but methods do not exist for walls that rely on
both bracing methods. An existing design philosophy is extended to provide a new design method for combined bracing. The proposed design method is fully supported by engineering tools (spreadsheets. etc.) and is compared to the conducted testing. Recommendations are made for additional testing and analysis to finalize an efficient design method and philosophy that would allow CFS walls to take advantage of discrete steel bridging during construction, but otherwise use the strength provided by wall sheathing to stabilize the walls studs.This work was completed in part based on a grant from the American Iron and Steel Institute and the Steel Framing Industry Association titled “CFS Bracing Design Using Combinations of Discrete and Sheathing Bracing”. Steel materials for testing were donated by ClarkDietrich. Any
opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the employers and sponsors
Experiments on cold-formed steel moment-resisting connections with bolting friction-slip mechanism
No full textAcknowledgement The tests reported herein were conducted at the Structures Laboratory of Building and Housing Research Centre of Iran with technical support from Iran Tohid Co. which are much appreciated. The first author is grateful to the Elphinstone PhD Scholarship provided by the University of Aberdeen.Peer reviewe
