Author
Manuela De Maddis
Other affiliations: Instituto Politécnico Nacional
Bio: Manuela De Maddis is an academic researcher from Polytechnic University of Turin. The author has contributed to research in topics: Welding & Spot welding. The author has an hindex of 7, co-authored 25 publications receiving 143 citations. Previous affiliations of Manuela De Maddis include Instituto Politécnico Nacional.
Papers
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TL;DR: In this paper, the effects of clamping force, welding current, and welding time on the microstructure, shear tension strength, and fracture of welded samples were investigated by evaluating the effect of different resistance spot welding of twinning induced plasticity (TWIP) and quenching and partitioning (Q&P) steel grades.
Abstract: Dissimilar resistance spot welding of twinning induced plasticity (TWIP) and quenching and partitioning (Q&P) steel grades has been investigated by evaluating the effects of clamping force, welding current, and welding time on the microstructure, shear tension strength, and fracture of welded samples. The spot welding of TWIP and Q&P steels promotes the occurrence of an asymmetrical weld nugget with a greater dilution of TWIP steel because of its lower melting temperature and thermal conductivity. As a result, weld nuggets exhibit an austenitic microstructure. TWIP steel undergoes a grain coarsening in the HAZ, whereas Q&P steel undergoes some phase transformations. Welded samples tend to exhibit higher shear tension strength as they are joined at the highest welding current, even though an improper clamping force can promote excessive metal expulsion, thereby reducing the mechanical strength of the welded joints. Shear tension welded samples failed through interfacial fracture with partial thickness frac...
36 citations
08 Nov 2016
TL;DR: In this article, the welding current, the electrode tip voltage and the electrical resistance of sheet stack were monitored in order to detect any metal expulsion and to evaluate its severity, as well as to clarify its effect on spot strength.
Abstract: This work aims at investigating the spot weldability of a new advanced Quenching and Partitioning (Q&P) steel and a Transformation Induced Plasticity (TRIP) steel for automotive applications by evaluating the effects of the main welding parameters on the mechanical performance of their dissimilar spot welds. The welding current, the electrode tip voltage and the electrical resistance of sheet stack were monitored in order to detect any metal expulsion and to evaluate its severity, as well as to clarify its effect on spot strength. The joint strength was assessed by means of shear and cross tension tests. The corresponding fracture modes were determined through optical microscopy. The welding current is the main process parameter that affects the weld strength, followed by the clamping force and welding time. Metal expulsion can occur through a single large expulsion or multiple expulsions, whose effects on the shear and cross tension strength have been assessed. Longer welding times can limit the negative effect of an expulsion if it occurs in the first part of the joining process. The spot welds exhibit different fracture modes according to their strengths. Overall, a proper weldability window for the selected process parameters has been determined to obtain sound joints.
25 citations
TL;DR: In this article, the authors presented analytical models to assess the performance of autonomous vehicle storage and retrieval systems (AVS/RS) pertaining to deep-lane racks, and validated these models through simulations performed on different warehouse layouts, in different deployment scenarios.
Abstract: In the last decades, huge efforts have been made to develop innovative solutions supporting the automation of logistics activities. Among the available technologies, autonomous vehicle storage and retrieval systems (AVS/RS) are very promising: they use light vehicles able to independently travel on different axes, and thus perform different tasks at the same time. Despite the increasing diffusion of such systems, there is still a lack of performance evaluation techniques. Furthermore, there are no standards available to provide performance evaluation criteria. In this paper, novel analytical models to assess the performance of AVS/RS pertaining to deep-lane racks. These models extend the state of the art by (i) taking into account the real criteria related to the storage and retrieval of items, (ii) considering the capability of the shuttle and the satellite to simultaneously perform different tasks, and (iii) evaluating the standard deviation of the cycle time, beside its average value. The presented models are validated through simulations performed on different warehouse layouts, in different deployment scenarios. The ultimate aim of such models is to support warehouse equipment designers in evaluating the performance of their systems, considering a multiplicity of realistic scenarios.
24 citations
TL;DR: In this article, the effects of the main important process parameters on the mechanical and microstructural properties of resistance spot welded TWIP sheets are examined by tensile shear tests and Vickers microhardness measurements.
Abstract: A widespread usage of new advanced high strength TWIP steels in the automotive industry is conditional on proper assembly operations by welding. Therefore, the effects of the main important process parameters on the mechanical and microstructural properties of resistance spot welded TWIP sheets are examined here. The welding parameters used were welding current, clamping force, and welding time. An L-9(33) orthogonally array was used to design the experimental tests. The mechanical response of the welded joints was assessed by tensile shear tests and Vickers microhardness measurements. The effect of the welding parameters on the fracture mode of the tensile shear specimens was also investigated. Some combinations of the welding process parameters guaranteed acceptable tensile shear strengths for the automotive industry. The tensile shear samples mainly failed by interfacial fracture mode, while partial thickness with pull out fractures were observed in the samples welded with the highest welding current and clamping force. Improper clamping force and welding current promoted excessive metal expulsions and, in turn, the formation of welding defects in the weld spots
21 citations
TL;DR: In this paper, the resistance spot welding between a quenching and partitioning (QP interfacial fractures only occur in the samples with the smallest nuggets) was investigated.
Abstract: This study investigates the resistance spot welding between a quenching and partitioning (QP interfacial fractures only occur in the samples with the smallest nuggets. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
15 citations
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31 Oct 2001
TL;DR: The American Society for Testing and Materials (ASTM) as mentioned in this paper is an independent organization devoted to the development of standards for testing and materials, and is a member of IEEE 802.11.
Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.
3,792 citations
TL;DR: The use of PLM processes and tools to manage product data effi ciently, with increased visibility and control over the life cycle of the product, is expanding.
Abstract: Manufacturers are faced with many challenges, such as globalization, disparate enterprise systems and a lack of platform maturity. These will only multiply as technology advances, offshore manufacturing increases and new ways of working emerge. To overcome these challenges, many manufacturers have embraced product lifecycle management (PLM) or have expanded the use of PLM processes and tools to manage product data effi ciently, with increased visibility and control over the life cycle of the product.
295 citations
TL;DR: Robotic handling systems are increasingly applied in distribution centers because they require little space, provide flexibility in managing varying demand requirements, and are able to work 24/7.
Abstract: Robotic handling systems are increasingly applied in distribution centers. They require little space, provide flexibility in managing varying demand requirements, and are able to work 24/7. This ma...
240 citations
TL;DR: In this paper, an intensive literature review on industrial information integration engineering (IIIE) is presented, which presents an overview of IIIE's content, scope and findings, and potential research opportunities.
180 citations
Journal Article•
167 citations