Dennis Gera

Dennis Gera

Palm Bay, Florida, United States
610 followers 500+ connections

Join to view profile

About

Dennis is an engineer (M.Sc.) who loves working with data and analytics, programming, and…

Contributions

Activity

Join now to see all activity

Experience & Education

  • Arado

View Dennis’s full experience

See their title, tenure and more.

or

By clicking Continue to join or sign in, you agree to LinkedIn’s User Agreement, Privacy Policy, and Cookie Policy.

Licenses & Certifications

Publications

  • Microstructure, mechanical and functional properties of refill friction stir spot welds on multilayered aluminum foils for battery application

    Journal of Materials Research and Technology

    The production of batteries often involves the joining of multilayered foils to a conductive tab. In the present study, a solid state spot welding method, the refill friction stir spot welding (refill FSSW), was employed for welding multilayered commercially pure aluminum (CP-Al) foils to 2024-T3 Al alloy sheets (tab). Defect-free welds with high lap shear strength (LSS) are obtained. In the stirred zone (SZ), 2024 Al alloy is only found within the shoulder refill region, which is greatly…

    The production of batteries often involves the joining of multilayered foils to a conductive tab. In the present study, a solid state spot welding method, the refill friction stir spot welding (refill FSSW), was employed for welding multilayered commercially pure aluminum (CP-Al) foils to 2024-T3 Al alloy sheets (tab). Defect-free welds with high lap shear strength (LSS) are obtained. In the stirred zone (SZ), 2024 Al alloy is only found within the shoulder refill region, which is greatly refined due to dynamic recrystallization. Unlike overlap joints in thicker sheets, a thermal-mechanically affected zone (TMAZ) also forms above the SZ in the probe refill region. “Stop-action” experiments have been conducted to describe joint formation. The presence of the 2024 Al alloy tabs resulted in significant changes to material follow behavior and the formation of microstructural zones not previously observed in conventional refill FSSW overlap welds in thicker sheets. Most welds failed in SZ pull-out mode during LSS test. The cracks initiate at the interface between the upper sheet and the first layer of the multilayered foils and then propagate upward and circumferentially outside the SZ. Welds of multilayered Al foils produced by refill FSSW show low contact resistance. The decomposition of electrochemically active materials in batteries can be avoided by maintaining a minimum distance from the spot-weld. The produced welds with flat appearance, high mechanical properties, and potential to meet industry requirements imply that refill FSSW is a promising welding technique for battery production.

    See publication

  • Comparison of a Cu-Al-Ni-Mn-Zr Shape Memory Alloy Prepared by Selective Laser Melting and Conventional Powder Metallurgy

    Transaction of Nonferrous Metals Society of China

    Apart from chemical composition, Shape Memory Alloys (SMAs) are known to have properties dependent on the thermal history of processing. Powder-based processing routes, such as powder metallurgy (PM) and selective laser melting (SLM), show many advantages over other conventional routes due to their ability to produce complex and unique parts. This work aims to investigate and critically analyze the differences in microstructural features and thermal properties of Cu-11.3Al-3.2Ni-3.0Mn-0.5Zr…

    Apart from chemical composition, Shape Memory Alloys (SMAs) are known to have properties dependent on the thermal history of processing. Powder-based processing routes, such as powder metallurgy (PM) and selective laser melting (SLM), show many advantages over other conventional routes due to their ability to produce complex and unique parts. This work aims to investigate and critically analyze the differences in microstructural features and thermal properties of Cu-11.3Al-3.2Ni-3.0Mn-0.5Zr shape memory alloy processed by selective laser melting and conventional powder metallurgy. The same chemical composition of the processed alloy guaranteed the presence of beta1’ martensite, irrespective of the processing route. However, due to higher heat input during processing, the conventional powder metallurgy samples also formed intergranular eutectoid constituents and stabilized austenite at room temperature. The specimens processed by SLM showed reversible martensitic transformation (T0 = 171ºC). PM-processed specimens did not show this transformation and consequently do not show a shape recovery.

  • The Influence of Sintering Parameters in the Microstructure and Mechanical Properties of a Cu–Al–Ni–Mn–Zr Shape Memory Alloy

    Advanced Engineering Materials

    Shape memory alloys from the Cu–Al–Ni system arouse interest for industrial applications due to their high thermal stability and low cost. In this study, the Cu–11.8Al–3.2Ni–3Mn–0.5Zr alloy is prepared through a powder metallurgy processing technique. Specimens are produced by a conventional uniaxial press followed by a sintering procedure under the argon atmosphere. The sintering temperature is varied in the range from 950 to 1060 °C, whereas sintering time is varied from 0.5 to 2 h. The…

    Shape memory alloys from the Cu–Al–Ni system arouse interest for industrial applications due to their high thermal stability and low cost. In this study, the Cu–11.8Al–3.2Ni–3Mn–0.5Zr alloy is prepared through a powder metallurgy processing technique. Specimens are produced by a conventional uniaxial press followed by a sintering procedure under the argon atmosphere. The sintering temperature is varied in the range from 950 to 1060 °C, whereas sintering time is varied from 0.5 to 2 h. The results denote that a temperature close to the alloy's solidus temperature is necessary to achieve higher densities. Moreover, martensite‐type microstructures are observed, despite the slow cooling rate applied after sintering. The compression strengths are in the order of 500 MPa, except for the specimens sintered for 1.5 h, which reaches an average of 700 MPa. This is explained by the lower porosity resulting from the liquid phase sintering. The forward and reverse martensitic transformation temperatures, however, are quite similar for all examined conditions.

    See publication

  • Welding Multilayer Materials by Refill Friction Stir SpotWelding

    The Minerals, Metals & Materials Society 2019

    To restrain global warming, automotive producers have adopted electric vehicle technology as one of the solutions to produce zero-emission cars as a replacement for fuel combustion cars. One of the challenges in the production of the battery for an electric vehicle is to weld thin electrode materials that have good electric conductivity, in multilayers configuration, which is challenging for conventional technologies. Refill friction stir spot welding is a spot-like joining process used as a…

    To restrain global warming, automotive producers have adopted electric vehicle technology as one of the solutions to produce zero-emission cars as a replacement for fuel combustion cars. One of the challenges in the production of the battery for an electric vehicle is to weld thin electrode materials that have good electric conductivity, in multilayers configuration, which is challenging for conventional technologies. Refill friction stir spot welding is a spot-like joining process used as a non-consumable tool to generate frictional heat during the process. Refill friction stir spot welding can weld various material combinations with good mechanical properties and surface quality. In this presentation, the capability of refill friction stir spot welding to join multilayer materials up to 80 layers of similar aluminum alloys will be presented. The presentation consists of the mechanical properties of the welds, electric conductivity/resistance of the welds, and the temperature measurement data during the welding process.

    See publication

  • Comparação da microestrutura da liga Cu- 11,8Al-3,2Ni-3Mn-0,5Zr processada via metalurgia do pó e conformação por spray.

    22º CBECIMAT

    Alloys with shape memory effect can recover their original shape after being plastically deformed. Cu-based alloys generally have a good combination of mechanical properties and shape memory, in addition to the low cost. However, for the properties to be adequate, it is essential to obtain fine and homogeneous microstructures. Therefore, in this study, a comparison was made between different manufacturing methods with great potential for achieving the desired microstructures. The…

    Alloys with shape memory effect can recover their original shape after being plastically deformed. Cu-based alloys generally have a good combination of mechanical properties and shape memory, in addition to the low cost. However, for the properties to be adequate, it is essential to obtain fine and homogeneous microstructures. Therefore, in this study, a comparison was made between different manufacturing methods with great potential for achieving the desired microstructures. The Cu-11,8Al-3,2Ni-3Mn-0,5Zr alloy was prepared via cold compaction and sintering, resulting in ø = 5 mm cylinders and also by the spray forming route, which resulted in a ø 300 mm circular deposit. The specimens were characterized by Optical Microscopy (MO) and Scanning Electron Microscopy (SEM). It was observed that in both cases, appropriate microstructures with grain sizes of the order of 100-200 µm were obtained. However, in the case of powder metallurgy, a significant influence of the cooling rate after sintering was noted to avoid the formation of phases that can lead to the degradation of shape memory properties, such as the capacity for reverse transformation.

    See publication

Projects

  • Data Pipeline

    -

    In this project, I've developed a sophisticated data pipeline using the Dagster framework in Python. The pipeline is designed to handle different environments, namely production and local, with resources configured accordingly.

    The pipeline integrates with various assets, including financial market assets and random assets, and is capable of executing a variety of jobs. It also includes a comprehensive set of schedules and sensors, demonstrating my ability to build complex, event-driven…

    In this project, I've developed a sophisticated data pipeline using the Dagster framework in Python. The pipeline is designed to handle different environments, namely production and local, with resources configured accordingly.

    The pipeline integrates with various assets, including financial market assets and random assets, and is capable of executing a variety of jobs. It also includes a comprehensive set of schedules and sensors, demonstrating my ability to build complex, event-driven data pipelines.

Honors & Awards

  • Honorable Mention

    DEMaEx - Associação dos Ex-Alunos de Engenharia de Materiais da UFSCar

    Honorable mention for participation in the “Professor Sérgio Mascarenhas Oliveira ”, offered to students who stood out among the 2019 graduates through excellent academic performance throughout the undergraduate course in Engineering of Materials.

Languages

  • English

    Native or bilingual proficiency

  • Portuguese

    Native or bilingual proficiency

  • Spanish

    Elementary proficiency

Recommendations received

2 people have recommended Dennis

Join now to view

More activity by Dennis

View Dennis’ full profile

  • See who you know in common
  • Get introduced
  • Contact Dennis directly
Join to view full profile

Other similar profiles

Explore more posts

Explore collaborative articles

We’re unlocking community knowledge in a new way. Experts add insights directly into each article, started with the help of AI.

Explore More

Others named Dennis Gera

5 others named Dennis Gera are on LinkedIn

See others named Dennis Gera

Add new skills with these courses

See all courses