Innovative approaches of stress shot peening and fatigue assessment for the development of lightweight, durability-enhanced automotive steel leaf springs

Project Scope and Objectives

Scope & Objectives

The project is devoted to the elaboration and exploitation of novel R&D models for accurate durability enhancement and assessment of automotive suspension components, focusing on leaf springs. The project outcomes should build an innovating R&D platform with sophisticated, scientific background and comprehensive experimental validation that will be widely applied for the development of engineering components with high requirements on durability and lightweight. The following technological objectives are followed within the framework of LIGHTTECH:

  1. Development and experimental validation of novel FEM-based elastoplastic Stress Shot Peening (SSP) simulation models, taking into account the decarburization of the failure-critical surface layers to calculate the states of roughness, residual stresses, and work hardening in the surface area, depending on the SSP process parameters. Therewith, they will contribute to the optimization of SSP processes.
  2. Development and experimental validation of a modularly structured, innovate analytical fatigue life calculation model, applicable in any stage of development depending on the input data level (material data / leaf specimen data / full-scale spring prototype data), independent from or in conjunction with the SSP simulation model. Creation of a comprehensive experimental database of monotonic and cyclic material properties at every manufacturing stage (raw, after heat-treatment and tapering, after SSP). They will be used for the input and validation of the theoretical models mentioned above as well as for further related engineering applications beyond the scope of the present
  3. Creation of a comprehensive experimental database of monotonic and cyclic material properties at every manufacturing stage (raw, after heat-treatment and tapering, after SSP). They will be used for the input and validation of the theoretical models mentioned above as well as for further related engineering applications beyond the scope of the present project.
  4. Development of two lightweight, high-performance full-scale leaf springs, of high industrial interest, with exceptional strength and fatigue performance requirements. The project aims to support the European leaf spring manufacturers, the associated steel producers and the end-users (OEMs) with novel technologies enabling optimized surface treatment and systematic, knowledge-based development of new, enhanced leaf springs, not attainable with the current technologies. On the same time, the overall product quality, in terms of weight saving, sufficient robustness, durability and safety, will be enhanced.

The project aims to support the European leaf spring manufacturers, the associated steel producers and the end-users (OEMs) with novel technologies enabling optimized surface treatment and systematic, knowledge-based development of new, enhanced leaf springs, not attainable with the current technologies. On the same time, the overall product quality, in terms of weight saving, sufficient robustness, durability and safety, will be enhanced.

Publications

Research Publications

  1. Investigation of the shot size effect on residual stresses through a 2D FEM model of the shot peening process.

    C. Gakias, G. Maliaris and G. Savaidis. Submitted to Metals 2022, 12(6), 956, https://doi.org/10.3390/met12060956

  2. A FEM-Based 2D Model for Simulation and Qualitative Assessment of Shot-Peening Processes.

    G. Maliaris, C. Gakias, M. Malikoutsakis and G. Savaidis. Materials, 14, 2784 (2021), https://doi.org/ 10.3390/ma14112784.

  3. Stress-Shot-Peened Leaf Springs Material Analysis through Nano- and Micro-Indentations.

    M. Pappa, G. Savaidis and N. Michailidis. Materials, 14, 4795 (2021), https://doi.org/10.3390/ ma14174795.

  4. Characterization and performance of high strength steel 51CrV4 under cyclic loading.

    M. Malikoutsakis, I. Makris, A. Pagonas and G. Savaidis. MATEC Web of Conference 349, 02008 (2021), https://doi.org/10.1051/matecconf /202134902008.

Project Beneficiaries

Beneficiaries
Thessaloniki, Greece

Aristotle University of Thessaloniki

AUTH is the Project Coordinator. The Laboratory of Machine Elements & Machine Design and the Physical Metallurgy Laboratory will have a major role in the accomplishment of the theoretical models and will contribute to fatigue testing of material specimens, leaf specimens and full-scale leaf spring prototypes.

VISIT
Germany

MAN

MAN’s expertise is decisive for the elaboration of the full-scale leaf spring specifications. It will provide the corresponding design specifications, the testing load spectra for the trial tests, and will perform the final durability and functionality tests.

VISIT
Bochum, Germany

Bochum University of Applied Sciences

The main responsibilities of HBO within the proposed project are the execution and assessment of residual stress measurements throughout the project duration, the development of the crucial, material-dependent optimized SSP parameters, and the organization of the final workshop for the dissemination of the project results.

VISIT
Germany

SOGEFI Group

SOGEFI will construct the “conventional” spring and provide its knowledge in optimized Heat-Treatment and Tapering (HTT) processes and surface treatment (SSP) processes.

VISIT
Spain

Muelles y Ballestas Hispano Alemanas (MBHA)

MBHA will construct the “enhanced” spring and provide its knowledge and individual SSP process data required for the SSP simulations, the corresponding leaf specimens in HTT and optimized SSP conditions to verify the SSP simulations and the experimental S-N curves from the corresponding leaf specimens.

VISIT
Germany

saarstahl

Top steel producer with high R&D-level, SAG will provide its expertise for application of the most promising steel grades (conventional, enhanced) to fulfil the requirements and criteria for the new leaf spring applications treated in the proposed project

VISIT

Contact

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Location

Aristotle University of Thessaloniki, Panepistimioupoli - University Campus

E-mail

gsavaidis@auth.gr

Phone

+302310996005