Full-field full-stress-tensor identification of base-excited structures

Šonc, Jaša (author), Zaletelj, Klemen (author), Slavič, Janko (author)

Identifying the full-stress tensor over the surface of a vibrating structure is essential for design validation and vibration-fatigue-life estimation, yet current experimental methods provide only pointwise or incomplete stress data. Infrared cameras can provide non-contact, full-field surface-stress measurements on vibrating structures via the thermoelastic effect; however, they measure only the first stress invariant (i.e., the sum of the normal stresses at the free surface: σ$_{xx}$ + σ$_{yy}$). The individual stress components (σ$_{xx}$, σ$_{yy}$, τ$_{xy}$) required for a complete characterisation of the surface-stress state remain inaccessible from a single thermoelastic measurement. This article introduces a method that recovers the full-field, in-plane-stress power spectral density (PSD) field from thermoelastic camera data on a base-excited structure, demonstrated for thin, isotropic, metallic, plate-like structures under adiabatic conditions. First, a characterisation measurement identifies the hybrid stress-mode shapes containing all the plane-stress components by merging thermoelastic camera data with a simplified FE model through SEMM. Then, during operation under broadband random base excitation, the camera response is projected onto these mode shapes and expanded to the full-stress-tensor PSD. The method is validated experimentally on a clamped aluminium plate, identifying spatially resolved stress PSDs for all three in-plane components (σ$_{xx}$, σ$_{yy}$, τ$_{xy}$). The full-field first invariant σ$_{xx}$ + σ$_{yy}$ is measured experimentally; the individual components σ$_{xx}$, σ$_{yy}$ and τ$_{xy}$ are reconstructed through an experimentally corrected modal expansion informed by an FE stress basis, which supplies the inter-component ratios.

• Language: English
• Keywords: thermoelastic stress analysis, power spectral density, multiaxial vibration fatigue, SEMM, modal expansion, infrared camera
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 24 str.
• Numbering: Vol. 259, art. 114786
• PID: 20.500.12556/RUL-189537
• UDC: 534:620.178.3
• ISSN on article: 0888-3270
• DOI: 10.1016/j.ymssp.2026.114786
• COBISS.SI-ID: 294297603
• Publication date in RUL: 08.10.2026

Record is a part of a journal

• Title: Mechanical systems and signal processing
• Shortened title: Mech. syst. signal process.
• Publisher: Academic Press
• ISSN: 0888-3270
• COBISS.SI-ID: 169243

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: termoelastična analiza napetosti, spektralna gostota moči, večosno vibracijsko utrujanje, SEMM, modalna ekspanzija, infrardeča kamera

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0263
• Name: Mehanika v tehniki