A triangular inverse shell element for efficient structural health monitoring of thin-walled structures

A recent study (https://doi.org/10.1002/msd2.12141) introduces a triangular inverse shell element, referred to as iKS3, offering an accurate yet computationally efficient approach to Structural Health Monitoring (SHM) of thin-walled structures. Developed within the framework of discrete Kirchhoff theory, the element enables accurate reconstruction of displacement fields from strain data while requiring significantly fewer sensors than existing methods. The iKS3 element has demonstrated effectiveness in detecting structural degradation in real-time, making it a promising candidate for SHM in aerospace, naval, and energy applications.

Thin shell structures are widely used in high-performance engineering due to their favorable strength-to-weight characteristics and capacity for distributed load-bearing. However, traditional Structural Health Monitoring (SHM)  strategies applied to such structures remain limited by high computational demands and reliance on dense sensor networks. Conventional inverse methods, typically based on the First Order Shear Deformation Theory (FSDT), are prone to shear locking and exhibit slow convergence when applied to thin geometries. These limitations necessitate the use of dense sensor networks to compensate for the slow convergence and high computational cost inherent in FSDT-based inverse formulations.

In response to these challenges, researchers from the National University of Sciences & Technology (Islamabad) and the University of Strathclyde (Glasgow) have developed the iKS3 element, as detailed in their article (DOI: 10.1002/msd2.12141) published in the International Journal of Mechanical System Dynamics. The iKS3 formulation is based on classical plate theory (CPT) assumptions, thereby eliminating the need for transverse shear strain components and avoiding the numerical difficulties associated with shear deformation modeling in thin shells.

Compared to FSDT-based inverse elements, iKS3 exhibits improved numerical stability and faster convergence, even under complex loading conditions. Validation studies conducted under in-plane, out-of-plane, and general load cases indicate that iKS3 consistently outperforms the inverse elements based on first-order shear Deformation Theory (FSDT). Its improved performance is attributed to the inherent exclusion of shear deformation terms, which simplifies the inverse formulation and enhances both computational efficiency and practical applicability.

In addition to displacement reconstruction, the method successfully detects and quantifies structural degradation based on a well-established damage index derived from reconstructed strain fields, enabling reliability. This combination of kinematic reconstruction and defect assessment strengthens its suitability for real-time SHM applications, where both computational efficiency and diagnostic accuracy are essential.

“The iKS3 element offers a computationally efficient path forward for monitoring thin-walled structures in real-time,” said Prof. Erkan Oterkus, co-author of the study. “By reducing the number of required sensors without compromising accuracy, it offers a practical solution for industry-scale monitoring systems.” This study, conducted under the supervision of Prof. Erkan Oterkus, directly addresses challenges associated with monitoring thin shell structures. By reducing the reliance on dense sensor networks and mitigating the numerical issues inherent in traditional FSDT-based inverse formulations, the iKS3 element presents a viable and efficient solution for real-world SHM applications. Its computational advantages and diagnostic capabilities represent a step forward in enabling efficient, scalable, and accurate monitoring of critical infrastructure in aerospace, naval, and energy sectors.

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References

DOI

10.1002/msd2.12141

Original Source URL

https://doi.org/10.1002/msd2.12141

About International Journal of Mechanical System Dynamics

International Journal of Mechanical System Dynamics  (IJMSD) is an open-access journal that aims to systematically reveal the vital effect of mechanical system dynamics on the whole lifecycle of modern industrial equipment. The mechanical systems may vary in different scales and are integrated with electronic, electrical, optical, thermal, magnetic, acoustic, aero, fluidic systems, etc. The journal welcomes research and review articles on dynamics concerning advanced theory, modeling, computation, analysis, software, design, control, manufacturing, testing, and evaluation of general mechanical systems.