Dear Colleagues,

Structural and material systems are a critical component of every country’s civil infrastructure and manufacturing industries. However, these systems are prone to damage and degradation due to normal aging, environmental actions, accidental events, etc. As a result, emerging technologies may be used to overcome challenges associated with damage and material degradation in engineering structures by facilitating greater cost-effectiveness and sustainability in the development, control, and management of such structures. One of these emerging technologies is structural health monitoring (SHM). In the strictest sense, SHM involves the analysis and observation of the engineering structures over time to monitor the state of their constituent materials or geometric properties by using periodically sampled measurements. In most cases, SHM is used to collect diagnostic data more optimally and cost-effectively by replacing non-essential maintenance with as-needed maintenance, thus allowing users to save the cost of unnecessary maintenance and eliminate unscheduled maintenance. It also allows for optimal use of engineering structures, reduction of human errors, minimization of downtime, and avoidance of catastrophic failures by providing constructors important guidance for improving their products as well as drastically changing the work and organization of maintenance services. Using SHM data, engineers can also establish a prognosis (evolution of damage, residual life, etc.) with the help of usage monitoring, thanks to the time dimension of monitoring (i.e., which makes it possible to consider the full history database of the structure).

In general, well-established approaches in SHM, such as virtual inspections and nondestructive testing (NDT) methods, are common tools to assess the damage in materials and structural systems. In fact, if we consider the first function alone, which focuses on the diagnosis of structural systems, it is possible to think that SHM is a new and improved way of performing NDT of structural systems. Although this is partly true, SHM is generally much more than just NDT/NDE because it also involves the integration of multiple sensors (possibly smart materials), data transmission, computational power, and processing ability inside the structures. This makes it possible to reconsider the structure design as well as the full management of the structure itself, and the structure considered as a part of wider systems. In most cases, SHM or NDT/NDE techniques may be time consuming, expensive, performed on a smaller scale, require damage location benchmarks, and are sometimes unable to provide accurate health conditions of large structures (i.e., particularly when dealing with deeply buried defects/damage) nor to deal with real-world problems. To overcome the aforementioned challenges, symmetry in SHM and NDT/NDE could be used to extract useful diagnostic information from a large amount of data by taking advantage of the natural symmetry in structural systems to obtain timely, qualitative and cost-effective analysis of complex structures in the shortest amount of time. In this Special Issue, we mainly discuss the application of symmetry in various SHM and NDT/NDE of structural systems including but not limited to: 

1. Application of signal processing methods for analyzing the symmetric information in SHM and NDT.
2. Numerical and FE analyses with reduced computational time in acquiring SHM information for symmetric structures.
3. Symmetric engineering structures and their SHM methodologies.
4. Mathematical modeling of symmetric engineering structures for SHM and NDT.
5. Symmetry in sensors arrangements/placements and methods of data collection for SHM and NDT.
6. Symmetric computational techniques for structural health monitoring.
7. Application symmetry in structural health monitoring and reliability estimation.
8. Symmetry beauty in engineering structural health monitoring.

Prof. Dr. Shuncong Zhong
Dr. Walter Nsengiyumva
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• symmetry
• symmetric structures
• structural health monitoring (SHM)
• nondestructive testing (NDT)
• nondestructive evaluation (NDE)
• structural diagnosis
• signal processing
• damage diagnosis
• damage identification and evaluation
• natural symmetry
• prognosis