Saudi Cultural Missions Theses & Dissertations
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Item Restricted Damage identification in plate structures using dynamic response(Saudi Digital Library., 2026) Alshammari, Yousef Lafi Ateeq; Khan, MuhammadStructural Health Monitoring (SHM) extensively relies on dynamic response measurements to assess the condition of engineering structures and detect damage. Cracks in plate structures represent a significant concern in engineering, as they can affect the integrity and performance of various mechanical components. The propagation of these cracks can take several forms, including straight, curved, and random paths. Most previous studies have mainly focused on straight cracks; however, they often assumed a constant damping ratio in their analytical models. In practice, the damping ratio is likely to change with the crack path, particularly with variations in crack length and orientation, which can reduce the accuracy and reliability of these models. Furthermore, in engineering structures, cracks rarely propagate along idealised straight paths. Instead, they develop along curved or irregular paths. These curved crack paths can significantly alter the patterns of stiffness degradation, the mechanisms of energy dissipation, and the overall dynamic response. Despite their practical importance, the effects of these paths on vibration characteristics remain unexplored. In this thesis, the influence of both straight and curved crack paths on the dynamic response of cantilever fused deposition modelling acrylonitrile butadiene styrene (FDM ABS) and aluminium plate structures was investigated using experimental modal analysis (EMA), finite element analysis (FEA) and machine learning. These substantially different materials were selected to examine whether crack path effects yield consistent trends in vibration response across dissimilar material systems, thereby supporting the broader applicability of the findings. A novel methodology for modelling both straight and curved crack paths was developed. Unlike most previous studies that mainly idealised cracks as straight paths or focused on crack length alone, the novelty of this methodology lies in its ability to systematically model and identify both straight and curved crack paths using dynamic response measurements. The straight cracks are defined using coordinate pairs, while curved cracks are described by second-order polynomial equations. The proposed curved crack modelling scheme reduced the number of possible crack path configurations from 7,140 to 252, corresponding to an approximate 96.5% reduction, while preserving representative geometric diversity for analysis. The effects of crack length and orientation on damping ratio were examined for aluminium and fused deposition modelling (FDM) printed ABS plates. The influence of polynomial coefficients (quadratic, linear, and constant) on the dynamic response of aluminium plates was examined. Finally, both forward and inverse predictive models were developed using linear regression (LR) and artificial neural networks (ANNs) to relate vibration features to crack paths. The results show that crack path has a greater influence on the dynamic response than crack length alone. Numerical results showed that a 50 mm Y-axis crack reduced the first natural frequency to 761.36 rad/s, compared with 771.67 rad/s for a longer 70.71 mm crack oriented at 45°, confirming that crack orientation can dominate over crack length. The same Y-axis crack produced the highest maximum stress and strain, reaching 13.2 MPa and 4.93 × 10⁻⁴, respectively, compared with 8.84 MPa and 3.31 × 10⁻⁴ for the 45° crack and 4.20 MPa and 1.57 × 10⁻⁴ for the X-axis crack. Experimental results further demonstrated that damping ratio increased with crack growth, from approximately 0.0080 to 0.01728 in FDM ABS, representing an increase of about 110%, and from 0.0071 to 0.0117 in aluminium, representing an increase of about 65%. For curved cracks, the quadratic and linear polynomial coefficients had the greatest influence on natural frequency, vibration amplitude, and damping ratio, whereas the constant coefficient had a negligible effect. The proposed prediction models were experimentally validated, with the straight crack polynomial regression model achieving an overall average damping-ratio prediction error of 1.79%. For curved cracks, the forward LR and ANN models predicted natural frequency, amplitude, and damping ratio with an overall average error of 2.28%, while the inverse models estimated final crack path coordinates with an average error of 8.26%. These quantitative findings demonstrate that incorporating crack path geometry improves vibration-based damage assessment and provides a validated framework for crack path identification in plate structures8 0Item Restricted The Views and Experiences of Registered Nurses in Delivering Trauma Care as a Result of the Conflict at the Saudi Southern Border(Queen’s University Belfast, 2024-01) Sadhaan, Abdullah Faisal; Brown, MichaelBackground: Registered Nurses (RNs) provide care and support for patients affected by major traumatic injuries and can be challenged in meeting their physical, cognitive and emotional demands. RNs in trauma care settings are often exposed to threats and fear that affect them personally and professionally. RNs may lack the proper support to meet their emotional needs because of caring for trauma patients. Therefore, it is necessary to gain an understanding of their views and experiences to improve the clinical and personal experiences of trauma RNs serving in the Intensive Care Units (ICU) and Emergency Departments (ED) located in hospitals in the conflict zones along the Saudi-Yemen border. Aim: To identify the views and experiences of RNs providing care for patients requiring trauma care at the Saudi southern border because of the conflict. Methodology: A qualitative method using Thematic analysis (TA) was adopted to gather insights from the respondents. The thematic analysis used a homogeneous purposeful sample from a population of RNs working in the ED and ICU. Semi-structured interviews with 12 RNs were used to collect data while the insights gathered were analysed using the thematic analysis method developed and supported by Braun and Clarke (2006). Findings: The qualitative study established varied views and experiences of the trauma care RNs provide while working in the ED and ICUs. The RNs offered timely trauma care for the injured patients in the conflict zone along Saudi-Yemen border. The findings showed the views and experiences encompassed trauma care provision, education and practice development of RNs, barriers, and solutions to the barriers to the provision of trauma care. The views and experiences of the RNs about trauma care in the ED implied the existence of different models of trauma care. Their role in providing trauma care and the challenges in the ED such as communication barriers, teams or lines of communication, patient advocacy and support, and practice development for the dedicated intensive care operations. The models of trauma care mentioned by the xii respondents were ATLS model of trauma care, Canadian triaging system, and the team- oriented system of delivering trauma care. On the other hand, ED RNs faced challenges of organisation and resourcefulness and inadequate use of international trauma protocol standards. Education and practice development needs of the ED RNs were integral to the experience of delivering quality trauma care. Additionally, the primary barriers included professional, environmental, and organisational obstacles. The RNs described solutions to the barriers such as infrastructural changes, proper education and development, holding debriefing sessions, and development of trauma care teams. The analysis gathered that the ICU RNs had diverse views and experiences on trauma care for the patients from the Saudi-Yemen border. The themes from the analysis included building confidence, gathering or sharing knowledge, and understanding of offering trauma care in the ICU. The themes further include nurse-patient ratio, communication, proper organisation, and resource provision to the trauma RNs. Other findings discovered that the organisation and resource encompassed concerns such as staff shortage, excessive workload, and language barriers. Conversely, the key facilitators of trauma care in the ICU included teams or lines of communication, practice development for the RNs, and support from the hospital management through the equipment, and materials. The major practice and development needs found from the respondents included continuous learning and ATLS-based guidelines. However, the key barriers to trauma care delivery in the ICU include insufficient specialist trauma centres, a high number of trauma patients, and security threats. The ICU RNs proposed solutions such as access to education and practice development, access to the organisational resources, evidence-decision- making, workforce management initiatives, family and patient involvement, protocol and policy development in the ICU. Discussion and Conclusion: The discussion of the key findings was anchored on moral injury theory. The theory denotes the disturbing social, professional, behavioural, and psychological exposures affecting the trauma RNs’ moral beliefs and individual values. The RNs providing trauma care to patients from the conflict zones faced challenges and experiences that deviated from their moral beliefs, particularly within the context of their xiii nursing practice. The suffering at the patient and professional level altered the nurses’ views, social acceptance, connectedness, belonging, trust, and ability to engage with the practice. The study concludes that RNs in the ED and ICUs need additional courses, resources, security, debriefing sessions, incentives to work in the conflict zones. Future studies should use longitudinal designs to identify the effectiveness of overtime pay and hardship allowances in reducing the turnover rates of RNs serving in conflict zones.42 0