Thermo-mechanical fatigue life and probabilistic fracture assessment of a large-bore diesel engine block using integrated S-N, SMART technology, and non-linear regression models Ardeshir Savari, Khaled Alnefaie Results in Engineering, 2026 • Integrated S-N and LEFM crack‑growth modelling via SMART tool. • Combustion pressure identified as primary fracture‑risk driver. • Combustion temperature rise 400-800 °C reduces fatigue SF by 39 %. • Cylinder diameter increase 30-198 mm lowers fatigue SF from 3.5 to 0.3. • Monte-Carlo analysis shows cracked-life P f >0.13, dominating failure risk. Large-bore, high-cylinder-count diesel engine blocks are subject to severe cyclic thermos-mechanical loading; however, fracture-based fatigue assessments of such complex structures are scarce. In this study, an integrated deterministic–probabilistic framework is developed to evaluate the thermo-mechanical fatigue life of a 20V MTU engine block, combining classical stress-life modelling with crack-growth analysis. This is achieved using the Separating Morphing and Adaptive Remeshing Technology (SMART) framework within a sequentially coupled finite-element framework. This hybrid strategy enables direct simulation of crack initiation and propagation under realistic combustion-induced pressure and temperature gradients, which eliminates the need for manual remeshing. Non-linear regression and sensitivity analyses quantify the influence of geometric, thermal, and loading parameters on static and fatigue safety factors. Statistical analysis based on Spearman’s rank correlation coefficient indicates that combustion pressure is the most influential variable, followed by stress ratio and flaw size. A Monte-Carlo-based structural reliability analysis is also incorporated to capture variability across static, fatigue, and cracked-life limit states. The results highlight that cracked-life is the dominant contributor to total failure probability, and that a combustion temperature rise from 400°C to 800°C reduces the fatigue safety factor by 39%. Enlarging the cylinder diameter from 30 mm to 198 mm decreases this quantity from 3.5 to 0.3. The proposed probabilistic methodology offers a novel approach for predicting fracture-critical durability in large engine blocks under coupled thermo-mechanical service conditions
Meso-macro damage modelling of corrugated FRP tubes under multiaxial loads: Design‑driven cohesive delamination and probabilistic reliability Ardeshir Savari, Khaled A. Alnefaie, Narinderjit Singh Sawaran Singh Materials Today Communications, 2026 Reliable design of corrugated fibre‑reinforced polymer (FRP) tubes requires explicit consideration of mesoscale damage mechanisms and their probabilistic interaction under multiaxial loading. This study develops a three‑dimensional finite‑element framework that integrates a bilinear cohesive‑zone model with Puck’s action‑plane failure criterion to capture delamination, intralaminar cracking, and stiffness degradation across multilayer laminate architectures. A structured design‑of‑experiments strategy is employed to evaluate the influence of adhesive properties, loading paths, and laminate configuration, including fibre orientation, ply count, ply thickness, and transverse modulus. Nonlinear surrogate limit‑state functions extracted from the simulations enable generalised Puck‑based safety factors for combined loading conditions. Monte Carlo reliability analysis reveals a four‑order‑of‑magnitude reduction in failure probability under tensile loading as the safety margin increases from 0.9 to 1.4, whereas compressive loading remains reliability‑limited due to the inherent compression sensitivity of multilayer laminates. The results demonstrate that deterministic stiffness and strength enhancements alone do not guarantee structural integrity. The proposed formulations provide quantitative guidance for the probabilistic design of corrugated FRP tubes under multiaxial loads, supporting resilient infrastructures in pipeline and aerospace applications. • Puck-CZM framework details intralaminar-interlaminar failure cascade. • Non-monotonic reliability sensitivity to E 2 n and G Ic is identified. • Compressive failure is limited by displacement more than material strength. • Compressive mode shows persistent reliability concerns under multiaxial loading. • Tensile P f drops 4 orders of magnitude but compressive P f saturates high.
Enhancement of Wind Turbine Vibrational Behavior by using a Pendulum Tuned Mass Damper Waleed Dirbas, Hamza Diken, Khalid Alnefaie Engineering Technology and Applied Science Research, 2025 Wind turbines experience significant vibrations due to fluctuating wind loads, which can impact structural integrity and operational efficiency. This study examines the effectiveness of Pendulum Tuned Mass Dampers (PTMDs) for mitigating these vibrations. Two types of wind force inputs were analyzed: a sinusoidal function representing periodic wind fluctuations and a random function simulating turbulent wind effects. Numerical simulations were conducted to evaluate the influence of mass ratios (0.01, 0.02, and 0.05) and damping ratios (0.1, 0.02, and 0.05) on vibration suppression. The results indicate that the installation of a PTMD can reduce vibrations from 45% to 91% under varying operating conditions. The optimum vibration suppression of up to 91% was achieved when the damping ratio was 0.02 and the mass ratio was 0.01 under sinusoidal wind force excitation. A mass ratio of 0.05 also led to a decrease of 54% in nacelle oscillations, confirming the effectiveness of PTMD in promoting stability. An optimal damping ratio of 0.02 was found to effectively balance energy dissipation and structural stability, preventing excessive oscillations and maintaining system efficiency. These findings confirm that integrating a PTMD can enhance wind turbine performance by reducing fatigue loads and extending operational lifespan. By optimizing the PTMD parameters, engineers can achieve better vibration control, improving the stability and durability of wind turbines under varying wind conditions. This study underscores the importance of passive vibration control mechanisms in modern wind energy systems and provides valuable insights into enhancing their long-term reliability.
The Effect of Tuned Mass Damper Mass Ratio on Wind Turbine Vibration Mitigation Waleed Dirbas, Hamza Diken, Khalid Alnefaie Engineering Technology and Applied Science Research, 2024 This paper examines the efficacy of Tuned Mass Dampers (TMDs) in mitigating vibration in wind turbines under diverse excitation force conditions. The impact of TMD on the response of a wind turbine exposed to sinusoidal and random wind forces, at varying mass ratios μm: 0.02, 0.05, 0.10, and 0.20, was assessed through the use of a MATLAB SIMULINK model. The findings indicate that TMDs markedly attenuate vibration when subjected to sinusoidal forces, particularly at higher TMD mass ratios. In contrast, the reduction in vibration level in the presence of random wind forces is relatively modest, becoming more pronounced at higher TMD mass ratios. In addition, the internal forces generated by incorporating the TMD into the system were calculated for different mass ratio values. It was noted that these forces increased in proportion to the mass ratio, although they remained within reasonable limits. However, an increase in the TMD mass ratio has been observed to result in a corresponding increase in these forces. This underscores the importance of meticulous mass ratio selection for the optimal functioning of TMD systems. It suggests that dealing with complex, broadband excitation may entail inherent limitations. The findings of this study may prove valuable in enhancing the understanding of the stability and lifetime of wind turbines under dynamic wind conditions.
Gradient and mechanical properties of carbon nanotube-reinforced epoxy-composites: Experimental study and theoretical analysis 2014 the 4th International Workshop on Computer Science and Engineering Winter Wcse 2014, 2014
