236 research outputs found

    Interlaminar Response of LSI-Produced C/SiC Ceramic Matrix Composites: Experiments and Modelling

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    This work investigates the interlaminar properties of a C/SiC composite produced by Liquid Silicon Infiltration, combining experiments based on Double Cantilever Beam tests and numerical analyses. Experimentally, a method to obtain pre-cracks with sharp tips at precise locations is proposed, and specimens with different thickness are used to investigate the effects of bending stress states in the delamination process. The properties of tri-linear Cohesive Zone Models for the modelling of delamination are identified numerically, by using automatic regression techniques without requiring additional assumptions or testing. Fiber bridging effects were observed and modelled, including the evaluation of the process zone lengths with different experimental, analytical, and numerical methods. Overall, the work provides a qualitative insight in the delamination process of long fiber reinforced C/SiC laminates produced with a cost-affordable technique and proposes an experimental and numerical protocol to characterize and model delamination phenomena, taking into account the scattering of material properties

    Dynamic Behavior Analysis of a Rotating Shaft with an Elliptical Breathing Surface Crack

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    Open access via the Springer Compact Acknowledgements The authors would like to thank the anonymous reviewers for their valuable suggestions that helped in improving the manuscript.Peer reviewedPublisher PD

    The evaluation of workers satisfaction on usability of manual handling equipment among warehouse workers in Malaysia

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    Numerous researchers have found that heavy physical demand and improper posture when performing the tasks in various sectors such as manufacturing and warehouse might contribute to the musculoskeletal disorders (MSDs) especially when the tasks involving lifting, pushing and pulling activities. In order to reduce high risk manual handling activities, effectives and usable manual handling equipment (MHE) should be introduce to lower the physical demand of manual material handling (MMH) acti�vities. However, most of the MHE studies previously is not really focus on usability evaluation. So, this study intends to evaluate the usability of current MHE used in manufacturing warehouse operation in term of efficiency, comfortability, energy expenditure, safety aspect, design, productivity, effectiveness and user friendliness. A usability survey was conducted among warehouse workers in manufacturing com�pany at southern region of peninsular Malaysia. Besides that, the prevalence of backpain among the warehouse workers was measured through Modified Nordic Discomfort Assessment tools that are incorporate in the usability survey. Result for the most least agreement in user usability for pallet jack was energy expenditure (3.73), efficiency (3.96) and comfortability (3.99); for load carrying cart was energy expen�diture (3.62), design (3.74) and comfortability (3.90); for forklift was comfortability (3.87), design (3.93) and safety (4.08); for pallet stackers was energy expenditure (3.79), design (3.82) and user friendliness (3.82); for conveyor system was productivity (3.50), comfortability (4.00) and safety (4.00). It was also found that the highest prevalence of MSDs among warehouse workers was lower back, followed by legs (left and right) and shoulders (left and right). In conclusion, most MHE available in manufacturing warehouse operation lacking in term of energy expenditure, efficiency, comfortability, design and user friendliness. It is clear that the first stage in design criteria for MHE should be developing an understanding of the user usability requirement to ensure the aids are suitable for the tasks

    Applications of Finite Element Modeling for Mechanical and Mechatronic Systems

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    Modern engineering practice requires advanced numerical modeling because, among other things, it reduces the costs associated with prototyping or predicting the occurrence of potentially dangerous situations during operation in certain defined conditions. Thus far, different methods have been used to implement the real structure into the numerical version. The most popular uses have been variations of the finite element method (FEM). The aim of this Special Issue has been to familiarize the reader with the latest applications of the FEM for the modeling and analysis of diverse mechanical problems. Authors are encouraged to provide a concise description of the specific application or a potential application of the Special Issue

    Feature Papers in Electronic Materials Section

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    This book entitled "Feature Papers in Electronic Materials Section" is a collection of selected papers recently published on the journal Materials, focusing on the latest advances in electronic materials and devices in different fields (e.g., power- and high-frequency electronics, optoelectronic devices, detectors, etc.). In the first part of the book, many articles are dedicated to wide band gap semiconductors (e.g., SiC, GaN, Ga2O3, diamond), focusing on the current relevant materials and devices technology issues. The second part of the book is a miscellaneous of other electronics materials for various applications, including two-dimensional materials for optoelectronic and high-frequency devices. Finally, some recent advances in materials and flexible sensors for bioelectronics and medical applications are presented at the end of the book

    AIMETA 2005. Atti del XVII Congresso dell'Associazione italiana di meccanica teorica e applicata. Firenze, 11-15 settembre 2005

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    The volume collects the contributions presented at the XVII national congress of AIMETA. The contributions are grouped according to the various sectors of theoretical and applied mechanics and are offered by a vast scientific community. In addition to the classical sectors, themes of interdisciplinary significance and of considerable interest and highly innovative content were added, for the analysis of which small exchange symposia were proposed. Organised according to 52 sessions (plenary and parallel), the volume contains 290 scientific works that are mainly the result of international cooperation. Therefore, the work represents a significant picture of the current situation and future prospects for mechanics

    Beam-like damage detection methodology using wavelet damage ratio and additional roving mass

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    Early damage detection plays an essential role in the safe and satisfactory maintenance of structures. This work investigates techniques use only damaged structure responses. A Timoshenko beam was modeled in finite element method, and an additional mass was applied along their length. Thus, a frequency-shift curve is observed, and different damage identification techniques were used, such as the discrete wavelet transform and the derivatives of the frequency-shift curve. A new index called wavelet damage ratio(WDR) is defined as a metric to measure the damage levels. Damages were simulated like a mass discontinuity and a rotational spring (stiffness damage). Both models were compared to experimental tests since the mass added to the structure is a non-destructive tool. It was evaluated different damage levels and positions. Numerical results showed that all proposed techniques are efficient techniques for damage identification in Timoshenko's beams concerning low computational cost and practical application

    The Application of PSO in Structural Damage Detection: An Analysis of the Previously Released Publications (2005–2020)

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    The structural health monitoring (SHM) approach plays a key role not only in structural engineering but also in other various engineering disciplines by evaluating the safety and performance monitoring of the structures. The structural damage detection methods could be regarded as the core of SHM strategies. That is because the early detection of the damages and measures to be taken to repair and replace the damaged members with healthy ones could lead to economic advantages and would prevent human disasters. The optimization-based methods are one of the most popular techniques for damage detection. Using these methods, an objective function is minimized by an optimization algorithm during an iterative procedure. The performance of optimization algorithms has a significant impact on the accuracy of damage identification methodology. Hence, a wide variety of algorithms are employed to address optimization-based damage detection problems. Among different algorithms, the particle swarm optimization (PSO) approach has been of the most popular ones. PSO was initially proposed by Kennedy and Eberhart in 1995, and different variants were developed to improve its performance. This work investigates the objectives, methodologies, and results obtained by over 50 studies (2005-2020) in the context of the structural damage detection using PSO and its variants. Then, several important open research questions are highlighted. The paper also provides insights on the frequently used methodologies based on PSO, the computational time, and the accuracy of the existing methodologies
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