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18 pages, 5916 KiB

Open AccessArticle

Analysis and Design of Lateral Framing Systems for Multi-Story Steel Buildings

by Husam Al Dughaishi, Jawad Al Lawati, Moad Alosta, Shaker Mahmood, Mohamed Faisal Al-Kazee, Nur Izzi Md Yusoff and Abdalrhman Milad

Appl. Mech. 2023, 4(2), 389-406; https://doi.org/10.3390/applmech4020022 - 27 Mar 2023

Viewed by 7228

Abstract

This study focused on identifying the most appropriate structural system for multi-story buildings and analyzing its response to lateral loads. The study analyzed and compared the different structural systems to determine the most suitable option. The study aims to utilize three lateral framing [...] Read more.

This study focused on identifying the most appropriate structural system for multi-story buildings and analyzing its response to lateral loads. The study analyzed and compared the different structural systems to determine the most suitable option. The study aims to utilize three lateral framing systems (moment, braced, and diagrid) in order to investigate which system needs the least amount of steel to meet the design requirements. Thus, in order to determine the estimated steel savings of this system as compared to the moment and braced frames, the four-story and eight-story buildings that are 96′ × 96′ in the plane and utilize moment frames, braced frame, and diagrid framing structural systems are presented. Based on the American Society of Civil Engineers (ASCE) 7–10, load combinations are considered for the designs, and the RAM structural analysis is used for the modeling and analysis of the structural systems. The findings of this study’s illustrations were the optimum for the analysis of wind of 176 kips and seismic loads of 122 kips, the building’s lateral displacements, which were the lowest at 0.045 inches, the story drift, the story stiffness, and the story shear for each structural system. In addition, the diagrid system also had the least amount of shear for all the stories, suggesting that it is better able to manage the lateral forces. These results indicate that the diagrid system is a more efficient structural system and can be recommended for use in multi-story buildings. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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22 pages, 3944 KiB

Open AccessArticle

Data-Driven, Physics-Based, or Both: Fatigue Prediction of Structural Adhesive Joints by Artificial Intelligence

by Pedro Henrique Evangelista Fernandes, Giovanni Corsetti Silva, Diogo Berta Pitz, Matteo Schnelle, Katharina Koschek, Christof Nagel and Vinicius Carrillo Beber

Appl. Mech. 2023, 4(1), 334-355; https://doi.org/10.3390/applmech4010019 - 8 Mar 2023

Cited by 12 | Viewed by 3633

Abstract

Here, a comparative investigation of data-driven, physics-based, and hybrid models for the fatigue lifetime prediction of structural adhesive joints in terms of complexity of implementation, sensitivity to data size, and prediction accuracy is presented. Four data-driven models (DDM) are constructed using extremely randomized [...] Read more.

Here, a comparative investigation of data-driven, physics-based, and hybrid models for the fatigue lifetime prediction of structural adhesive joints in terms of complexity of implementation, sensitivity to data size, and prediction accuracy is presented. Four data-driven models (DDM) are constructed using extremely randomized trees (ERT), eXtreme gradient boosting (XGB), LightGBM (LGBM) and histogram-based gradient boosting (HGB). The physics-based model (PBM) relies on the Findley’s critical plane approach. Two hybrid models (HM) were developed by combining data-driven and physics-based approaches obtained from invariant stresses (HM-I) and Findley’s stress (HM-F). A fatigue dataset of 979 data points of four structural adhesives is employed. To assess the sensitivity to data size, the dataset is split into three train/test ratios, namely 70%/30%, 50%/50%, and 30%/70%. Results revealed that DDMs are more accurate, but more sensitive to dataset size compared to the PBM. Among different regressors, the LGBM presented the best performance in terms of accuracy and generalization power. HMs increased the accuracy of predictions, whilst reducing the sensitivity to data size. The HM-I demonstrated that datasets from different sources can be utilized to improve predictions (especially with small datasets). Finally, the HM-I showed the highest accuracy with an improved sensitivity to data size. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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17 pages, 1802 KiB

Open AccessArticle

Closed Form Solution in the Buckling Optimization Problem of Twisted Shafts

by Vladimir Kobelev

Appl. Mech. 2023, 4(1), 317-333; https://doi.org/10.3390/applmech4010018 - 28 Feb 2023

Cited by 1 | Viewed by 1721

Abstract

The counterpart for Euler’s buckling problem is Greenhill’s problem, which studies the forming of a loop in an elastic beam under torsion. In the context of twisted shafts, the optimal shape of the beam along its axis is searched. A priori form of [...] Read more.

The counterpart for Euler’s buckling problem is Greenhill’s problem, which studies the forming of a loop in an elastic beam under torsion. In the context of twisted shafts, the optimal shape of the beam along its axis is searched. A priori form of the cross-section remains unknown. For the solution of the actual problem, the stability equations take into account all possible convex and simply connected shapes of the cross-section. The cross-sections are similar geometric figures related by a homothetic transformation with respect to a homothetic center on the axis of the beam and vary along its axis. The distribution of material along the length of a twisted shaft is optimized so that the beam is of the constant volume and will support the maximal moment without spatial buckling. The applications of the variational method for stability problems are illustrated in this manuscript. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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38 pages, 1825 KiB

Open AccessArticle

On the Countering of Free Vibrations by Forcing: Part II—Damped Oscillations and Decaying Forcing

by Luiz M. B. C. Campos and Manuel J. S. Silva

Appl. Mech. 2023, 4(1), 141-178; https://doi.org/10.3390/applmech4010009 - 31 Jan 2023

Viewed by 2478

Abstract

The present two-part paper concerns the active vibration suppression for the simplest damped continuous system, namely the transverse oscillations of an elastic string, with constant tension and mass density per unit length and friction force proportional to the velocity, described by the telegraph [...] Read more.

The present two-part paper concerns the active vibration suppression for the simplest damped continuous system, namely the transverse oscillations of an elastic string, with constant tension and mass density per unit length and friction force proportional to the velocity, described by the telegraph or wave-diffusion equation, in two complementary parts. The initial part I considers non-resonant and resonant forcing, by concentrated point forces or continuous force distributions independent of time, with phase shift between the forced and free oscillations, in the absence of damping, in which case the forced telegraph equation reduces to the forced classical wave equation. The present and final part II uses the forced wave-diffusion equation to model the effect of damping, both as amplitude decay and phase shift in time, for non-resonant and resonant forcing by a single point force, with constant magnitude or magnitude decaying exponentially in time at an arbitrary rate. Assuming a finite elastic string fixed at both ends, the free oscillations are (i) sinusoidal modes in space-time with exponential decay in time due to damping. The non-resonant forced oscillations at an applied frequency distinct from a natural frequency are also (ii) sinusoidal in space-time, with constant amplitude and a phase shift such that the work of the applied force balances the dissipation. For resonant forcing at an applied frequency equal to a natural frequency, the sinusoidal oscillations in space-time have (iii) a constant amplitude and a phase shift of

π / 2

. In both cases, the (ii) non-resonant or (iii) resonant forcing dominates the decaying free oscillations after some time. Even by optimizing the forcing to minimize the total energy of oscillation, it remains below the energy of the free oscillation alone, but only for a short time—generally a fraction of the period. A more effective method of countering the damped free oscillations is to use forcing with amplitude decaying exponentially in time; by suitable choice of the forcing decay relative to the free damping, the total energy of oscillation over all time can be reduced to no more than

1 / 16

th of the energy of the free oscillation. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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19 pages, 7079 KiB

Open AccessArticle

Structural Analysis of a Composite Passenger Seat for the Case of an Aircraft Emergency Landing

by Georgios Tzanakis, Athanasios Kotzakolios, Efthimis Giannaros and Vassilis Kostopoulos

Appl. Mech. 2023, 4(1), 1-19; https://doi.org/10.3390/applmech4010001 - 28 Dec 2022

Cited by 4 | Viewed by 4601

Abstract

Aviation authorities require, from aircraft seat manufacturers, specific performance metrics that maximize the occupants’ chances of survival in the case of an emergency landing and allow for the safe evacuation of the aircraft cabin. Therefore, aircraft seats must comply with specific requirements with [...] Read more.

Aviation authorities require, from aircraft seat manufacturers, specific performance metrics that maximize the occupants’ chances of survival in the case of an emergency landing and allow for the safe evacuation of the aircraft cabin. Therefore, aircraft seats must comply with specific requirements with respect to their structural integrity and potential occupant injuries, which are certified through the conduction of costly, full-scale tests. To reduce certification costs, computer-aided methods such as finite element analysis can simulate and predict the responses of different seat configuration concepts and potentially save time and development costs. This work presents one of the major steps of an aircraft seat development, which is the design and study of preliminary design concepts, whose structural and biomechanical response will determine whether the concept seat model is approved for the next steps of development. More specifically, a three-occupant aircraft seat configuration is studied for crash landing load cases and is subjected to modification iterations from a baseline design to a composite one for its structural performance, its weight reduction and the reduction of forces transmitted to the passengers. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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33 pages, 2866 KiB

Open AccessArticle

On the Countering of Free Vibrations by Forcing: Part I—Non-Resonant and Resonant Forcing with Phase Shifts

by Luiz M. B. C. Campos and Manuel J. S. Silva

Appl. Mech. 2022, 3(4), 1352-1384; https://doi.org/10.3390/applmech3040078 - 3 Dec 2022

Cited by 1 | Viewed by 2077

Abstract

The question addressed is whether the free oscillations of a continuous system can be suppressed, or at least the total energy reduced, by applying external forces, using as example the linear undamped transverse oscillations of a uniform elastic string. The non-resonant forcing at [...] Read more.

The question addressed is whether the free oscillations of a continuous system can be suppressed, or at least the total energy reduced, by applying external forces, using as example the linear undamped transverse oscillations of a uniform elastic string. The non-resonant forcing at an applied frequency, distinct from all natural frequencies, does not interact with the normal modes, whose energy is unchanged, and adds the energy of the forced oscillation, thus increasing the total energy, that is the opposite of the result being sought. The resonant forcing at an applied frequency, equal to one of the natural frequencies, leads to an amplitude growing linearly with time, and hence the energy is growing quadratically with time, implying an increase in total energy after a sufficiently long time. A reduction in total energy is possible over a short time, say over the first period of oscillation, by optimizing the forcing. In the case of a concentrated force, by optimizing its magnitude and location, the total energy with forcing in one period is reduced by a modest maximum of 2% relative to the free oscillation alone. The conclusion is similar for several concentrated forces. In the case of a continuously distributed force, by optimizing the spatial distribution, it is possible to reduce the energy of the total oscillation to one-fourth of that of the free oscillation over the first period of vibration. This shows that continuously distributed forces are more effective at vibration suppression than point forces. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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16 pages, 3505 KiB

Open AccessArticle

Local Stability in the Process of Excavation Located in High Permeability Saturated Sand of Diaphragm Wall Construction

by Yuhang Liu, Linchun Wei, Yanfei Zhu and Xiaoying Zhuang

Appl. Mech. 2022, 3(4), 1254-1269; https://doi.org/10.3390/applmech3040072 - 31 Oct 2022

Viewed by 1916

Abstract

The stability of the slurry trench is very important in the construction of the underground diaphragm wall. In the current research, the local instability of the slurry trench is mainly investigated after the excavation of a unit slot is completely completed. However, the [...] Read more.

The stability of the slurry trench is very important in the construction of the underground diaphragm wall. In the current research, the local instability of the slurry trench is mainly investigated after the excavation of a unit slot is completely completed. However, the local stability in the process of excavation has received little attention. In this paper, the local stability in the process of excavation located in high permeability strata of diaphragm wall construction is investigated. A slurry infiltration experiment was carried out to investigate the distribution of the excess pore pressure in the high permeability strata, which can determine the effective support pressure. Then, the local stability of the slurry trench in the process of excavation located in high permeability saturated sand is calculated. The results show that the same types of sand according to the design code cannot be simply treated to have the same permeability and similar distribution of the excess pore pressure, since whether the filter cake can be formed and the quality of the filter cake are the key factors to determine the distribution of the excess pore pressure. This is also crucial for the local stability in the process of excavation located in high permeability saturated sand. It is suggested that attention should be paid to the local stability in the process of excavation located in high permeability strata when the slurry infiltration mode is the pure permeable zone. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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14 pages, 38912 KiB

Open AccessArticle

Design and Fabrication of Untethered Light-Actuated Microbots in Fluid for Biomedical Applications

by Md Faiyaz Jamil, Mishal Pokharel and Kihan Park

Appl. Mech. 2022, 3(4), 1240-1253; https://doi.org/10.3390/applmech3040071 - 17 Oct 2022

Cited by 3 | Viewed by 2364

Abstract

Untethered mobile robots at the micro-scale have the ability to improve biomedical research by performing specialized tasks inside complex physiological environments. Light-controlled wireless microbots are becoming the center of interest thanks to their accuracy in navigation and potential to carry out operations in [...] Read more.

Untethered mobile robots at the micro-scale have the ability to improve biomedical research by performing specialized tasks inside complex physiological environments. Light-controlled wireless microbots are becoming the center of interest thanks to their accuracy in navigation and potential to carry out operations in a non-invasive manner inside living environments. The pioneering light-engineered microbots are currently in the early stage of animal trials. There is a long way ahead before they can be employed in humans for therapeutic applications such as targeted drug delivery, cancer cell diagnosis, tissue engineering, etc. The design of light-actuated microbots is one of the challenging parts along with the biocompatibility and precision control for in vivo applications. Recent progress in light-activated microbots has revealed a few innovative design concepts. In this study, we presented a framework on the different aspects with a comparative analysis of potential designs for the next generation of light-controlled microbots. Utilizing numerical simulations of fluid-structure interactions, limiting design elements of the microbots are addressed. We envision that this study will eventually facilitate the integration of robotic applications into the real world owing to the described design considerations. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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17 pages, 5446 KiB

Open AccessArticle

A Novel Technique for Temporarily Repair and Improvement of Damaged Pin Joint Support Bores

by Øyvind Karlsen, Hirpa G. Lemu and Imad Berkani

Appl. Mech. 2022, 3(4), 1206-1222; https://doi.org/10.3390/applmech3040069 - 6 Oct 2022

Viewed by 2677

Abstract

Damaged support bores due to wear and ovality can be critical for a machine and its operation, in addition to representing a safety problem and risk of pin breakage. It can be a costly operation to perform the required repairs in between planned [...] Read more.

Damaged support bores due to wear and ovality can be critical for a machine and its operation, in addition to representing a safety problem and risk of pin breakage. It can be a costly operation to perform the required repairs in between planned service periods, especially because of the unplanned down time. A joint with a standard cylindrical pin will often experience wear and ovality in the support bore surfaces, and at some point, repairs will have to be performed. This study investigates and compares five options when a joint with a cylindrical pin has reached a severe level of wear and ovality, outside its planned service stop. The work involved testing the viability of 3D scanning of the damaged bore surface, 3D printing of a metal bushing, and inserting the bushing into the damaged joint. In addition, two pin solutions, i.e., a standard cylindrical pin and an expanding pin type, were installed into the repaired joint, loaded, and the strain on the pin ends close to the supports was measured. For the sake of comparison, the supports had both smooth circular bore and severe wear and ovality. It was concluded that it is possible to produce and install the 3D-printed bushing insert without major problems; the insert had satisfactory capability during test loading, and it most probably represents a good solution when it comes to the reduction in unwanted downtime during unplanned repairs of damaged joints. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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14 pages, 4114 KiB

Open AccessArticle

Multidisciplinary Design Optimization of a Re-Entry Spacecraft via Radau Pseudospectral Method

by Masoud Kabganian, Seyed M. Hashemi and Jafar Roshanian

Appl. Mech. 2022, 3(4), 1176-1189; https://doi.org/10.3390/applmech3040067 - 26 Sep 2022

Cited by 1 | Viewed by 2300

Abstract

The design and optimization of re-entry spacecraft or its subsystems is a multidisciplinary or multiobjective optimization problem by nature. Multidisciplinary design optimization (MDO) focuses on using numerical optimization in designing systems with several subsystems or disciplines that have interactions and independent actions. In [...] Read more.

The design and optimization of re-entry spacecraft or its subsystems is a multidisciplinary or multiobjective optimization problem by nature. Multidisciplinary design optimization (MDO) focuses on using numerical optimization in designing systems with several subsystems or disciplines that have interactions and independent actions. In the present paper, the system-level optimizer, trajectory, geometry and shape, aerodynamics, and aerothermodynamics differential equations, are converted to algebraic equations using the Radau pseudospectral method (RPM) since a spacecraft is a nonlinear, extensive, and sparse system. The solution to the problem with the help of MDO is reached by iterating all the disciplines together; one can simultaneously enhance the design, decrease the time and cost of the entire design cycle, and minimize the structural mass of a re-entry spacecraft. Considering various methods presented in earlier research works, a combined and innovative all-at-once (AAO), RPM-based MDO method, including the key subsystems in the design process of a re-entry capsule-shape spacecraft with a low lift-to-drag ratio (L/D), is presented. Considering the applicable state and control variables, various constraints, and parameters applied to several geometric shapes of a blunt capsule and using Apollo’s aerodynamic and aerothermodynamic coefficients, the optimized dimensions for a re-entry spacecraft are presented. The introduced optimization scheme led to a 17% mass reduction compared to the original mass of the Apollo vehicle. Fast computing and simplified models are used together in this method to analyze a wide range of vehicle shapes and entry types during conceptual design. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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18 pages, 7495 KiB

Open AccessArticle

Al-RHEA Particulates MMCs by PM Route: Mechanical Properties and Sliding Wear Response

by Elias Anastasios Ananiadis, Alexander Efstathios Karantzalis, Dimitrios A. Exarchos and Theodore E. Matikas

Appl. Mech. 2022, 3(3), 1145-1162; https://doi.org/10.3390/applmech3030065 - 15 Sep 2022

Cited by 5 | Viewed by 1992

Abstract

New particle reinforced aluminum matrix composites with the addition of refractory High Entropy Alloy, MoTaNbVW, fabricated via powder metallurgy process were assessed for their properties. Basic mechanical properties (modulus of elasticity, hardness) for the aluminum matrix, the pure aluminum and the reinforcement phase [...] Read more.

New particle reinforced aluminum matrix composites with the addition of refractory High Entropy Alloy, MoTaNbVW, fabricated via powder metallurgy process were assessed for their properties. Basic mechanical properties (modulus of elasticity, hardness) for the aluminum matrix, the pure aluminum and the reinforcement phase were assessed by means of dynamic nano-indentation technique. Nano-indentation based creep response was also evaluated in these three areas of interest. Hardness shows an increase with the addition of the particulates and so does the elastic moduli and the ratio of the energy absorbed in the elastic region. The creep response was approached in terms of dislocation mobility and critical volume for their nucleation. The produced Al–HEA composites were also studied for their sliding wear behavior and showed that with the increase in percentage of RHEA particulates the wear resistance increases. Microstructural considerations, wear track morphologies, and debris characteristics were used for the assessment of the involved wear mechanisms. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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22 pages, 34189 KiB

Open AccessArticle

Aerodynamic Shape Optimization of an Aircraft Propulsor Air Intake with Boundary Layer Ingestion

by Ayesh Sudasinghe, Padmassun Rajakareyar, Edgar Matida, Hamza Abo El Ella and Mostafa S. A. ElSayed

Appl. Mech. 2022, 3(3), 1123-1144; https://doi.org/10.3390/applmech3030064 - 12 Sep 2022

Cited by 4 | Viewed by 3430

Abstract

The growth of the airline industry has highlighted the need for more environmentally conscious aviation, leading to the conceptualization of more fuel-efficient aircraft. One concept that has received significant attention and has been associated with improved fuel efficiency is the boundary layer ingesting [...] Read more.

The growth of the airline industry has highlighted the need for more environmentally conscious aviation, leading to the conceptualization of more fuel-efficient aircraft. One concept that has received significant attention and has been associated with improved fuel efficiency is the boundary layer ingesting (BLI) propulsion system, which refers to the ingesting of the aircraft wake by the propulsors. Although BLI has theoretically been proven to reduce fuel burn, this can potentially be offset by the reduced efficiency and stability experienced by the propulsor in the presence of distorted inflow. Therefore, engine intakes must be optimized in order to mitigate the effects of BLI on the propulsion system. In this work, the shape optimization of a BLI intake is investigated using a free-form deformation technique in combination with a multi-objective genetic algorithm, in order to minimize pressure losses and distortion at the engine inlet. The optimization is performed on an S-duct intake at a cruise altitude of approximately 37,000 feet and a free stream Mach number of 0.7. An optimization strategy was developed for the task which was able to produce a Pareto optimal set of designs with improved pressure recovery and distortion. The general trend of the optimal designs shows that to reduce distortion the optimizer accelerates the flow to reduce the size of the low total pressure region and increase the dynamic pressure at the engine inlet. In contrast, the pressure recovery was increased by reducing velocity as well as shifting the maximum velocity region to the outlet, which reduces the viscous dissipation losses within the intake. The final result is a fully autonomous optimization strategy resulting in reduced pressure losses and reduced distortion leading to higher efficiency BLI S-duct intake designs. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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16 pages, 4832 KiB

Open AccessArticle

On Computational Asymptotic Analysis of General Sensitive Shells of Revolution

by Harri Hakula

Appl. Mech. 2022, 3(3), 1091-1106; https://doi.org/10.3390/applmech3030062 - 29 Aug 2022

Cited by 5 | Viewed by 1878

Abstract

Recent advances in drug delivery technology have led to renewed interest in shell structures with mixed kinematical constraints, one end clamped, another one free, the so-called sensitive shells. It is known that elliptic sensitive shell problems may not always satisfy the Shapiro–Lopatinsky conditions [...] Read more.

Recent advances in drug delivery technology have led to renewed interest in shell structures with mixed kinematical constraints, one end clamped, another one free, the so-called sensitive shells. It is known that elliptic sensitive shell problems may not always satisfy the Shapiro–Lopatinsky conditions and hence are not necessarily well-posed. The new observation is that for shells of revolution if the profile function has regions of elliptic Gaussian curvature, that region will dictate the overall response of the structure under concentrated loading. Despite the monotonically increasing total energy as the thickness tends asymptotically to zero, these shells are not in a pure bending state. The numerical results have been verified using equivalent lower-dimensional solutions. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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17 pages, 3919 KiB

Open AccessArticle

Bending Stresses and Deformations in Prismatic Profiled Shafts with Noncircular Contours Based on Higher Hybrid Trochoids

by Masoud Ziaei

Appl. Mech. 2022, 3(3), 1063-1079; https://doi.org/10.3390/applmech3030060 - 23 Aug 2022

Cited by 5 | Viewed by 2234

Abstract

This paper presents an analytical method for determining the bending stresses and deformations in prismatic, noncircular profile shafts with trochoidal cross sections. The so-called higher trochoids can be used as form-fit shaft-hub connections. Hybrid (mixed) higher trochoids (M-profiles) were developed for the special [...] Read more.

This paper presents an analytical method for determining the bending stresses and deformations in prismatic, noncircular profile shafts with trochoidal cross sections. The so-called higher trochoids can be used as form-fit shaft-hub connections. Hybrid (mixed) higher trochoids (M-profiles) were developed for the special application as a profile contour for the form-fit shaft and hub connections in an earlier work by the author. M-profiles combine the advantages of the two standardised polygonal and spline contours, which are used as shaft-hub connections for the transmission of high torques. In this study, the geometric and mechanical properties of the higher hybrid trochoids were investigated using complex functions to simplify the calculations. The pure bending stress and shaft deflection were determined for M-profiles using bending theory based on the theory of mathematical elasticity. The loading cases consisted of static and rotating bends. Analytical, numerical, and experimental results agreed well. The calculation formulas developed in this work enable reliable and low-cost dimensioning with regard to the stresses and elastic deformations of profile shafts subjected to bending loads. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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16 pages, 778 KiB

Open AccessArticle

A New Algorithm to Solve the Extended-Oxley Analytical Model of Orthogonal Metal Cutting in Python

by Olivier Pantalé, Maxime Dawoua Kaoutoing and Raymond Houé Ngouna

Appl. Mech. 2022, 3(3), 889-904; https://doi.org/10.3390/applmech3030051 - 14 Jul 2022

Viewed by 2750

Abstract

This paper presents a new implementation method of the Extended-Oxley analytical model, previously proposed by Lalwani in 2009, for orthogonal cutting of metals with a Johnson–Cook thermo-elastoplastic flow law. The present work aims to improve the implementation of this analytical model in order [...] Read more.

This paper presents a new implementation method of the Extended-Oxley analytical model, previously proposed by Lalwani in 2009, for orthogonal cutting of metals with a Johnson–Cook thermo-elastoplastic flow law. The present work aims to improve the implementation of this analytical model in order to propose a unified solution that overcomes the main shortcomings of the original model: the non-uniqueness of the solution, the low accuracy of the obtained solution, and the relatively long computational time for a purely analytical approach. In the proposed implementation, the determination of the optimal set of model parameters is based on an optimization method using the Python LMFIT library with which we have developed a dual Levenberg–Marquardt optimization algorithm. In this paper, the performance and efficiency of the developed model are presented by comparing our results for a 1045 steel with the simulation results obtained in the original paper proposed by Lalwani. The comparison shows a considerable gain in terms of computational speed (more than 2000 times faster than the original model), uniqueness of the obtained solution, and accuracy of the obtained numerical solution (almost zero force imbalance). Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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34 pages, 4761 KiB

Open AccessArticle

Non-Linear Model of Predictive Control-Based Slip Control ABS Including Tyre Tread Thermal Dynamics

by Vincenzo Maria Arricale, Andrea Genovese, Abhishek Singh Tomar, Karel Kural and Aleksandr Sakhnevych

Appl. Mech. 2022, 3(3), 855-888; https://doi.org/10.3390/applmech3030050 - 6 Jul 2022

Cited by 8 | Viewed by 3518

Abstract

Vehicle dynamics can be deeply affected by various tyre operating conditions, including thermodynamic and wear effects. Indeed, tyre temperature plays a fundamental role in high performance applications due to the dependencies of the cornering stiffness and potential grip in such conditions. This work [...] Read more.

Vehicle dynamics can be deeply affected by various tyre operating conditions, including thermodynamic and wear effects. Indeed, tyre temperature plays a fundamental role in high performance applications due to the dependencies of the cornering stiffness and potential grip in such conditions. This work is focused on the evaluation of a potentially improved control strategy’s performance when the control model is fed by instantaneously varying tyre parameters, taking into account the continuously evolving external surface temperature and the vehicle boundary conditions. To this end, a simplified tyre thermal model has been integrated into a model predictive control strategy in order to exploit the thermal dynamics’ dependents within a proposed advanced ABS control system. We evaluate its performance in terms of the resulting braking distance. In particular, a non-linear model predictive control (NMPC) based ABS controller with tyre thermal knowledge has been integrated. The chosen topic can possibly lay a foundation for future research into autonomous control where the detailing of decision-making of the controllers will reach the level of multi-physical phenomena concerning the tyre–road interaction. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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19 pages, 16785 KiB

Open AccessArticle

Waterproof Design of Soft Multi-Directional Force Sensor for Underwater Robotic Applications

by Liam B. Cross, Rafsan Al Shafatul Islam Subad, Md Mahmud Hasan Saikot and Kihan Park

Appl. Mech. 2022, 3(3), 705-723; https://doi.org/10.3390/applmech3030042 - 22 Jun 2022

Cited by 4 | Viewed by 3319

Abstract

Directional force sensing is an intrinsic feature of tactile sensing. As technologies of exploratory robots evolve, with special emphasis on the emergence of soft robotics, it is crucial to equip robotic end-effectors with effective means of characterizing trends in force detection and grasping [...] Read more.

Directional force sensing is an intrinsic feature of tactile sensing. As technologies of exploratory robots evolve, with special emphasis on the emergence of soft robotics, it is crucial to equip robotic end-effectors with effective means of characterizing trends in force detection and grasping phenomena, while these trends are largely derived from networks of tactile sensors working together, individual sensors must be built to meet an intended function and maintain functionality with respect to environmental operating conditions. The harshness of underwater exploration imposes a unique set of circumstances onto the design of tactile sensors. When exposed to underwater conditions a tactile sensor must be able to withstand the effects of increased pressure paired with water intrusion while maintaining computational and mechanical integrity. Robotic systems designed for the underwater environment often become expensive and cumbersome. This paper presents the design, fabrication, and performance of a low-cost, soft-material sensor capable of multi-directional force detection. The fundamental design consists of four piezo-resistive flex elements offset at 90

^{\circ}

increments and encased inside of a hemispherical silicone membrane filled with a non-compressive and non-conductive fluid. The sensor is simulated numerically to characterize soft-material deformation and is experimentally interrogated with indentation equipment to investigate sensor-data patterns when subject to different contact forces. Furthermore, the sensor is subject to a cyclic loading test to analyze the effects of hysteresis in the silicone and is submerged underwater for a 7-day period to investigate any effect of water intrusion at a shallow depth. The outcome of this paper is the proposed design of a waterproofed, soft-material tactile sensor capable of directional force detection and contact force localization. The overall goal is to widen the scope of tactile sensor concepts outfitted for the underwater environment. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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9 pages, 2258 KiB

Open AccessArticle

Analytical Solution of Oscillatory Stokes Flow in a Porous Pipe with Spatiotemporally Periodic Suction/Injection

by Christos Manopoulos, Anastasios Raptis and Sokrates Tsangaris

Appl. Mech. 2022, 3(2), 683-691; https://doi.org/10.3390/applmech3020040 - 18 Jun 2022

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Abstract

The study presents a generalized analytical solution of the laminar, oscillatory, creeping flow of an incompressible Newtonian fluid in a porous circular pipe with spatiotemporally periodic suction/injection at the wall. The analytical solution is examined for a variety of values of the dimensionless [...] Read more.

The study presents a generalized analytical solution of the laminar, oscillatory, creeping flow of an incompressible Newtonian fluid in a porous circular pipe with spatiotemporally periodic suction/injection at the wall. The analytical solution is examined for a variety of values of the dimensionless parameters, namely the Womersley number and the dimensionless suction/injection number. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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A Survey on Non-Destructive Smart Inspection of Wind Turbine Blades Based on Industry 4.0 Strategy

by Mariya Dimitrova, Ahmad Aminzadeh, Mohammad Saleh Meiabadi, Sasan Sattarpanah Karganroudi, Hossein Taheri and Hussein Ibrahim

Appl. Mech. 2022, 3(4), 1299-1326; https://doi.org/10.3390/applmech3040075 - 16 Nov 2022

Cited by 15 | Viewed by 7687

Abstract

Wind turbines are known to be the most efficient method of green energy production, and wind turbine blades (WTBs) are known as a key component of the wind turbine system, with a major influence on the efficiency of the entire system. Wind turbine [...] Read more.

Wind turbines are known to be the most efficient method of green energy production, and wind turbine blades (WTBs) are known as a key component of the wind turbine system, with a major influence on the efficiency of the entire system. Wind turbine blades have a quite manual production process of composite materials, which induces various types of defects in the blade. Blades are susceptible to the damage developed by complex and irregular loading or even catastrophic collapse and are expensive to maintain. Failure or damage to wind turbine blades not only decreases the lifespan, efficiency, and fault diagnosis capability but also increases safety hazards and maintenance costs. Hence, non-destructive testing (NDT) methods providing surface and subsurface information for the blade are indispensable in the maintenance of wind turbines. Damage detection is a critical part of the inspection methods for failure prevention, maintenance planning, and the sustainability of wind turbine operation. Industry 4.0 technologies provide a framework for deploying smart inspection, one of the key requirements for sustainable wind energy production. The wind energy industry is about to undergo a significant revolution due to the integration of the physical and virtual worlds driven by Industry 4.0. This paper aims to highlight the potential of Industry 4.0 to help exploit smart inspections for sustainable wind energy production. This study is also elaborated by damage categorization and a thorough review of the state-of-the-art non-destructive techniques for surface and sub-surface inspection of wind turbine blades. Full article

(This article belongs to the Special Issue Feature Papers in Applied Mechanics)

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