Reinforcing Bus Living Space with Recycled Carbon Fibers from Expired Prepreg in the Aircraft Industry
Due to increasing mobility and energy conservation needs, improving bus and coach safety without adding weight is essential. Many crashes with fatal outcomes for vehicle occupants are associated with the rollover of the vehicle, revealing the structural weakness of the steel pillars between windows, which must resist high levels of bending during rollovers. This study aims to reinforce these pillars with expired carbon fiber prepreg from the aircraft industry, improving safety and reducing environmental waste. To manufacture the pillars, shot-blasted hollow S275 steel tubes with a side length of 25 mm and a thickness of 1.5 mm were used. Bidirectional GG600T woven carbon fiber, CF, and aircraft-grade recycled carbon fiber-reinforced plastic, rCFRP, prepreg M21EV/IMA/3 were used as composite reinforcements. The first composite was made from a CF weave using the rigid epoxy resin Sicomin® 8500/Sicomin® SD8601. The rCFRP composite was frayed, and a new composite was made with the same rigid epoxy resin. Both composites were joined to the steel tube using a tough structural adhesive (SikaPower® 1277). A third composite was obtained using the frayed rCFRP and the structural adhesive as a polymer matrix. All composites were treated with an APPT (atmospheric-pressure plasma torch) before being joined to the steel pillar with the structural adhesive. The comparison of the three reinforcements showed that the steel reinforced with the recycled prepreg composite manufactured with the rigid adhesive performed best, with a 50% increase in specific bending strength and only a 32% increase in weight. It also absorbed 71% more energy, which shows that this novel option for upcycling can noticeably increase the crashworthiness of structures.
Año de publicación: 2024
Due to increasing mobility and energy conservation needs, improving bus and coach safety without adding weight is essential. Many crashes with fatal outcomes for vehicle occupants are associated with the rollover of the vehicle, revealing the structural weakness of the steel pillars between windows, which must resist high levels of bending during rollovers. This study aims to reinforce these pillars with expired carbon fiber prepreg from the aircraft industry, improving safety and reducing environmental waste. To manufacture the pillars, shot-blasted hollow S275 steel tubes with a side length of 25 mm and a thickness of 1.5 mm were used. Bidirectional GG600T woven carbon fiber, CF, and aircraft-grade recycled carbon fiber-reinforced plastic, rCFRP, prepreg M21EV/IMA/3 were used as composite reinforcements. The first composite was made from a CF weave using the rigid epoxy resin Sicomin® 8500/Sicomin® SD8601. The rCFRP composite was frayed, and a new composite was made with the same rigid epoxy resin. Both composites were joined to the steel tube using a tough structural adhesive (SikaPower® 1277). A third composite was obtained using the frayed rCFRP and the structural adhesive as a polymer matrix. All composites were treated with an APPT (atmospheric-pressure plasma torch) before being joined to the steel pillar with the structural adhesive. The comparison of the three reinforcements showed that the steel reinforced with the recycled prepreg composite manufactured with the rigid adhesive performed best, with a 50% increase in specific bending strength and only a 32% increase in weight. It also absorbed 71% more energy, which shows that this novel option for upcycling can noticeably increase the crashworthiness of structures.
Año de publicación: 2024
3D Capsule Compliant Gripper Based on Shape Optimization for Surgical Manipulation: Enhancing Precision in Lymph Node Isolation
Compliant grippers hold great promise in improving precision and safety in Minimally Invasive Surgery (MIS), offering versatile solutions for tissue manipulation while minimizing trauma. A novel focus on a capsule-shaped compliant gripper introduces innovative design methodologies, including shape optimization and consideration of axillary lymph node dimensions. By integrating compliant beams internally and optimizing their shape and size, this gripper offers enhanced precision and adaptability in tissue manipulation, addressing specific challenges in delicate surgical interventions such as lymph node dissection in breast cancer surgery. An isogeometric approach for the analysis of geometrically nonlinear beam structures enables a seamless integration of exact geometry in CAD (Computer-Aided Design) into the analysis framework. It incorporates frictionless beam contact conditions based on a regularized penalty law, which enables an efficient and accurate simulation of the compliant grippers. Optimization results demonstrate the efficacy of the methodology in shape optimizing a set of compliant beams tailored for delicate tissue manipulation. Continued research and refinement of these methodologies are essential for furthering the field of compliant gripper design and their application in medical and surgical contexts.
Año de publicación: 2024
Compliant grippers hold great promise in improving precision and safety in Minimally Invasive Surgery (MIS), offering versatile solutions for tissue manipulation while minimizing trauma. A novel focus on a capsule-shaped compliant gripper introduces innovative design methodologies, including shape optimization and consideration of axillary lymph node dimensions. By integrating compliant beams internally and optimizing their shape and size, this gripper offers enhanced precision and adaptability in tissue manipulation, addressing specific challenges in delicate surgical interventions such as lymph node dissection in breast cancer surgery. An isogeometric approach for the analysis of geometrically nonlinear beam structures enables a seamless integration of exact geometry in CAD (Computer-Aided Design) into the analysis framework. It incorporates frictionless beam contact conditions based on a regularized penalty law, which enables an efficient and accurate simulation of the compliant grippers. Optimization results demonstrate the efficacy of the methodology in shape optimizing a set of compliant beams tailored for delicate tissue manipulation. Continued research and refinement of these methodologies are essential for furthering the field of compliant gripper design and their application in medical and surgical contexts.
Año de publicación: 2024
Analytical Modelling of an Active Vibration Absorber for a Beam
Attenuation of mechanical vibrations is an ongoing field of research in engineering aiming at reducing damage and improving performance in the presence of dynamical forces. Different alternatives have been proposed over time; the active vibration absorber can be highlighted as an alternative which can absorb the vibration from system in real time. In this study, an active vibration absorber was modelled as an electromechanical device. It was applied to a cantilever beam, mathematically modelled as a continuous beam. A set of differential equations representing the dynamical behaviour of the cantilever beam and active vibration absorber was obtained and it was simulated in Matlab Simulink®. Results indicated that the active vibration absorber is able to significantly reduce the vibration amplitudes of a system, especially in resonance conditions. The analytical model and procedure developed here can easily spread to any more complex system.
Año de publicación: 2023
Attenuation of mechanical vibrations is an ongoing field of research in engineering aiming at reducing damage and improving performance in the presence of dynamical forces. Different alternatives have been proposed over time; the active vibration absorber can be highlighted as an alternative which can absorb the vibration from system in real time. In this study, an active vibration absorber was modelled as an electromechanical device. It was applied to a cantilever beam, mathematically modelled as a continuous beam. A set of differential equations representing the dynamical behaviour of the cantilever beam and active vibration absorber was obtained and it was simulated in Matlab Simulink®. Results indicated that the active vibration absorber is able to significantly reduce the vibration amplitudes of a system, especially in resonance conditions. The analytical model and procedure developed here can easily spread to any more complex system.
Año de publicación: 2023
On the bending collapse behavior of rectangular hollow steel shapes of various thicknesses
Rectangular hollow steel shapes are widely used in numerous engineering areas due to their availability and price. In large vehicles, such as buses, these shapes also contribute to the overall crashworthiness of the vehicle, as they absorb most of the kinetic energy of an impact, and dissipate it as localized plastic deformation during a process known as bending collapse. Since a correct calculation of the crashworthiness of a structure is vital to ensure the safety of the occupants of a vehicle, special care must be taken to address the bending collapse behavior, as it is a major energy absorption mechanism. This research aims to investigate the effects and influence of thickness of the hollow shape on the bending collapse characteristics, and thus on the crashworthiness of a vehicle. Furthermore, regulations regarding crashworthiness often require some sort of experimental validation of the zones that undergo bending collapse. However, since there is no standardized test for bending collapse, the results from two types of experimental setups are compared, to study the influence of the setup on the bending collapse behavior. The results provide a detailed understanding of the failure modes of these shapes under bending loads. Additionally, the research provides insights into the design and optimization of rectangular hollow steel shapes, which will be useful to engineers and designers in the selection of thicknesses that are most appropriate for specific applications.
Año de publicación: 2023
Rectangular hollow steel shapes are widely used in numerous engineering areas due to their availability and price. In large vehicles, such as buses, these shapes also contribute to the overall crashworthiness of the vehicle, as they absorb most of the kinetic energy of an impact, and dissipate it as localized plastic deformation during a process known as bending collapse. Since a correct calculation of the crashworthiness of a structure is vital to ensure the safety of the occupants of a vehicle, special care must be taken to address the bending collapse behavior, as it is a major energy absorption mechanism. This research aims to investigate the effects and influence of thickness of the hollow shape on the bending collapse characteristics, and thus on the crashworthiness of a vehicle. Furthermore, regulations regarding crashworthiness often require some sort of experimental validation of the zones that undergo bending collapse. However, since there is no standardized test for bending collapse, the results from two types of experimental setups are compared, to study the influence of the setup on the bending collapse behavior. The results provide a detailed understanding of the failure modes of these shapes under bending loads. Additionally, the research provides insights into the design and optimization of rectangular hollow steel shapes, which will be useful to engineers and designers in the selection of thicknesses that are most appropriate for specific applications.
Año de publicación: 2023
On the Use of Carbon Fiber Composites for the Enhancement of the Rollover Resistance of Steel Buses
The increasing use of composites in vehicles in recent years is one of the current trends in the automotive industry. In particular, fiber composites are being used as reinforcements for the main structural elements of vehicles, due to their outstanding specific mechanical properties and low weight. When combined with metal parts, fiber composites can significantly enhance the crashworthiness of vehicle structures, by increasing their energy absorption capabilities and resistance to plastic deformations and permanent damage. This work presents CFRP reinforcements as a case study for enhancing the bending collapse behavior and crashworthiness of bus structures. The required calculations are based on a simplified “concept model” that includes the bending collapse behavior of the structural components, based on theoretical models calibrated with experimental results. The results demonstrate that the use of CFRP reinforcements improves the rollover crashworthiness of a bus structure, and need not be applied to the entire structure, but only to the critical parts where bending collapse is most likely to occur in a rollover accident.
Año de publicación: 2023
The increasing use of composites in vehicles in recent years is one of the current trends in the automotive industry. In particular, fiber composites are being used as reinforcements for the main structural elements of vehicles, due to their outstanding specific mechanical properties and low weight. When combined with metal parts, fiber composites can significantly enhance the crashworthiness of vehicle structures, by increasing their energy absorption capabilities and resistance to plastic deformations and permanent damage. This work presents CFRP reinforcements as a case study for enhancing the bending collapse behavior and crashworthiness of bus structures. The required calculations are based on a simplified “concept model” that includes the bending collapse behavior of the structural components, based on theoretical models calibrated with experimental results. The results demonstrate that the use of CFRP reinforcements improves the rollover crashworthiness of a bus structure, and need not be applied to the entire structure, but only to the critical parts where bending collapse is most likely to occur in a rollover accident.
Año de publicación: 2023
Development of a novel synthesis method of a rigid-body four-bar linkage into a compliant mechanism
The four-bar linkage mechanism is widely used in various machinery applications. This study presents a synthesis method to transform a rigid-body four-bar mechanism into a compliant mechanism using four leaf-type hinges based on linear theory and Castigliano's Theorem. The objective is to determine the dimensions and configuration of a flexible four-bar mechanism that replicates the behavior of the initial rigid-body mechanism. The meeting point between the two mechanisms is the flexure hinge of the compliant mechanism, which is determined using the Pseudo-Rigid-Body model (PRBM). To validate the proposed method, a program based on non-linear theory is employed. The results confirm that the dimensional differences between the two are minimal, ranging from 0% to 0.13%. This study demonstrates the feasibility of synthesizing a Rigid-Body Four-Bar Mechanism into a compliant mechanism using the PRBM, as long as the deformations are within the linear domain.
Año de publicación: 2023
The four-bar linkage mechanism is widely used in various machinery applications. This study presents a synthesis method to transform a rigid-body four-bar mechanism into a compliant mechanism using four leaf-type hinges based on linear theory and Castigliano's Theorem. The objective is to determine the dimensions and configuration of a flexible four-bar mechanism that replicates the behavior of the initial rigid-body mechanism. The meeting point between the two mechanisms is the flexure hinge of the compliant mechanism, which is determined using the Pseudo-Rigid-Body model (PRBM). To validate the proposed method, a program based on non-linear theory is employed. The results confirm that the dimensional differences between the two are minimal, ranging from 0% to 0.13%. This study demonstrates the feasibility of synthesizing a Rigid-Body Four-Bar Mechanism into a compliant mechanism using the PRBM, as long as the deformations are within the linear domain.
Año de publicación: 2023
Analytical modelling of a dynamic vibration absorber for Parkinson disease
Parkinson is the most common neurodegenerative disease. It is characterized by the presence of involuntary tremor of human arms. Current treatments as pharmacological and surgery can be invasive for patients due to secondary effects and also high costs are required. In this sense, non-invasives devices have been proposed in order to reduce the tremor amplitude without secondary effects. These devices require a model in order to analyze the dynamic behavior and calculate the optimum parameters. In this article, it is developed an analytical three-dimensional model of a dynamic vibration absorber placed on a human arm. Results show dynamic vibration absorber is effective to reduce the tremor during voluntary motion. However, it is only effective while tremor frequencies are within a narrow range around the tuned frequency used for calculation of absorber parameters.
Año de publicación: 2023
Parkinson is the most common neurodegenerative disease. It is characterized by the presence of involuntary tremor of human arms. Current treatments as pharmacological and surgery can be invasive for patients due to secondary effects and also high costs are required. In this sense, non-invasives devices have been proposed in order to reduce the tremor amplitude without secondary effects. These devices require a model in order to analyze the dynamic behavior and calculate the optimum parameters. In this article, it is developed an analytical three-dimensional model of a dynamic vibration absorber placed on a human arm. Results show dynamic vibration absorber is effective to reduce the tremor during voluntary motion. However, it is only effective while tremor frequencies are within a narrow range around the tuned frequency used for calculation of absorber parameters.
Año de publicación: 2023
Compliant Finger Gripper Based on Topology Optimization
We present the design of a compliant finger based on the topology optimization method through Hill Climber stochastic search. The compliant finger is composed of an arrangement of beams, whose behavior is studied under the formulation of large deformation co-rotational beam elements. The design optimization seeks to maximize deflection of the tip of the compliant finger with the lowest possible input torque and the mechanical advantage via the contact force between the compliant finger and a free-form shaped object. Large tip deformation is sought along a desired path. The actual path traced by the candidate mechanism and the desired path are compared through their Fourier descriptors. Computation of the contact force is performed between the surfaces of Euler-Bernoulli beam and a prescribed free-form shape.
Año de publicación: 2023
We present the design of a compliant finger based on the topology optimization method through Hill Climber stochastic search. The compliant finger is composed of an arrangement of beams, whose behavior is studied under the formulation of large deformation co-rotational beam elements. The design optimization seeks to maximize deflection of the tip of the compliant finger with the lowest possible input torque and the mechanical advantage via the contact force between the compliant finger and a free-form shaped object. Large tip deformation is sought along a desired path. The actual path traced by the candidate mechanism and the desired path are compared through their Fourier descriptors. Computation of the contact force is performed between the surfaces of Euler-Bernoulli beam and a prescribed free-form shape.
Año de publicación: 2023
Lateral Dynamic Simulation of a Bus under Variable Conditions of Camber and Curvature Radius
The objective of this paper is to describe a model for the simulation of the lateral dynamics of a vehicle, specifically buses, under variable trajectory conditions, such as camber and radius...
Año de publicación: 2022
The objective of this paper is to describe a model for the simulation of the lateral dynamics of a vehicle, specifically buses, under variable trajectory conditions, such as camber and radius...
Año de publicación: 2022
Experimental and numerical studies of polyamide 11 and 12 surfaces modified by atmospheric pressure plasma treatment
Polyamide 11 and 12 (PA11 and PA12) have been applicable in various industries, including automotive, oil and gas, and sporting goods, over the past 70 years. Although they have good dyeability, their adhesion to other materials is limited due to relatively poor surface properties, which can be promoted by good wettability and high surface energy. This study aims to improve the surface properties of PA11 and PA12 by employing the advanced method of Atmospheric Pressure Plasma Torch (APPT) treatment. In this regard, the adhesion strengths of four commercially available adhesives were evaluated with the pull-off test on PAs plates before and after APPT treatment. The numerical simulation of this test was carried out in commercial finite element software using a cohesive zone model (CZM) to predict the fracture of adhesively bonded joints. Moreover, the modified PAs were analyzed using XPS, DSC, ATR-FTIR, optical profilometer and surface energy measurement. The results indicated that the surface properties, including wettability, polar surface energy and adhesion bonding, improved by employing the plasma treatment on PAs surfaces. The numerical simulation outcomes showed that the pull-off test might be a viable alternative to determine the CZM laws for fracture mode I.
Año de publicación: 2022
Polyamide 11 and 12 (PA11 and PA12) have been applicable in various industries, including automotive, oil and gas, and sporting goods, over the past 70 years. Although they have good dyeability, their adhesion to other materials is limited due to relatively poor surface properties, which can be promoted by good wettability and high surface energy. This study aims to improve the surface properties of PA11 and PA12 by employing the advanced method of Atmospheric Pressure Plasma Torch (APPT) treatment. In this regard, the adhesion strengths of four commercially available adhesives were evaluated with the pull-off test on PAs plates before and after APPT treatment. The numerical simulation of this test was carried out in commercial finite element software using a cohesive zone model (CZM) to predict the fracture of adhesively bonded joints. Moreover, the modified PAs were analyzed using XPS, DSC, ATR-FTIR, optical profilometer and surface energy measurement. The results indicated that the surface properties, including wettability, polar surface energy and adhesion bonding, improved by employing the plasma treatment on PAs surfaces. The numerical simulation outcomes showed that the pull-off test might be a viable alternative to determine the CZM laws for fracture mode I.
Año de publicación: 2022