Nonlinear model reduction for large-scale structures via dual substructuring
This work presents a nonlinear model reduction strategy for large-scale structural systems with localized nonlinearities based on a dual substructuring approach. The method combines the computational benefits of the dual Craig-Bampton formulation with the accuracy of nonlinear normal modes (NNMs) embedded within each substructure dynamic reduction. Internal nonlinearities are treated locally via invariant manifold-based approximations, while interface compatibility is enforced through interface forces, maintaining the modularity and flexibility of the dual formulation. The performance of the proposed method is assessed on a steel frame with localized nonlinearities subjected to harmonic loading. The results obtained with the proposed formulation were compared with those of the full finite element model. In both analyses, the Hilber–Hughes–Taylor (HHT) algorithm was employed as the time integration strategy. The reduced models achieve significant reductions in computational cost while preserving high accuracy in the predicted transient response. The approach demonstrates strong potential for efficient nonlinear dynamic simulation of complex engineering structures with localized nonlinearities.
Año de publicación: 2026
This work presents a nonlinear model reduction strategy for large-scale structural systems with localized nonlinearities based on a dual substructuring approach. The method combines the computational benefits of the dual Craig-Bampton formulation with the accuracy of nonlinear normal modes (NNMs) embedded within each substructure dynamic reduction. Internal nonlinearities are treated locally via invariant manifold-based approximations, while interface compatibility is enforced through interface forces, maintaining the modularity and flexibility of the dual formulation. The performance of the proposed method is assessed on a steel frame with localized nonlinearities subjected to harmonic loading. The results obtained with the proposed formulation were compared with those of the full finite element model. In both analyses, the Hilber–Hughes–Taylor (HHT) algorithm was employed as the time integration strategy. The reduced models achieve significant reductions in computational cost while preserving high accuracy in the predicted transient response. The approach demonstrates strong potential for efficient nonlinear dynamic simulation of complex engineering structures with localized nonlinearities.
Año de publicación: 2026
Experimental Study of the Axial Crushing Mechanics of Yoshimura Tubes
Origami has inspired a wide range of engineering applications, from deployable systems to structures with enhanced mechanical performance. In this context, Yoshimura patterns, commonly observed during the axial crushing of circular thin-walled tubes, offer a promising basis for designing energy-absorbing components. This paper presents an experimental investigation into how the geometric parameters of a Yoshimura cylindrical tube influence its axial crushing response. The parameters examined include the in-plane panel angle and the number of sides around the circumference. The results indicate that these geometric features significantly affect both the peak load and the energy absorbed during collapse. Higher in-plane angles lead to increased peak loads and stiffness within the tested range, while tubes with fewer sides, particularly three, exhibit a more gradual post-peak load reduction. Conversely, tubes with a larger number of sides show a sharper drop in load after the peak. These findings demonstrate that the crushing mechanics of Yoshimura tubes can be tailored to specific energy-absorption requirements through appropriate geometric design.
Año de publicación: 2026
Origami has inspired a wide range of engineering applications, from deployable systems to structures with enhanced mechanical performance. In this context, Yoshimura patterns, commonly observed during the axial crushing of circular thin-walled tubes, offer a promising basis for designing energy-absorbing components. This paper presents an experimental investigation into how the geometric parameters of a Yoshimura cylindrical tube influence its axial crushing response. The parameters examined include the in-plane panel angle and the number of sides around the circumference. The results indicate that these geometric features significantly affect both the peak load and the energy absorbed during collapse. Higher in-plane angles lead to increased peak loads and stiffness within the tested range, while tubes with fewer sides, particularly three, exhibit a more gradual post-peak load reduction. Conversely, tubes with a larger number of sides show a sharper drop in load after the peak. These findings demonstrate that the crushing mechanics of Yoshimura tubes can be tailored to specific energy-absorption requirements through appropriate geometric design.
Año de publicación: 2026
MECAPUCP: Interactive Teaching Tool for Mechanism Kinematics
This paper presents MECAPUCP, an interactive desktop application developed in Python to support the teaching of planar kinematics as a foundational step for Engineering Dynamics, as well as Mechanism and Machine Theory. This tool combines a graphical user interface built with Tkinter, a numerical engine based on vectorized computations in NumPy and root-finding routines in SciPy, and real-time visualization of motion and kinematic variables using Matplotlib. MECAPUCP includes several classical mechanisms such as the slider-crank, four-bar linkage, Whitworth quick-return, to name a few, within a unified workflow for parameter definition, simulation, animation, and analysis. The contributions of this work are as follows: (i) It synthesizes a coherent theoretical framework for teaching kinematic analysis using a single software tool that is closely aligned with lecture content. (ii) It introduces a modular architecture that enables new mechanisms to be added with minimal modifications to the existing code. (iii) It demonstrates how the application can be used by students to verify manual calculations by comparing numerical results with hand-solved kinematic problems. (iv) It provides a practical evaluation tool for assessments or exams, allowing instructors to gauge students’ conceptual understanding through simulation-based tasks.
Año de publicación: 2026
This paper presents MECAPUCP, an interactive desktop application developed in Python to support the teaching of planar kinematics as a foundational step for Engineering Dynamics, as well as Mechanism and Machine Theory. This tool combines a graphical user interface built with Tkinter, a numerical engine based on vectorized computations in NumPy and root-finding routines in SciPy, and real-time visualization of motion and kinematic variables using Matplotlib. MECAPUCP includes several classical mechanisms such as the slider-crank, four-bar linkage, Whitworth quick-return, to name a few, within a unified workflow for parameter definition, simulation, animation, and analysis. The contributions of this work are as follows: (i) It synthesizes a coherent theoretical framework for teaching kinematic analysis using a single software tool that is closely aligned with lecture content. (ii) It introduces a modular architecture that enables new mechanisms to be added with minimal modifications to the existing code. (iii) It demonstrates how the application can be used by students to verify manual calculations by comparing numerical results with hand-solved kinematic problems. (iv) It provides a practical evaluation tool for assessments or exams, allowing instructors to gauge students’ conceptual understanding through simulation-based tasks.
Año de publicación: 2026
A dual Craig-Bampton substructuring method for nonlinear systems using nonlinear normal modes
In flexible mechanical systems, nonlinearities frequently arise in the equations of motion due to factors such as large deformations, nonlinear force interactions, or material behavior. When transient dynamic analysis is performed using the finite element method (FEM), these nonlinearities can significantly increase computational cost. Model order reduction techniques that preserve essential nonlinear dynamics are thus critical for efficient simulation. This paper proposes a nonlinear extension of the Dual Craig-Bampton (DCB) substructuring method for systems with non-classical damping. The approach incorporates nonlinear normal modes (NNMs), constructed via invariant manifold theory, into the dynamic component of the reduction. Two numerical case studies are presented: a cantilever Bernoulli beam with cubic stiffness at its support, and a planar truss structure with nonlinear springs, both subjected to harmonic loading. The proposed method achieves excellent agreement with full-model simulations using the Hilber-Hughes-Taylor (HHT) method, while significantly reducing the number of degrees of freedom. Results demonstrate the method’s potential for accurate and efficient nonlinear transient analysis in structural dynamics.
Año de publicación: 2026
In flexible mechanical systems, nonlinearities frequently arise in the equations of motion due to factors such as large deformations, nonlinear force interactions, or material behavior. When transient dynamic analysis is performed using the finite element method (FEM), these nonlinearities can significantly increase computational cost. Model order reduction techniques that preserve essential nonlinear dynamics are thus critical for efficient simulation. This paper proposes a nonlinear extension of the Dual Craig-Bampton (DCB) substructuring method for systems with non-classical damping. The approach incorporates nonlinear normal modes (NNMs), constructed via invariant manifold theory, into the dynamic component of the reduction. Two numerical case studies are presented: a cantilever Bernoulli beam with cubic stiffness at its support, and a planar truss structure with nonlinear springs, both subjected to harmonic loading. The proposed method achieves excellent agreement with full-model simulations using the Hilber-Hughes-Taylor (HHT) method, while significantly reducing the number of degrees of freedom. Results demonstrate the method’s potential for accurate and efficient nonlinear transient analysis in structural dynamics.
Año de publicación: 2026
Systematic mapping of synthesis methods for compliant grippers using PRISMA
Systematic design, development and applications of Compliant Grippers (CGs) have surged in the past decade. The works are diverse but information is dispersed. This paper provides a systematic review of 1009 peer reviewed manuscripts in the last ten years, sourced from the Scopus database. Keywords search on CG design, analytical methods, gripper size and design verification. 239 papers are mapped onto applications, types of workpieces, actuation technologies, focusing onto CG design methodologies. Actuation methods are classified into indirect and direct. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol is followed. Key findings include: (i) CGs are mostly designed with direct mechanical load actuation, the corresponding synthesis methods follow well defined processes; (ii) Most CGs cater to convex, regular and small objects; (iii) much focus on their application is on research and development followed by manufacturing and assembly, healthcare, electronics and semiconductors and food processing; (iv) fluidic actuation is gaining prominence but not as much as direct actuation; and (v) systematic synthesis methods are needed for other existing and emerging technologies like controlled adhesion, smart materials and jamming.
Año de publicación: 2025
Systematic design, development and applications of Compliant Grippers (CGs) have surged in the past decade. The works are diverse but information is dispersed. This paper provides a systematic review of 1009 peer reviewed manuscripts in the last ten years, sourced from the Scopus database. Keywords search on CG design, analytical methods, gripper size and design verification. 239 papers are mapped onto applications, types of workpieces, actuation technologies, focusing onto CG design methodologies. Actuation methods are classified into indirect and direct. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol is followed. Key findings include: (i) CGs are mostly designed with direct mechanical load actuation, the corresponding synthesis methods follow well defined processes; (ii) Most CGs cater to convex, regular and small objects; (iii) much focus on their application is on research and development followed by manufacturing and assembly, healthcare, electronics and semiconductors and food processing; (iv) fluidic actuation is gaining prominence but not as much as direct actuation; and (v) systematic synthesis methods are needed for other existing and emerging technologies like controlled adhesion, smart materials and jamming.
Año de publicación: 2025
Omnidirectional Wheelchair with Suspension System for Mobility on Uneven Terrains
Wheelchairs play a crucial role in society by providing mobility and autonomy to individuals with physical disabilities, essential for their social inclusion. However, conventional wheelchairs often face significant limitations in narrow spaces and uneven terrains. The development of omnidirectional wheelchairs with suspension systems, as addressed in this work, is essential to tackle these challenges and offer greater independence to individuals with disabilities. These innovations can enhance quality of life by enabling access to previously inaccessible places and facilitating mobility in areas where, for example, sidewalks are deteriorated or nonexistent. The wheelchair was designed considering the challenges that conventional models face in terms of maneuverability and mobility in uneven terrains with small obstacles. The design process is briefly described, with a special focus on system requirements, conceptual design, hardware architecture, and the overall proposed design, along with the proposed control strategy. An analysis of the Mecanum-wheeled locomotion system when one of the wheels encounters an obstacle is also presented. It was concluded that the proposed design met the initial requirements, and that the suspension system allowed the wheelchair to navigate uneven terrains without experiencing significant changes in pitch or roll angles while keeping all four wheels in contact with the ground.
Año de publicación: 2025
Wheelchairs play a crucial role in society by providing mobility and autonomy to individuals with physical disabilities, essential for their social inclusion. However, conventional wheelchairs often face significant limitations in narrow spaces and uneven terrains. The development of omnidirectional wheelchairs with suspension systems, as addressed in this work, is essential to tackle these challenges and offer greater independence to individuals with disabilities. These innovations can enhance quality of life by enabling access to previously inaccessible places and facilitating mobility in areas where, for example, sidewalks are deteriorated or nonexistent. The wheelchair was designed considering the challenges that conventional models face in terms of maneuverability and mobility in uneven terrains with small obstacles. The design process is briefly described, with a special focus on system requirements, conceptual design, hardware architecture, and the overall proposed design, along with the proposed control strategy. An analysis of the Mecanum-wheeled locomotion system when one of the wheels encounters an obstacle is also presented. It was concluded that the proposed design met the initial requirements, and that the suspension system allowed the wheelchair to navigate uneven terrains without experiencing significant changes in pitch or roll angles while keeping all four wheels in contact with the ground.
Año de publicación: 2025
Analysis of the relative displacements in a thick Origami with double-hinge technique for thickness accommodation
Origami, the art of folding paper, has been extensively explored for its potential to produce complex structures and enable rapid and precise movements with few folds. The flexibility and low thickness of paper make it ideal for folding, although most engineering applications require stiffer and thicker materials when drawing inspiration from Origami. For that, several techniques have been developed over the years and the double-hinge technique is one of the least explored techniques for thick Origami, even though it shows a major advantage to obtain a fully flat surface in the unfolded state. This advantage makes it ideal when developing solar panels where flat surfaces are required to maximize the absorbed energy. In this work, the Miura Ori pattern, based on the degree-4 vertex coupled with the double-hinge thickness accommodation technique, is analyzed to obtain relationships between the kinematics, thickness, sector angles, and periodicity. It is found that by releasing certain degrees-of-freedom, the double-hinge technique can be used to fold Origami patterns, with flat-foldability and preserving the Origami motion. The findings of this research contribute to a deeper understanding of thickness implications in the double-hinge technique for Origami-based thickness accommodations. This study presents a novel model that has not been previously explored, establishing key insights that are crucial for future emerging applications.
Año de publicación: 2025
Origami, the art of folding paper, has been extensively explored for its potential to produce complex structures and enable rapid and precise movements with few folds. The flexibility and low thickness of paper make it ideal for folding, although most engineering applications require stiffer and thicker materials when drawing inspiration from Origami. For that, several techniques have been developed over the years and the double-hinge technique is one of the least explored techniques for thick Origami, even though it shows a major advantage to obtain a fully flat surface in the unfolded state. This advantage makes it ideal when developing solar panels where flat surfaces are required to maximize the absorbed energy. In this work, the Miura Ori pattern, based on the degree-4 vertex coupled with the double-hinge thickness accommodation technique, is analyzed to obtain relationships between the kinematics, thickness, sector angles, and periodicity. It is found that by releasing certain degrees-of-freedom, the double-hinge technique can be used to fold Origami patterns, with flat-foldability and preserving the Origami motion. The findings of this research contribute to a deeper understanding of thickness implications in the double-hinge technique for Origami-based thickness accommodations. This study presents a novel model that has not been previously explored, establishing key insights that are crucial for future emerging applications.
Año de publicación: 2025
Origami-Inspired Photovoltaic Modules—Development of Ecofriendly Solutions for Naval and Mining Operations
In recent years, ecofriendly and renewable energy solutions have gained relevance mainly to lessen the effects of climate change. Governments and companies across the world have commitments to reduce fuel consumption and emissions as part of the 2030 Sustainable Development Goals. Solar energy systems have great importance as a renewable energy source; however, they often have large space requirements to be effective, e.g., large areas covered by solar panels, as well as low efficiency and strong dependance on the weather. On the other hand, origami, the art of folding paper, can be a source of inspiration for new technologies and solutions for modern problems. In this paper, origami-inspired solar panels are presented as a potential solution for naval and mining operations. Prototype panels are manufactured based on the Miura-Ori pattern. Using this pattern, the photovoltaic modules can be folded by just one movement, thus reducing their footprint by up to 90%. The prototype photovoltaic modules are then tested on land and on board a vessel, where their efficiency and resistance can be tested. It is shown that naval and mining operations, where fuel consumption can be extremely high and available space is a major constraint, benefit greatly from this kind of development.
Año de publicación: 2025
In recent years, ecofriendly and renewable energy solutions have gained relevance mainly to lessen the effects of climate change. Governments and companies across the world have commitments to reduce fuel consumption and emissions as part of the 2030 Sustainable Development Goals. Solar energy systems have great importance as a renewable energy source; however, they often have large space requirements to be effective, e.g., large areas covered by solar panels, as well as low efficiency and strong dependance on the weather. On the other hand, origami, the art of folding paper, can be a source of inspiration for new technologies and solutions for modern problems. In this paper, origami-inspired solar panels are presented as a potential solution for naval and mining operations. Prototype panels are manufactured based on the Miura-Ori pattern. Using this pattern, the photovoltaic modules can be folded by just one movement, thus reducing their footprint by up to 90%. The prototype photovoltaic modules are then tested on land and on board a vessel, where their efficiency and resistance can be tested. It is shown that naval and mining operations, where fuel consumption can be extremely high and available space is a major constraint, benefit greatly from this kind of development.
Año de publicación: 2025
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 minimizingtrauma. A novel focus on a capsule-shaped compliant gripper introduces innovativedesign methodologies, including shape optimization and consideration of axillary lymphnode dimensions. By integrating compliant beams internally and optimizing their shape,this gripper offers enhanced precision and adaptability in tissue manipulation, addressingspecific challenges in delicate surgical interventions such as lymph node dissection inbreast cancer surgery. An isogeometric approach for the analysis of geometrically nonlinear beam structures enables a seamless integration of exact geometry in computer-aided design (CAD) 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 themethodology, producing a compliant beam configuration that applies a mean pressure of204.93 Pa, with a maximized contact area facilitating form closure gripping. Experimentalvalidation using a test bench confirms the consistency of the contact areas predicted by simulations, with force sensor measurements showing good agreement with simulation results in most cases. Minor discrepancies, particularly in higher-pressure regions, are attributed to sensor limitations but do not significantly impact the overall findings. Continued research and refinement of these methodologies are essential for furthering the field of compliant gripper design and its application in medical and surgical contexts.
Año de publicación: 2025
Compliant grippers hold great promise in improving precision and safety in minimally invasive surgery (MIS), offering versatile solutions for tissue manipulation while minimizingtrauma. A novel focus on a capsule-shaped compliant gripper introduces innovativedesign methodologies, including shape optimization and consideration of axillary lymphnode dimensions. By integrating compliant beams internally and optimizing their shape,this gripper offers enhanced precision and adaptability in tissue manipulation, addressingspecific challenges in delicate surgical interventions such as lymph node dissection inbreast cancer surgery. An isogeometric approach for the analysis of geometrically nonlinear beam structures enables a seamless integration of exact geometry in computer-aided design (CAD) 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 themethodology, producing a compliant beam configuration that applies a mean pressure of204.93 Pa, with a maximized contact area facilitating form closure gripping. Experimentalvalidation using a test bench confirms the consistency of the contact areas predicted by simulations, with force sensor measurements showing good agreement with simulation results in most cases. Minor discrepancies, particularly in higher-pressure regions, are attributed to sensor limitations but do not significantly impact the overall findings. Continued research and refinement of these methodologies are essential for furthering the field of compliant gripper design and its application in medical and surgical contexts.
Año de publicación: 2025
On the collapse mechanics of steel rectangular tubes in cantilever bending
Bending collapse is a failure mechanism in thin-walled shapes that often appear in structures under impact and high bending loads. It is characterized by the formation of a localized zone of large plastic strains, referred to as a plastic hinge, which is typically described in engineering applications by moment–rotation curves. The importance of this topic primarily lies in the estimation of the crashworthiness of vehicle structures, where tubes with rectangular hollow sections are commonly used in structures for rollover protection. In this field, both the strength and the energy absorption of the shape need to be adequately quantified. Although this topic has been covered in past and recent research, the existing studies are based on empirical deformation mechanisms and energy methods that provide limited insight into the mechanical principles governing bending collapse. In this investigation, numerical simulations are employed to analyze the influence of geometric parameters and strain hardening on the bending properties of rectangular hollow tubes. The finite element models are verified with experimental results reported in the literature. The results show that bending collapse is governed by the occurrence of local buckling in the compressed flange and sidewalls. Moreover, the moment–angle curves are correlated with stress and plastic deformation responses in the plastic hinge. This study gives acomprehensive understanding of the mechanical quantities governing the different stages of bending collapse, offering crucial insights for developing theoretical models for novel thin-walled energy absorbers
Año de publicación: 2025
Bending collapse is a failure mechanism in thin-walled shapes that often appear in structures under impact and high bending loads. It is characterized by the formation of a localized zone of large plastic strains, referred to as a plastic hinge, which is typically described in engineering applications by moment–rotation curves. The importance of this topic primarily lies in the estimation of the crashworthiness of vehicle structures, where tubes with rectangular hollow sections are commonly used in structures for rollover protection. In this field, both the strength and the energy absorption of the shape need to be adequately quantified. Although this topic has been covered in past and recent research, the existing studies are based on empirical deformation mechanisms and energy methods that provide limited insight into the mechanical principles governing bending collapse. In this investigation, numerical simulations are employed to analyze the influence of geometric parameters and strain hardening on the bending properties of rectangular hollow tubes. The finite element models are verified with experimental results reported in the literature. The results show that bending collapse is governed by the occurrence of local buckling in the compressed flange and sidewalls. Moreover, the moment–angle curves are correlated with stress and plastic deformation responses in the plastic hinge. This study gives acomprehensive understanding of the mechanical quantities governing the different stages of bending collapse, offering crucial insights for developing theoretical models for novel thin-walled energy absorbers
Año de publicación: 2025