Publications by Pedro Miguel Nunes Pereira de Almeida Reis

A Numerical Study on the Buckling of Near-Perfect Spherical Shells

Pedro Miguel Nunes Pereira de Almeida Reis

We present the results from a numerical investigation using the finite element method to study the buckling strength of near-perfect spherical shells containing a single, localized, Gaussian-dimple defect whose profile is systematically varied toward the l ...

ASME International2025

The most severe imperfection governs the buckling strength of pressurized multi-defect hemispherical shells

Pedro Miguel Nunes Pereira de Almeida Reis, Dong Yan, Arefeh Abbasi, Fani Derveni

We perform a probabilistic investigation on the effect of systematically removing imperfections on the buckling behavior of pressurized thin, elastic, hemispherical shells containing a distribution of defects. We employ finite element simulations, which we ...

2025

Roadmap on Embodying Mechano-intelligence and Computing in Functional Materials and Structures

Pedro Miguel Nunes Pereira de Almeida Reis

This is a roadmap article with multiple contributors on different aspects of embodying intelligence and computing in the mechanical domain of functional materials and structures. Overall, an IOP roadmap article is a broad, multi-author review with leaders ...

IOP Publishing Ltd2025

Capsizing due to friction-induced twist in the failure of stopper knots

Pedro Miguel Nunes Pereira de Almeida Reis, Paul Johanns

We investigate the failure mechanism of stopper knots, with a particular focus on the figure -8 knot as a representative example. Stopper knots are widely used in climbing, sailing, racket stringing, and sewing to maintain tension in ropes, strings, or thr ...

Elsevier2024

Microfluidic device

Pedro Miguel Nunes Pereira de Almeida Reis

Microfluidic device (1) comprising at least one conduit (9) arranged for the transport of a liquid, wherein said conduit (9) comprises at least one flexible element (11; 11a; 11b; 11c; 15; 15a; 15b) arranged to be reversibly movable between at least a firs ...

2024

Stick-slip in a stack: How slip dissonance reveals aging

Pedro Miguel Nunes Pereira de Almeida Reis, Samuel Jean Bernard Poincloux

We perform physical and numerical experiments to study the stick -slip response of a stack of slabs in contact through dry frictional interfaces driven in quasistatic shear. The ratio between the drive's stiffness and the slab's shear stiffness controls th ...

Amer Physical Soc2024

Harnessing centrifugal and Euler forces for tunable buckling of a rotating elastica

Pedro Miguel Nunes Pereira de Almeida Reis, Michael Christopher Gomez

We investigate the geometrically nonlinear deformation and buckling of a slender elastic beam subject to time-dependent ‘fictitious’ (non-inertial) forces arising from unsteady rotation. Using a rotary apparatus that accurately imposes an angular accelerat ...

2024

Stretch-independent magnetization in incompressible isotropic hard magnetorheological elastomers

Pedro Miguel Nunes Pereira de Almeida Reis

Recent studies on magnetically hard, particle-filled magnetorheological elastomers (h-MREs) have revealed their stretch-independent magnetization response after full pre-magnetization. We discuss this phenomenon, focusing on incompressible, isotropic, part ...

2024

Regulation ofthe swimming kinematics oflampreys Petromyzon marinusacross changes in viscosity

Pedro Miguel Nunes Pereira de Almeida Reis, Yuexia Luna Lin

The bodies of most swimming fishes are very flexible and deform as result of both external fluid dynamic forces and internal musculoskeletal forces. If fluid forces change, the body motion will also change unless the fish senses the change and alters its m ...

COMPANY BIOLOGISTS LTD2023

Fluid-structure interactions of bristled wings: the trade-off between weight and drag

Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla, Yuexia Luna Lin

The smallest flying insects often have bristled wings resembling feathers or combs. We combined experiments and three-dimensional numerical simulations to investigate the trade-off between wing weight and drag generation. In experiments of bristled strips, ...

Royal Soc2023

Leveraging the Snap Buckling of Bistable Magnetic Shells to Design a Refreshable Braille Dot

Pedro Miguel Nunes Pereira de Almeida Reis, Bastien Freddy Gustave Aymon, Arefeh Abbasi, Tian Chen

A design concept is proposed for the building block, a dot, of programmable braille readers utilizing bistable shell buckling, magnetic actuation, and pneumatic loading. The design process is guided by Finite Element simulations, which are initially valida ...

Wiley2023

Comparing the Buckling Strength of Spherical Shells With Dimpled Versus Bumpy Defects

Pedro Miguel Nunes Pereira de Almeida Reis, Arefeh Abbasi, Fani Derveni

We investigate the effect of defect geometry in dictating the sensitivity of the critical buckling conditions of spherical shells under external pressure loading. Specifically, we perform a comparative study between shells containing dimpled (inward) versu ...

ASME2023

A reduced-order, rotation-based model for thin hard-magnetic plates

Pedro Miguel Nunes Pereira de Almeida Reis, Dong Yan, Bastien Freddy Gustave Aymon

We develop a reduced-order model for thin plates made of hard magnetorheological elastomers (hard-MREs), which are composed of hard-magnetic particles embedded in a polymeric matrix. First, we propose a new magnetic potential, as an alternative to an exist ...

PERGAMON-ELSEVIER SCIENCE LTD2023

Indentation and stability of woven domes

Célestin Vallat, Pedro Miguel Nunes Pereira de Almeida Reis, Tomohiko Sano, Tian Chen, Samuel Jean Bernard Poincloux

Discrete domes are doubly curved structures comprising a network of beam-like elements. We study the mechanics of discrete domes made of ribbons woven in a pentagonal triaxial pattern. Experiments and finite element simulations are performed to characteriz ...

ELSEVIER2023

Snap buckling of bistable beams under combined mechanical and magnetic loading

Pedro Miguel Nunes Pereira de Almeida Reis, Dong Yan, Tomohiko Sano, Arefeh Abbasi

We investigate the mechanics of bistable, hard-magnetic, elastic beams, combining experiments, finite-element modelling (FEM) and a reduced-order theory. The beam is made of a hard magneto-rheological elastomer, comprising two segments with antiparallel ma ...

ROYAL SOC2023

Twisting instabilities in elastic ribbons with inhomogeneous pre-stress: A macroscopic analog of thermodynamic phase transition

Pedro Miguel Nunes Pereira de Almeida Reis, Michael Christopher Gomez

We study elastic ribbons subject to large, tensile pre-stress confined to a central region within the cross-section. These ribbons can buckle spontaneously to form helical shapes, featuring regions of alternating chirality (phases) that are separated by so ...

PERGAMON-ELSEVIER SCIENCE LTD2023

The strength of surgical knots involves a critical interplay between friction and elastoplasticity

Paul Grandgeorge, Pedro Miguel Nunes Pereira de Almeida Reis, Paul Johanns, Changyeob Baek

Knots are the weakest link in surgical sutures, serving as mechanical ligatures between filaments. Exceeding their safe operational limits can cause fatal complications. The empirical nature of present guidelines calls for a predictive understanding of the ...

AMER ASSOC ADVANCEMENT SCIENCE2023

Probabilistic buckling of imperfect hemispherical shells containing a distribution of defects

Pedro Miguel Nunes Pereira de Almeida Reis, Dong Yan, Fani Derveni

The buckling of spherical shells is plagued by a strong sensitivity to imperfections. Traditionally, imperfect shells tend to be characterized empirically by the knockdown factor, the ratio between the measured buckling strength and the corresponding class ...

ROYAL SOC2023

Tapered foils favor traveling-wave kinematics to enhance the performance of flapping propulsion

Karen Ann J Mulleners, Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla

We report results from an experimental investigation on the fluid-structure interactions of flapping foils with tapered thickness profiles actuated in a quiescent viscous fluid. We seek to assess the propulsive performance of two sets of flapping foils; on ...

2022

A geometrically exact model for thin magneto-elastic shells

Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla, Dong Yan

We develop a reduced model for hard-magnetic, thin, linear-elastic shells that can be actuated through an external magnetic field, with geometrically exact strain measures. Assuming a reduced kinematics based on the Kirchhoff-Love assumption, we derive a r ...

PERGAMON-ELSEVIER SCIENCE LTD2022