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Bifurcation & Chaos in Nonlinear Structural Dynamics: Novel & Highly Efficient Optimal-Feedback Accelerated Picard Iteration Algorithms

A new class of algorithms for solving nonlinear structural dynamical problems are derived in the present paper, as being based on optimal-feedback-accelerated Picard iteration, wherein the solution vectors for the displacements and velocities at any time in a finitely large time interval are corrected by a weighted (with a matrix) integral of the error. We present 3 approximations to solve the Euler-Lagrange equations for the optimal weighting functions; thus we present 3 algorithms denoted as Optimal-Feedback-Accelerated Picard Iteration (OFAPI) algorithms-1, 2, 3.

Alejandro Ortiz-Bernardin's picture

Release of VEMLab v2.1

VEMLab: a MATLAB library for the virtual element method


Release of VEMLab v2.1


>>  From VEMLab v2.0.2 to VEMLab v2.1:


- Add customized wrench domain (for PolyMesher mesh generator only).


- Add customized plate with a hole domain (for PolyMesher mesh generator only).


- Add the following test: “square_plate_with_source2_poisson2d.m” in test folder.


Osama R. Bilal's picture

No motor, no battery, no problem

New robot concept uses responsive materials to swim through water

Arash_Yavari's picture

Line and Point Defects in Nonlinear Anisotropic Solids

In this paper, we present some analytical solutions for the stress fields of nonlinear anisotropic solids with distributed line and point defects.

£1 million awarded for 5 year project for virtual testing of components

Simpleware software user Dr. Llion Evans of Swansea University and the Culham Centre for Fusion Energy has received £1 million in funding for a five-year project into virtual testing of new components. Funded by the Engineering and Physical Sciences Research Council (EPSRC), the research looks at how image-based simulation using 3D X-ray imaging can virtually evaluate manufactured components.

marco.paggi's picture

Wiki surface - an open access encyclopedia of surfaces

Dear Mechanicians,

a new project at the IMT School for Advanced Studies Lucca (Lucca, Italy) has just been launched to create the first open access database of rough surfaces from nature and technology, see:

People are invited to contribute to the database by providing images of surfaces acquired using experimental techniques, as well as the corresponding elevation data field (raw x,y,z data in columns).

Rui Xiao's picture

Aging-dependent strain localization in amorphous glassy polymers: from necking to shear banding

This study investigates the influence of physical aging on the deformation behaviors of poly(ethylene terephthalate)-glycol. The polymers are subjected to a quenched and an annealed heat treatment, followed by deformation in tension. The digital image correlation (DIC) is used to capture the surface strain. The DIC results show that the deformation localization occurs in the post-yield strain softening region. The quenched and annealed polymers exhibit different localization types, representing as necking for quenched polymers and shear banding for annealed polymers.

Jianying's picture

Journal Club for May 2018: Icephobic Materials

Icephobic Materials

Yizhi Zhuo, Jianying He

NTNU Nanomechanical Lab, Norwegian University of Science and Technology (NTNU)


oliver oreilly's picture

A Free Primer on the Kinematics of Discrete Elastic Rods

A new book, A Primer on the Kinematics of Discrete Elastic Rods, has just been published by Springer and is freely accessible to faculty and students at

Oleg Kirillov's picture

The first experimental evidence of the Ziegler destabilization paradox

A “flutter machine” is introduced for the investigation of a singular interface between the classical and reversible Hopf bifurcations that is theoretically predicted to be generic in nonconservative reversible systems with vanishing dissipation. In particular, such a singular interface exists for the Pflüger viscoelastic column moving in a resistive medium, which is proven by means of the perturbation theory of multiple eigenvalues with the Jordan block.

MNasr's picture

Novel silicon nanowire-based 3-dimensional devices and systems

A new approach for monolithic integration of silicon nanowires with 3-dimensional devices (for more details of the project see: Integration of silicon nanowires in three-dimensional devices including integrated circuits (ICs) and microelectromechanical systems (MEMS) leads to enhanced functionality and performance in diverse applications.

Jingjie Yeo's picture

Materials-by-design: computation, synthesis, and characterization from atoms to structures In the 50 years that succeeded Richard Feynman’s exposition of the idea that there is "plenty of room at the bottom" for manipulating individual atoms for the synthesis and manufacturing processing of materials, the materials-by-design paradigm is being developed gradually through synergistic integration of experimental material synthesis and characterization with predictive computational modeling and optimization.

Biomechanical Testing

Biomechanics & Biomechanical Testing

Full blog post can be found here

Key concepts for medical device design include biomechanics, biocompatibility, and biofunctionality. This post will go over the mechanics of an exemplar biological tissue, the bone, and mechanical testing of biomaterials that are used in developing medical devices and equipment.

Qiming Wang's picture

Magnetoactive Acoustic Metamaterials

Kunhao Yu, Nicholas X. Fang, Guoliang Huang, Qiming Wang, Magnetoactive Acoustic Metamaterials, Advanced Materials, 1706348, 2018.

Jingjie Yeo's picture

Effects of oscillating pressure on desalination performance of transverse flow CNT membrane In parallel with recent developments in carbon nanomaterials, there is growing interest in using these nanomaterials for desalination. To date, many studies have affirmed the potential of using such nanomaterials for constant pressure desalination operation. In this work, the performance of such membrane when subjected to oscillatory pressure at sub-nanosecond is investigated in detail.

GTN model

I have 2 questions regarding GTN model.

1) What does q1, q2, q3 signify in GTN damage model? What are their physical meanings. I know only their numerical values.
2) How to deal with the problem of GTN in Compression? It is working fine with tension but while in compression it is unable to converge.

Qunyang Li's picture

Journal club for April 2018: Friction of atomically-thin sheets

Friction of atomically-thin sheets

Qunyang Li

Department of Engineering Mechanics, Tsinghua University



Alejandro Ortiz-Bernardin's picture

A volume-averaged nodal projection method for the Reissner-Mindlin plate model

We introduce a novel meshfree Galerkin method for the solution of Reissner-Mindlin plate problems that is written in terms of the primitive variables only (i.e., rotations and transverse displacement) and is devoid of shear-locking.

Refat_Islam's picture

Mechanics of Mushroom as a material

We recently characterized a unique material developed from root structure (Mycelium) of mushroom. Mycelium has a filamentous network structure with mechanics largely controlled by filament elasticity and branching, and network density. We report the morphological and mechanical characterization of mycelium. The monotonic mechanical behavior of the mycelium is non-linear both in tension and compression.

zappalorto's picture

The 7th edition of the International Conference on Fatigue of Composites (ICFC7)

The 7th edition of the International Conference on Fatigue of Composites is going to be held in Vicenza (Italy) from 4th to 6th of July 2018. The conference is organized by the Department of Management and Engineering at the University of Padova, under the patronage of the European Society for Composite Materials, the Committee on Composite Materials of the Japan Society of Material Science, the Italian Association for Stress Analysis and the Italian Group of Fracture.


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