Search results for "Mechanical engineering"

Cobalt(II)-Copper(II) Bimetallic Chains as a New Class of Single-Chain Magnets

2004

Investigation of Wood Materials by Combined Application of X-ray and Neutron Imaging Techniques*

2014

Abstract Conservation of cultural heritage is extremely important not only from a cultural point of view, but also from a practical one. It is our duty to pass on to future generations the cultural heritage left to us by our ancestors. Wood is one of the most common materials used to generate works of art which are in a state of constant change and/or deterioration. In order to optimize the knowledge of artworks together with their conservation, it is necessary to use the most advanced scientific and technological tools. In the following paper, we will show the tomographic results which can be achieved by application of complementary techniques based on the combined use of X-ray and neutron…

<title>Using infrared thermography as a tool to analyze curling and cockling of paper</title>

1992

Paper surface topology analysis with infrared thermography is described. Heat is applied perpendicular to the target. Temperature distribution of the sheet correlates well with the surface height distribution when the sheet is placed on the isothermic plate. Mathematical tools for data analysis and the mechanisms behind the curl and cockles are briefly discussed. Curl in paper and paperboard is defined as deviation from the flat form.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Integration of finite displacement interface element in reference and current configurations

2017

In the present paper the non-linear behaviour of a solid body with embedded cohesive interfaces is examined in a finite displacements context. The principal target is the formulation of a two dimensional interface finite element which is referred to a local reference frame, defined by normal and tangential unit vectors to the interface middle surface. All the geometric operators, such as the interface elongation and the reference frame, are computed as function of the actual nodal displacements. The constitutive cohesive law is defined in terms of Helmholtz free energy for unit undeformed interface surface and, in order to obtain the same nodal force vector and stiffness matrix by the two i…

Residual Stresses Induced by Cold Expansion of Adjacent and Cut-Out Holes

2012

Fatigue life of fastener holes can be enhanced via a cold-expansion process to introduce a compressive residual stress field around the hole edge and to reduce crack growth propagation. Considering that aerospace components contain multiple rows of holes, the present investigation focuses on the evaluation of the three-dimensional residual stress distribution in adjacent cold-expanded (CE) holes. The redistribution of residual stresses caused by a cut introduced between two adjacent holes was also investigated. Finite element (FE) analysis and experimental technique were used to assess the residual stress distribution in a 6082-T6 aluminum plate with two adjacent holes expanded sequentially…

Cultivation of algae with indigenous species – Potentials for regional biofuel production

2011

The massive need for sustainable energy has led to an increased interest in new energy resources, such as production of algae, for use as biofuel. There are advantages to using algae, for example, ...

Experimental modeling of bacterially-induced Ca carbonate precipitation: new insights on possible mechanisms.

2015

The contribution of microorganisms, particularly bacteria, in carbonate mineral formation, the main natural processes controlling CO2 level in the atmosphere, has played an important role since the Archean Eon. In this study we review our recent experimental work on CaCO3 precipitation induced by two anoxygenic phototrophic bacteria (APB), Rhodovulum steppense A-20sT and Rhodovulum sp. S-17-65, and by cyanobacteria Gloeocapsa sp. f-6gl. These bacteria are representatives of two important groups of photosynthetic organisms present at the Earth surface both in the past and at the present times. The mechanisms of organomineralization deriving from APB and cyanobacteria activities are drastical…

Variational methods for the steady state response of elastic–plastic solids subjected to cyclic loads

2003

Abstract Solids (or structures) of elastic–plastic internal variable material models and subjected to cyclic loads are considered. A minimum net resistant power theorem, direct consequence of the classical maximum intrinsic dissipation theorem of plasticity theory, is envisioned which describes the material behavior by determining the plastic flow mechanism (if any) corresponding to a given stress/hardening state. A maximum principle is provided which characterizes the optimal initial stress/hardening state of a cyclically loaded structure as the one such that the plastic strain and kinematic internal variable increments produced over a cycle are kinematically admissible. A steady cycle min…

Effectiveness of BFRP confinement on the compressive behaviour of clay brick masonry cylinders

2020

Abstract This paper presents the results of an experimental and analytical study on the compressive behaviour of small clay brick masonry cylinders reinforced with a basalt fibre reinforced polymer (BFRP) composite. Fourteen cylinders, manufactured using two assembling schemes and confined using either one or two layers of BFRP grids, were tested under monotonic compression loading. Traditional strain measuring systems were integrated with digital image correlation (DIC) technique. The BFRP confined masonry cylinders showed a ductile behaviour characterised by a softening branch of the stress–strain curve. The experimental strains, strength, and full stress–strain curves were modelled using…

On the mechanical behavior of BFRP to aluminum AA6086 mixed joints

2013

The aim of this work is to analyze the possibility to join aluminum alloy AA6086 and composite laminates reinforced with basalt fibers, an innovative material which use is growing in several applications as an alternative to glass fibers. To this goal, three joining techniques were investigated: mechanical by Self Piercing Riveting (in the next called SPR), adhesive by co-curing technique and mixed in which the joining techniques (i.e. adhesive and mechanical) were combined. Two manufacturing technologies (i.e. hand lay-up and vacuum bagging) were used both to produce composite substrates and to realize co-curing adhesion between the substrates to be joined. Mixed joints were realized by in…