1,721,078 research outputs found
Ultimate behaviour of adhesively bonded FRP lap joints
Full text linkThis paper deals with a numerical investigation on double-lap and symmetrical single-lap joints subjected
to shear/bending moment and axial force. The analysis has been developed using the theoretical
model proposed by the author in [Ascione F. Mechanical behaviour of FRP adhesive joints: a theoretical
model; 2007].
The mechanical behavior of the adhesive is modeled through two sets of independent interfacial
springs capable of characterizing the normal and transversal interactions, respectively. The adherents
are modeled following the hypotheses of the beam technical theory. The mathematical model is based
on two fundamental hypotheses: the possibility to separate the shear-flexure problem from the extensional
one; the total fracture energy is additionally broken down in a term relative to mode I of fracture
(opening) and in a term relative to mode II of fracture (sliding).
Five dimensionless parameters which influence the design problem of the joints are identified. Several
examples of the ultimate domains of the interface between the adherents are also presented as well as
comparisons with some results reported in literature
A preliminary numerical and experimental investigation on the shear stress distribution on multi-row bolted FRP joints
Full text linkThe first results of a numerical and experimental investigation on the shear forces distribution in a bolted joint made entirely from FRP materials are presented. It is also proposed an experimental equipment for investigating the strains and stresses distributions around the holes of the connection as well as the bearing stresses at the interface between plate and steel bolt. A good agreement between numerical and experimental results allows to use the proposed testing set-up for analysing the bearing failure of several joint configuration with different lamination scheme, geometry and type of load
The influence of adhesion defects on the collapse of FRP adhesive joints
No full textIn this paper, the debonding of adhesive double-lap joints between FRP adherents is analyzed with regard
to the influence of an initial adhesion defect on their ultimate capacity. The analysis is carried out by using
the interface cohesive models proposed by Hutchinson & Suo, Xu & Needleman, and Camacho & Ortiz.
The mechanical model utilized takes into account the shear deformability of the adherents and the
coupling effects between axial and shear/flexure behavior. The model is non-linear due to the hypothesis
of a cohesive interface adopted for the adhesive layer. The numerical results, obtained via finite element
analysis, have highlighted that the model of Hutchinson and Suo is less conservative than the other two
and that joints subjected to axial forces are less sensitive to initial adhesion defects than ones loaded by
both axial and shear forces
Adhesive lap-joints: a micro-scale numerical investigation
Full text linkA micro-scale numerical investigation on the response of adhesive lap-joints between FRP adherents has been performed. Such an analysis allows to compare the prediction of classical theories with those ones obtained by the proposed approach, showing relevant differences in terms of ultimate behavior
Influence of initial geometric imperfections in the lateral buckling problem of thin walled pultruded GFRP I-profiles
No full textThis paper aims at investigating the influence of some typical manufacturing geometric imperfections on the pre-buckling behaviour of transversally loaded GFRP I-beam. One dimensional mechanical approach is proposed by modelling each panel of the cross section as a Timoshenko rectangular beam. In addition to the usual displacement and rotational degrees of freedom used in conventional beam models, few extra degrees of freedom are introduced in order to account for sectional distorsions.
The model is based on the common assumptions of linear elasticity with small strains and moderate rotations.
Two kinds of manufacturing imperferction are taken into account: minor axis out-of-straightness and web/flange planes non-orthogonality the latter representing a particular feature of the present model.
Numerical analyses, developed via finite elements, show that such kind of imperfections can significantly influence the pre-buckling behaviour making deformability requirements a fundamental design rule
Mechanical behavior of FRP adhesive joints: A theoretical model
Full text linkIn this paper a mathematical model for studying the equilibrium problem of adhesive joints between FRP
adherents is presented. In particular, double and single-lap joints, both in the case of normal and shear/
flexure stresses are considered. The problem is non linear due to the cohesive constitutive law adopted
for modeling the interface. On the contrary, the adherents are supposed to be indefinitely linear elastic.
The possibility to uncouple the problem of shear/flexure from the extensional one, as well as disregard
the mutual effects between the normal and tangential stresses acting at the joint interfaces is also
assumed. As highlighted in literature, this hypothesis allows results which are sufficiently correct from
a technical perspective when the mechanical characteristics of the adherents are almost the same, as supposed
in the present paper. Within such a framework it is possible to trace back the examined equilibrium
problems to those of simpler auxiliary structural schemes. A simple and efficient iterative
procedure for solving the aforementioned problems is also proposed
On The Shear Forces Distribution in Double Lap Bolted Frp Joints:Numerical and Experimental Investigations
Full text linkMechanical models for predicting the strength and stiffness of a beam-to-column adhesively-bonded connection between pultruded profiles
No full texthis paper presents two simple analytical expressions to predict the strength and stiffness of an adhesive beam- to-column connection between glass pultruded profiles (GFRP) subjected to shear and bending loads (vertical load applied at the free end of the beam). The joint configuration is characterized by a tubular column made of a commercially available hollow profile with a square cross section (90 mm ×90 mm ×8 mm) and two U-profiles (150 mm ×45 mm ×8 mm) arranged in the form of a built-up beam. The mechanical behaviour of this type of connection is governed by shear and bending stresses acting on the beam, with the latter becoming torsional stresses inside the adhesive layers and responsible for the failure of the connection. Regarding the strength prediction, a simple mechanical model based on the scheme of a single lap joint subjected to a traction force is presented. While, for the stiffness prediction, a simple formula for evaluating the adhesive layer deformability is proposed. With the latter, and by means of the Principle of the Virtual Power, the vertical displacement (corresponding to the vertical load applied) is evaluated and, consequently, the stiffness of the joint predicted. A comparison with the experimental results available in current literature has made it possible to verify the effectiveness of the proposed formulations which involve relatively few geometrical and mechanical parameters
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