Hedi Hassis | University of Tunis El Manar (original) (raw)

Papers by Hedi Hassis

An experimental study of the e!ects of cavitation was carried out through an analysis of cavitati... more An experimental study of the e!ects of cavitation was carried out through an analysis of cavitating Butter#y and Monovar values. Focus is particularly placed on both unsteady pressure and acoustic pressure #uctuations. In this paper, the e!ects of cavitation on local #uctuation pressure (turbulence), acoustic propagation (damping and sound velocity), resonance frequencies and level of noise are presented.

HAL (Le Centre pour la Communication Scientifique Directe), Nov 2, 2015

HAL (Le Centre pour la Communication Scientifique Directe), May 17, 2016

District heating networks are commonly addressed in the literature as one of the most effective s... more District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.

Machine Dynamics Research, 2016

Book Publisher International (a part of SCIENCEDOMAIN International), Mar 7, 2022

European Journal of Mechanics - A/Solids, 2001

ABSTRACT A two-dimensional model that takes into account the 1-D behaviour of the cord, is presen... more ABSTRACT A two-dimensional model that takes into account the 1-D behaviour of the cord, is presented for the analysis of cord-composite plates. The cords are represented by an equivalent geometrical surface having the mechanical characteristics including bending property and the coupling between twist-extension. The non-symmetrical position of the cord within the cord-composite plate is also considered. Examples of cord-composite plates consisting of one central layer, two symmetrical layers, and two non-symmetrical layers are studied, and the results are presented to illustrate the coupling effects on the mechanical behaviour.

The study aims at comparing the results of different probabilistic methods such as the perturbati... more The study aims at comparing the results of different probabilistic methods such as the perturbation method, Spectral Stochastic Finite Element Method (SSFEM)

A new practical engineering methodology for the analysis of structures under cyclic loading is pr... more A new practical engineering methodology for the analysis of structures under cyclic loading is proposed in this work. A new anisotropic fatigue damage model is developed. The evolution of material properties degradation depends on a failure criterion and its gradient. The anisotropic material degradation will guide the damage propagation. The propagation of damage is mainly depending on the ridges of the criterion’s “surface” (zero gradients). The proposed approach can describe the initiation and propagation of the damage until the structural failure under fatigue loading. For each finite element, a non-homogeneous anisotropic distribution of material properties are associated. Schematically, it seems like a material “surfing” on the criterion’s “ surface” and damages follow the crest of the criterion’s “surface” (level and gradient). A global approach criterion, based on invariants of the stress tensor, is adopted. The reduction of material properties is assigned to a number of cyc...

IOSR Journal of Engineering

In mechanics, as in many scientific domains, information and data can be:deterministic (certainty... more In mechanics, as in many scientific domains, information and data can be:deterministic (certainty known or with error-safety coefficient),probabilistic (random with known probability distribution),possibilistic (random known with an uncertainty factor on the reliability of the information. Parameters change in a known range, but the probability is unidentified).The probabilistic mechanical approaches aim to give an estimation of the solution when the information on the parameters of analyzed problem is uncertain.For some mechanical problems with probabilistic parameters, a constraint to be satisfied is added. In engineering design, the reliability analysis is an example of such constraint.In this paper, and for static probabilistic-reliability analysis, an approach reducing the size of numerical computing is proposed. It will be validated on static discrete and continuous systems having probabilistic parameters.

Mechanics of Composite Materials

A mortar reinforced with long unidirectional alfa and sisal fibers was considered. Laminated mort... more A mortar reinforced with long unidirectional alfa and sisal fibers was considered. Laminated mortar specimens with different fiber volume fractions were prepared, and their mechanical properties were investigated. The optimum fiber volume fraction was found to range between 0.8 and 1.1% and depended on curing conditions. In the case of alfa fibers, the flexural strength of mortar specimens increased by about 27%. It is concluded that alfa fibers can be an alternative to synthetic fibers.

International Journal of Solids and Structures, 2015

Within the framework of fully nonlinear fracture mechanics under plane deformation conditions, bo... more Within the framework of fully nonlinear fracture mechanics under plane deformation conditions, boundary value problem equations for the V-notch vertex problem in an incompressible Mooney-Rivlin material are deduced. Using an asymptotic procedure, the deformation, the Lagrange multiplier and stress fields near the notch vertex are computed and their principal properties are illustrated. First, it is shown that the singularity order depend on the V-notch angle. Second, a change of the singular term for a critical angle was revealed and a logarithmic singular term appears. Based on the results obtained, the deformed V-notch vertex lips near the tip was drawn. The V-notch vertex is shown to open, but not necessary in a symmetric manner. Analysis of the Cauchy stress tensor shows that the component σ 22 dominates the stress field. Some discrepancy with the linear theory have emmerged.

International Journal of Engineering Science, 2015

Abstract The anti-plane shear transformation corresponding to a bimaterial wedge problem is studi... more Abstract The anti-plane shear transformation corresponding to a bimaterial wedge problem is studied within the framework of finite elasticity. Two wedges of arbitrary angles are assumed to be incompressible hyperelastic Neo–Hookean materials, and have a common perfect interface and a traction free surface. The resolution of the boundary value problem near the vertex of a bimaterial wedge by means of asymptotic procedure leads to an eigenequation connecting wedges angles and materials properties. Results proved that, contrary to linear elasticity predictions, it is needed to extend development to higher orders because of their contribution in stress singularity.

pphmj.com

This paper describes a pushing-cut process of two stacked polycarbonate (PC) sheets. The cutting ... more This paper describes a pushing-cut process of two stacked polycarbonate (PC) sheets. The cutting line force of the facet (single line, two-line) blade on the stacked PC sheets was measured and the cutting deformation of the upper PC sheet was observed with a CCD camera in order ...

The vibration of post-buckled fluid-conveying pipe made of functionally graded material is analyz... more The vibration of post-buckled fluid-conveying pipe made of functionally graded material is analyzed. The pipe material properties are assumed to be graded in the thickness direction according to power-law distribution. An exact solution is obtained for the post-buckling deformation of the fluid-conveying functionally graded pipe with various boundary conditions. The linear vibration problem is solved around the first buckled configuration and the natural frequencies of the three lowest vibration modes are obtained. The influences of power-law exponent, initial tension, fluid density and fluid velocity on the static deflection and free vibration frequencies are studied.

Journal of Sound and Vibration, 1998

An Integral Representation Formulation (IRF) has been developed to solve some one-dimensional pro... more An Integral Representation Formulation (IRF) has been developed to solve some one-dimensional problems: acoustic problems in pipes, longitudinal and transverse vibrations of pipes, including mean flow effects. The fluid-structure interaction is analyzed in the case of a straight pipe. The fundamental solutions and the set of equations governing problems are determined in each case. To demonstrate the efficiency and the simplicity of the use of the IRF method for one-dimensional problems, examples are presented.