Research Activities

·     Experimental and Numerical Study of thermal contact parameters during glass forming and hot stamping processes.

An experimental device is designed and developed to estimate the thermal contact resistance at the part/tool interface during glass forming and hot stamping processes as shown in the figure. Samples and tools are thermally instrumented with thermocouples type K sheathed with silky glass, forming heat flux-meters in the most critical locations in the tools. At the part boundary, thermal conductance is calculated using convective/radiation modeling of both phases: approach and forming. At the contact interfaces, thermal contact resistances RC are estimated experimentally through a non-linear 1D inverse technique founded on sequential method of Beck.

 

·     Analytical modeling and numerical analysis of the mechanical behavior of textile composites

This project concerns the analysis of the ultimate strength under tensile and compressive loading for textile composites and the determination of the permeability fibrous composites, which enhance the optimization of the manufacturing of composites using RTM.
 
 
·   Development of algorithm for computational mechanics
This domain concerns mainly material forming calculations and fluid-structure interaction problems. A “Mutli-Mesh Multi-Physic” method is developed and integrated in the software Forge3. An “intermediate Mesh Method” is developed to couple fluid and structure codes, it is utilized to couple the software Fine Marine to the “ZorgLib” a library developed to carry out dynamic calculation.
 
   
 
    ·      Parkinson’s Disease: Vibration Absorber for Hand Tremor

In Lebanon, there are 13,886 patients suffering from Parkinson disease. Parkinson disease (PD), a widely diagnosed progressive degenerative disorder of the basal ganglia, is characterized by the loss of dopaminergic neurons in the substantia nigra. The typical symptoms of PD include resting tremor, rigidity, bradykinesia, and postural instability.

Parkinson's disease is a degenerative disorder of the central nervous system that often impairs the sufferer's motor skills, speech, and other functions. This disease is well known around the entire world. Patients that suffer from this disease especially the youth are disabled to live normally. The main goal of the current project is to develop a non-invasive control system, as illustrated in the figure below, which could effectively suppress Parkinson’s disease tremor of the human arm undergoing involuntary rhythmic oscillations. Development of such a medical system will help PD patients to restore lost functions caused by the symptoms of the disease and improve their quality of life.

      ·       Proper Generalized Decomposition method applied to the fatigue of polymer under different loading

To deal with the viscoelasticity of polymers, we have to consider a continuous distribution of relaxation times. Usually, 50 relaxation times are used to approximate a discrete spectrum with six decades [2]. The evolution law associated to each internal variable consists in a differential equation with respect to time. To simulate this behavior, we have to solve simultaneously the mechanical equilibrium equation and fifty evolution laws.

From a numerical point of view, the use of classical finite element method leads to a large computation time linked to the incremental scheme especially in the case of nonlinear differential equations. Namely, at each time step, we have to solve 50 equations for each Gauss point in the case of viscoelastic polymer. In the case of linear differential equations, analytical solutions allow a quick estimation of the evolution of the internal variables at each time step. Otherwise, if the differential equations are strongly nonlinear, their solving necessitates considering another temporal scheme for example an adaptive Runge Kutta. Let us note that these numerical issues are particularly adapted for long relaxation times. To predict viscoelasticity of polymers under cyclic loading, we have to consider another time linked to the loading. The time steps of the integration scheme will be more constraints.

Moreover, polymers material don’t reach a stabilized cycle after few fatigue cycles like metals but cycle evolves slowly under the effect of creep at average stress mainly due to the strong coupling with temperature. It has been shown that 200 cycles are not enough to reach the stabilized cycle for polypropylene under multiaxial fatigue. Therefore, the temporal domain becomes very large which induces a very high computation time with a classical finite element method.

In this project, the PGD will be extended to the case of a Viscoelastic / Thermoviscoelastic mechanical problem with a large number of internal variables and a large spectrum of relaxation times.




·     Vehicle Dynamics Control Systems