A Modified Arcan Fixture (MAF) was developed to study the biaxial mechanical behavior of fiber reinforced composites. The MAF was calibrated compared with standard ASTM tests for an epoxy/twill ...woven-ply laminate. Material properties obtained with ASTM tests are implemented in ABAQUS to find the optimal notch radius that creates the most uniform stress state in gauge area. The optimized configuration of Arcan specimen was adopted to design the entire fixture numerically in preload and load steps to avoid plastic deformation. Stress concentration factor was considered in Arcan specimen under tensile loading. Biaxial experimental data for woven-ply composite in different loading angles was obtain with the MAF. Failure modes under biaxial loading show that fibers rotated towards the principle tensile direction and failure was caused by excessive stress which reached fiber limit. The ultimate shear strength corrected by considering the fiber rotation effect are in good agreement with ASTM standard results.
• A new redesigned Arcan fixture, an alternative to tubular, off-axis specimens, was proposed to conduct biaxial loading testwith following advantages:•It is easier to obtain biaxial stress state by using a flat Arcan specimen compared to tubular specimen and cruciform specimen (fabrication and sophisticate clamping system).•The clamping jaws prevented pre-damage and shear out observed around connecting holes presented in literatures.•The simple quick release structure permit to conduct a large number of tests efficiently.•Combined tension(compression)/shear monotonic and fatigue tests can be conducted.•The biaxial loadings can be applied easily with loading angle changed by a step of 15.•Equipped with guide units to insure the in-plane stress states during quasi-static loading or fatigue loading and anti-buckling under compression.•The entire fixture and Arcan specimen were optimized in Finite element analysis.•A full material property card obtained with the MAF has good agreement with ASTM standard results.•Stress concentration induced by V-notch Arcan specimen was corrected in elastic range under tensile loading.•The effect of fiber rotation under shear were considered to described the non-linear behavior.•The mechanical behavior of a 2D woven composite in combined shear/normal loading configurations as well as under tensile and shear was investigated.•Contributes biaxial experimental data for 2D woven composites.
► γ-treatment of carbon fabric led to significant changes in surface topography. ► γ-treatment of fabric led to the enhancement in the fiber–matrix adhesion. ► Tensile strength of the fiber decreased ...with increase in irradiation dose. ► Almost 60% improvement in ILSS of composites was observed. ► The treated composites showed higher wear resistance and lower μ in adhesive wear mode.
Fiber–matrix interfacial bonding plays a critical role in controlling performance properties of the composites. Carbon fibers have major constraint of chemical inertness with the matrix and need surface treatment to improve the adhesion with the matrix. In this work, gamma irradiation technique with varying doses (100–300
kGy) was employed to carbon fabric (CF) to develop composites with polyetherimide (PEI) matrix based on impregnation method followed by compression molding. Composites were characterized for interlaminar shear strength (ILSS) and adhesive wear studies against mild steel disc under various loads. Improvement in the friction and wear properties was correlated with the improvement in ILSS as a result of CF treatment. Higher the dosing, higher was the enhancement in ILSS and tribo-performance of composites. Fourier transform infrared spectroscopy (FTIR) indicated inclusion of functional groups (mainly carbonyl). SEM studies on fibers indicated roughening of the surface as a consequence of treatment. Both these factors were thought to be responsible for enhancing the fiber–matrix interface. For in depth analysis, various techniques such as fiber tension test, adhesion test and Raman spectroscopy analysis of CF were also exploited.
•Effect of surface laser treatment on the magnetic properties of GO laminations.•Investigating different types of laser treatments: irradiation, scribing and ablation.•Power loss reduction and ...apparent permeability improvement under a laser scribing with short pulse.•Induced thermal stress, heat-affected zone and groove depth as a function of laser energetic parameters.•A dynamic magnetic hysteresis model (lambda model) related to the dynamic loss and the apparent permeability.
Electromagnetic components mostly incorporate soft magnetic materials used as flux multipliers. Hence, any reduction in iron loss of the magnetic core yields in saving energy. Among the techniques, the local laser treatment is a non-contact method applied for 180° domain refinement (Patri et al. 1). The present study reassessed the impact of laser treatment on the magnetic properties of grain oriented silicon steels. Various laser pulse widths are used: an ultra-short pulse laser mainly adapted to the ablation process and a long and short pulse durations used for both irradiation and scribing processes 2. The power loss is measured with a Single Sheet Tester (150 × 150 mm2). Each type of treatment resulted in a power loss reduction of 15–35% at peak induction 1.5 T and frequency 50 Hz. However, only the scribing and the ablation improved also the apparent permeability. In this work, the laser energy parameters are used to estimate the laser impact on the heat affected zone, the groove depth, the induced thermal stress, and on the internal properties of a magnetic behavioral model: static permeability and dynamic magnetization property 3.
•New direct life prediction method is proposed for FRP material.•Numerical algorithm is described.•Evaluation of the material parameters are shown on the performed experimental data.•The method ...allows to account the load-ration effect.•It is validated on different ply-stacking.
In this paper, a direct computational method of life prediction for fibre-reinforced polymers (FRP) is developed. This approach is based on a simplified direct method (SDM) which allows to predict the life from the stabilized damage state. The SDM is extended to the case of anisotropic continuous damage mechanics of FRP. It is shown that damage processes in composite material subjected to fatigue load can reach stabilized damage state. Damage state and thermodynamic forces associated with damage mechanisms at the stabilized state are related to life. Experimental validation was done on the standard glass-fibre/epoxy angle-ply and cross-ply laminate plates subjected to fatigue loading with different load ratios (R=0.1,0.5).
A meso-scale material modeling of the fiber-reinforced polymer composites is presented. This model is based on coupled anisotropic viscoelasticity–viscoplasticity with anisotropic continuous damage ...mechanics. The constitutive equations are derived for three-dimensional statement and integrated implicitly by using return-mapping algorithm. Viscoelasticity model implies time dependent material properties. Viscoplasticity model is based on modified Hoffman criterion with combination of the Perzyna model. Anisotropic damage model is based on extended three-dimensional damage model. Developed material model is implemented in ABAQUS/Standard and is applied for modeling glass and carbon fiber laminate composite plates with various stacking sequences. Obtained results are in high agreement with already published experimental data.
Chemical inertness and hence limited wettability of carbon fibers (CF) with a selected matrix is the major problem for exploiting its full potential as reinforcement. Oxidation of CF with nitric acid ...is a classical method for treatment of CF which increases oxidative groups on fiber surface leading to enhanced adhesion with the matrix, but at the cost of damage to the fibers leading to reduction in strength. Thus the treatment has to be for optimum time to strike a balance between these opposite effects so that the composite will have best combination of performance properties. In depth studies on this aspect, however, are not reported especially in tribological studies. Hence nitric acid treatment was employed to carbon fabric for various time intervals (15–180
min). Eight composites with untreated and acid treated fabrics were developed based on polyetherimide (PEI) matrix and evaluated for mechanical and abrasive wear properties. It was observed that 90
min treatment time was ideal one to achieve maximum possible enhancement in strength and tribological properties. Fiber–matrix adhesion was improved due to inclusion of oxygenated functional groups as supported by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and increased surface roughening of fibers as supported by scanning electron microscopic (SEM) studies.
•Non-destructive measurement technique for magnetic-induced strain.•Development of an inverse dynamic model for magnetic strain identification.•Effect of the mechanical damping in electrical steels ...on the magnetic strain.•Distinction between the apparent strain and the magnetic-induced strain.•Effect of the non-linear magnetization on the mechanical response.
Magnetic induced strain is an important source of vibration in electromagnetic components and electrical machines. This magneto-mechanical behavior is identified using a non-destructive experimental technique that consists in measuring in a Single Sheet Tester the time dependent acceleration at the free end of a fixed-free magnetic sheet and its corresponding magnetic field and induction signals. The determination of this property in the longitudinal direction is investigated using an inverse application of the longitudinal vibration equation. The strain dependence on the exciting frequency as function of the resonance frequency is also evaluated. The apparent strain that includes the inertia effect is distinguished from the magnetic-induced strain. Both strains are identified and analyzed for different frequencies lower and higher than the sample’s natural frequency. We also investigated the effect of excitation’s harmonics on the mechanical response.
This work investigates a 2-D vector field behavioral model to describe the anisotropic magnetic permeability and losses in Grain-Oriented Electrical Steels (GOES) within quasi-static and ...magneto-harmonic working conditions. The model includes the an-hysteretic magnetic field driven by the total anisotropy, the coercive force responsible for the quasi-static hysteresis losses, and the dynamic damping eddy field responsible for the extra losses. Each field contribution requires the definition of a tensor property whose diagonal and non-diagonal coupling components are experimentally identified as a function of the flux density magnitude <inline-formula> <tex-math notation="LaTeX">B </tex-math></inline-formula> and its angle <inline-formula> <tex-math notation="LaTeX">\theta </tex-math></inline-formula> with the Rolling Direction (RD). The static behavior is identified at low frequency and the dynamic one takes the frequency-dependent field diffusion into account. Diagonalization tools reveal main characteristic magnetic axis for the separate properties with deflections at the macroscale.
► HNO3 treatment (30–180min) to carbon fabric led to changes in surface topography. ► Treatment proved beneficial for adhesive wear performance of composites. ► 90min treated CF composites (C90) ...showed highest strength properties. ► Highest wear resistance and lowest μ was observed for C90 composites. ► A good correlation was observed for wear resistance and ILSS of composites.
Oxidation treatment with concentrated HNO3 was employed to the carbon fabric (CF) for various time intervals (30–180min) to observe the effect of treatment on two simultaneous processes involved viz. improvement in its adhesion with the matrix and reduction of fiber strength which in turn is responsible for change in the performance properties of composites. Seven composites with untreated and acid treated CF were developed based on the polyetherimide (PEI) matrix and evaluated for adhesive wear properties under various loads (200–600N) against mild steel disc. 90min treated CF composite indicated the best tribological properties and showed 30% reduction in specific wear rate (K0) and 23% in coefficient of friction (μ) respectively at 600N load. Treatment beyond this time proved detrimental for improvement in properties. Field emission scanning electron microscopy (FE-SEM) showed increase in roughness with treatment time, while atomic force microscopy (AFM) studies indicated substantial increase in roughness value. Scanning electron microscopy (SEM) of worn surfaces supported the wear mechanisms and improvement in adhesion between fiber and matrix.
The purpose of this article is to study the impact of surface laser treatments with ultra-short pulses (USPs) (femtosecond laser) on the magnetic properties of grain-oriented electrical steels ...(GOESs) using the two-temperature model for the ablation process and the magnetic loss separation model of Bertotti. We demonstrated that the hysteresis and excess loss coefficients behave differently depending on the type of laser treatment and its pulse duration long pulse (LP), short pulses (SPs), and USP. We also presented the adjusted models to estimate the impact of the USP on the sheet surface in terms of laser energetic quantities; more precisely, the groove depth, the plasma maximum temperature, and the peak surface wave pressure were estimated, relative to its nominal value. The latter physical impacts of laser pulses were then correlated with Bertotti's loss coefficients: the static hysteresis loss coefficient and the excess loss coefficient. The laser process is not always able to reduce simultaneously both loss contributions. Thus, a compromise must be found to optimize the process. The variation of the flux density level as a function of the applied magnetic field was measured with a single sheet tester (SST) under a one-directional field parallel to the rolling direction. From these measurements, we deduced the whole power loss contributions. Results showed that an optimization of the laser's parameters ensured an iron loss reduction at 50 Hz up to −30% for an induction below 0.5 T and a percentage close to −15% for an induction above 1.5 T.
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