Determination Of Dynamic Mechanical Properties Research Articles

Determination of Dynamic Mechanical Properties on Addition of Carbon Black-Nanosilica Hybrid Fillers in NR-SBR Blends with Special Reference to Power Transmission Belt Applications

Next to tyres, power transmission belts are one of the most complicated rubber products which is having a constant increase for demand in the market. Due to this high demand along with the requirement to meet certain special operating conditions, it is necessary to improve the belt properties continuously. In the last few decades, nanotechnology evolved as a suitable method for enhancing the properties of various rubber products without impacting the environment. Nanofillers which are having unique morphology along with excellent properties help to reduce the dependency in petroleum products and in turn make the products more sustainable. Even though, studies related to the usage of nanotechnology in the power transmission belt division are very limited. So, in this study, the effect of nanosilica on the dynamic mechanical properties of the natural rubber- (NR-) styrene butadiene rubber (SBR) blends is thoroughly studied with special reference to power transmission belt applications. The developed composites were analysed to ensure the rheological, mechanical, and morphological properties in comparison with the controlled samples. The nanosilica-based belt properties were analysed in reference with regular carbon black-filled belts, and a 15% improvement in belt life was obtained for newly developed belts.

Determination of dynamic mechanical properties of silica aerogel by resonance and non-resonance method

Silica aerogel has great potential in aeronautics, building construction, and offshore oil transportation. The dynamic mechanical properties of silica aerogel were measured by the resonance and non-resonance method. The results of the two methods were compared. While the Young’s modulus coincided well, the loss factor had big difference. To explain this phenomenon, the sensitivity of the two methods was analyzed. It shows that the loss factor determination of low-loss materials by the non-resonance method is quite sensitive to the experiment uncertainties. This probably results in the loss factor difference between the two methods.

A Comparison of Different Methodologies for PVB Interlayer Modulus Characterization

The proper measurement and interpretation of modulus data for glass laminate interlayers can be quite complex. The development of master curves using different deformation modes and the preparation of the samples for measurement can significantly affect the results. International standard ISO 6721, determination of dynamic mechanical properties, uses modulus as a primary criterion for method selection. The shear modulus of polyvinylbutyral (PVB) materials varies to a great extent, e.g. 1 – 400 MPa, over the temperatures and durations encountered for glass laminates in a building. We have evaluated the use of tensile and plate-plate geometries for a regular and a high rigidity (“structural”) PVB interlayer material, as well as torsion geometry for a structural PVB interlayer material. In some cases, datasets from different sources have been compared. This paper will discuss the results we obtained using different methodologies, and explore the effect with regards to positioning of the interlayers in the “stiffness families” and the associated shear transfer coefficients as in draft European norms prEN 16612 and prEN 16613.

Determination of dynamic mechanical properties of carbon black filled rubbers at wide frequency range using Havriliak–Negami model

Abstract An accurate dynamic mechanical model plays a vital role in the engineering application of rubber-like materials. Though many researchers have done work on these models, it is still difficult to fit the model's parameters via dynamic mechanical thermal analysis (DMTA) data, especially for Havriliak–Negami (HN) model. A methodology is proposed to determine the parameters in HN model. The DMTA data of carbon black filled rubber (CBFR) NR100N550 is utilized to verify the methodology in this paper. The time–temperature superposition principle (TTSP) is applied to investigating the viscoelastic properties of CBFR NR100N550 at wide frequency range. The experimental results show that the proposed methodology could be applied to obtaining parameters in HN model. HN model is able to model the dynamic mechanical properties of carbon black filled rubbers at wide frequency range, which are correlated with the chemical structure of the polymers.

Investigation of Sample-size Influence on Tensile Test Results at Different Strain Rates

The paper deals with the determination of dynamic mechanical properties of steel sheets by the miniature testing technique. Several materials were investigated, namely S235, S355 and 1.4301. The newly developed micro-tensile test (M-TT) allows local mechanical properties measurement which can be successfully used for example for weld heterogeneity determination. Furthermore, due to small size samples (tensile sample gauge section dimension of 0,5x1,5x3mm), much higher strain rates can be attained using relatively slow loading velocities in comparison to standard dynamic tests resulting in high results consistency thanks to significant reduction of the oscillations which are typical for common high strain rate tests. The results obtained from M-TT and standard tensile tests were compared.

Determination of dynamic mechanical properties of engineering thermoplastics at wide frequency range using Havriliak–Negami model

AbstractUsing Havriliak–Negami (HN) model of time–temperature superposition, dynamic mechanical properties for two thermorheologically simple engineering thermoplastics, viz., polyether ether ketone (PEEK) and polycarbonate (PC) were determined. Calculations have been made with respect to (i) temperature‐independent HN parameters from dynamic mechanical analysis (DMA) and (ii) activation energies of the deformation processes involved. Viscoelastic properties, over a wide frequency range, were predicted from the HN model, which were further correlated with the experimentally determined quantities and chemical structure of the polymers. The mathematical calculations were done using Matlab® software. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 677–683, 2006

Determination of dynamic mechanical properties of metals from single pendulum scratch tests

This paper describes evaluations of dynamic mechanical properties of typical metals (Al, Cu, Ti, Ni, Co, and Mo) with single pendulum scratch tests. The curve fitting method with a polynomial has been used to calculate the geometrical parameters of the scratch track during the scratching process. The methodology and analytical modeling are developed for determining a series of mechanical properties, such as elastic modulus, shear modulus and cohesive strength of materials, with the help of calibrations to those of these metals. These parameters are effective to describe the dynamic mechanical properties of massive materials and modified surfaces of materials. Using these methods, the mechanical properties of plasma sprayed Ni–ZrO 2 coatings are determined.

A laser-induced ultrasonic probe of the mechanical properties of aligned lipid multibilayers

The recently developed laser-induced phonon spectroscopy (LIPS) technique is applied to the determination of dynamic mechanical properties of aligned dilauroylphosphatidylcholine (DLPC) multibilayer arrays containing 2 and 20% water by weight. Sample excitation by two crossed 100-ps laser pulses generates a longitudinal ultrasonic wave whose wavelength depends on the crossing angle. In these experiments, the acoustic wave propagates parallel to the bilayer planes. The ultrasonic velocity and attenuation are monitored through the diffraction of a variably delayed probe pulse by the acoustic grating. The velocity measures the lateral area compressibility of the bilayers, while the attenuation is related to the viscosity. Velocities obtained in the gel and liquid crystal phases are compared with those found previously using Brillouin scattering. The acoustic attenuation is shown to be an order of magnitude more sensitive to the gel-liquid crystal phase transition than the velocity. The lipid area compressibility and viscosity of DLPC-20% water multilayers with and without 100 mM CaCl2 are found to be identical within our experimental error.

Constitutive laws of materials in dynamics—outline of a programme of testing on small and large specimens for containment of extreme dynamic loading conditions

A sound foundation of stress and/or strain criteria for the mechanical design of fast breeder reactor structures capable of bearing extreme dynamic loading conditions, passes through the experimental determination of dynamic mechanical properties of materials in end-of-life conditions with respect to the damaging processes to which the structures are submitted. Calculation codes must be implemented by constitutive equations describing the dynamic mechanical response of the materials, without the knowledge of which any calculation code is liable to important inaccuracies which provoke the use of high safety coefficients and, often, the uncertainty as to the effective capability of the structures to withstand the accidental loads. The results of a screening programme of dynamic tensile tests performed on AISI 304 and AISI 316 austenitic stainless steels using small specimens (7 mm 2) showed that the dynamic response of such steels at temperatures of 400 and 550°C is not univocal, passing from a substantial dynamic hardening behaviour to a dynamic softening behaviour, probably due to residual microstructural differences caused by the transformation processes. From the discussion of the results obtained, follows the development of a testing programme on small (up to 20 mm 2 cross section) and large specimens (up to 5000 mm 2 cross section) focused on: (i) developing and calibrating dynamic constitutive equations founded on basic physical aspects, for uniaxial and multiaxial loading conditions under particular deformation and loading histories; (ii) verifying in dynamics the existing yielding criteria, hardening rules and failure theories; (iii) investigating by means of a high-load apparatus (5 MN) the influence of near real-size thickness, welding, defects and notches, on dynamic strength and deformation capability of large reactor structures.

Isophasic transitions in polytrifluorochloroethylene

AbstractThrough determination of dynamic mechanical properties (sound velocity and damping factor) over the temperature range from −160 to 200°C. and frequency range from 4 to 16 kcycles/sec. evidence is found for the existence of two isophasic transition temperatures in polytrifluorochloroethylene: one at −58°C. and the other at 50°C. Both transitions are associated with motion in the main chain of the polymer, which is first excited at −58°C. for the molecular segments which are more freely rotating (because they are located near network defects) and at 50°C. for the majority of the chain elements in the amorphous regions. The transition point at −58°C. is regarded as the glass transition temperature for polytrifluorochloroethylene. The experimental results are discussed on the basis of the structure of the polymer examined, and a comparison is made between dynamic mechanical data and data obtained by measurements of specific volume, nuclear magnetic resonance, and dielectric losses.