Effect of Bentonite Content and Hydration Time on Mechanical Properties of Sand–Bentonite Mixture

The bentonite is commonly used mixed with soils for groundwater retention and waste contaminant facilities. The incorporation of bentonite could significantly reduce hydraulic conductivity. In this study, the effects of bentonite content, hydration time and effective confining pressure on the static properties of a sand–bentonite mixture were studied using experimental and numerical methods. Firstly, a large number of drainage static triaxial tests on the sand–bentonite mixture with various bentonite contents were conducted. The test results show that the increase in bentonite content and hydration time leads to a slight decrease in shear strength and initial tangent modulus of the sand–bentonite mixture. The presence of bentonite reduces the shear shrinkage and dilatancy trend of the mixture. The cohesion of the mixture increases with the increase in bentonite content and hydration time, but the internal friction angle decreases correspondingly. The hydration of bentonite on the surface of sand particles changes the contact form between particles. The bentonite slurry between pores of the sand skeleton also affects the mechanical behavior of the sand–bentonite mixture. Then, a series of 3D discrete element models were established for numerical simulations of drainage static triaxial tests. The numerical model parameters were calibrated by experimental results. The meso-mechanism of bentonite content affecting the mechanical behavior was revealed according to the contact force distribution between particles. The research results are helpful to understand further the mechanism of bentonite on the mechanical properties of the sand–bentonite mixture.

Effect of Pebble Size Distribution and Wall Effect on Inner Packing Structure and Contact Force Distribution in Tritium Breeder Pebble Bed

In the tritium breeding blanket of nuclear fusion reactors, the heat transfer behavior and thermal-mechanical response of the tritium breeder pebble bed are affected by the inner packing structure, which is crucial for the design and optimization of a reliable pebble bed in tritium breeding blanket. Thus, the effect of pebble size distribution and fixed wall effect on packing structure and contact force in the poly-disperse pebble bed were investigated by numerical simulation. The results show that pebble size distribution has a significant influence on the inner packing structure of pebble bed. With the increase of the dispersion of pebble size, the average porosity and the average coordination number of the poly-disperse pebble bed gradually decrease. Due to the influence of the fixed wall, the porosity distribution of the pebble bed shows an obvious wall effect. For poly-disperse pebble bed, the influenced region of the wall effect gradually decreases with the increase of the dispersion of pebble size. In addition, the gravity effect and the pebble size distribution have an obvious influence on the contact force distribution inside the poly-disperse pebble bed. The majority of the contact force are weak contact force that is less than the average contact force. Only a few of pebbles have strong contact force that is greater than average contact force. This investigation can help in analyzing the pebble crushing characteristics and the thermal hydraulic analysis in the poly-disperse tritium breeder pebble bed.

Numerical study on contact force of paralleled beveloid gears using minimum potential energy theory

Using minimum potential energy theory and slicing method, a computational approach to calculate the magnitude and distribution of contact force for paralleled beveloid gear pair was proposed in this article. The theoretical tooth contact model was built based on spatial gearing theory to calculate the mesh parameters including the coordinates, normal vectors, and equivalent radius for meshing points. Then, the analytical contact force model of paralleled beveloid gear pair was derived based on minimum potential energy theory. Finite element contact analysis was conducted to verify the proposed model. Finally, the influences of macro-geometry design parameters on the contact force distribution were investigated. Results show that the pressure angle has a limited influence on the contact force distribution. The increase in helix and cone angles will observably increase the asymmetry of contact force distribution as well as the fluctuation of contact force distribution for a single tooth. A good correlation was obtained between the proposed analytical model and the finite element model for the distribution and magnitudes of contact force.

Dynamic Behaviour and Characteristics of Rubber Blade Car Performance

High technologies have helped so much in improving an optimizing the engine design and performance of the car. Improved isolation has helped to minimize the engine noise making other automotive part noises become more detectable. One of the noise sources are the wipers. When a wiper operates on a windshield, vibratory phenomena may appear due to flutter instabilities and may generate squeal noise. In order to obtain good wiping behaviour and characteristics, the rubber blade should be in complete contact with the glass and under uniform contact pressure while not generating vibration as it moves over the glass. A good wiping performance can be achieved by a proper design of the wiper structure as well as a good understanding of the mechanical behaviour of the rubber blade. The primary objective of this research is to investigate the dynamic behaviour and characteristics of rubber wiper blade performance in order to reduce the automotive windscreen wiper noise and vibration effects. In order to achieve the objective of this research, two types of wiper is used. One is hybrid type and second is conventional type. Then the behavior of wiper can be investigated. The force resistive sensor is used to measure the force distribution exerted on the windshield for the characteristics wiper noise for specific points. The obtain vibration data is processed by single-board microcontrollers. Behaviour movements of blade produce different vibration that can be investigated the maximum noise occurs on wiper blade operation using Uni-axial accelerometer A MMA7660. As a result, confirmation behaviour is shown the contact force distribution between rubber blade and glass is produce non-uniformly contact force and identical for hybrid type wiper and uniform contact force and not identical for conventional type wiper. In addition, characteristic of wiper rubber blade due to environment condition such as humidity, temperature and wiper stiffness are major factor in this research. As a conclusion, the results for behaviour of wiper blade depends on structural effect of the wiper blade related to the contact force distribution between the rubber blade and the glass. Secondly the characteristics of wiper rubber blade depends environment condition such as humidity and the temperature. The methodology is achievable to discovery the knowledge of dynamic behaviour and characteristics of wiper rubber blade in future.