LONGITUDINAL COMPRESSING AND SHEARING PROPERTIES OF SILAGE CORN STALK IN NORTH CHINA PLAIN

During silage harvesting, silage corn stalk is compressed by a feeding device and fed into the shearing device to be sheared into qualified segments to make silage fermentation easier. To optimize the working quality of the existing silage harvester and reduce energy consumption, it’s necessary to make a comprehensive analysis of the longitudinal compressing and shearing properties of the silage corn stalks and get a reliable shearing model. According to the different structural properties of the silage corn stalks, the main factors affecting the shearing energy consumption and their levels were obtained by compressing and shearing tests on internodes and nodes in this paper. The results of three-level and three-factor experiments showed that the overall shearing energy consumption for nodes was much higher than that for internodes. Compressing the silage corn stalk to some extent before shearing at the loading direction of 0° and lower shearing speed was beneficial to saving energy during the process of shearing off the silage corn stalk. The reduced energy requirements of the silage corn stalk could be exploited advantageously to present new reference for the feeding and cutting mechanisms of silage harvester. The research results can provide a reference for silage corn harvesting.

Physical and Mechanical Properties of Kenaf (Hibiscus cannabinus L.) Stems at Varying Moisture Contents

The physical and mechanical properties of Nigerian variety Kenaf stems Ibadan Local were studied. Plant height was ranged from 224 cm to 327 cm and maximum stem diameter was ranged from 15 mm to 50 mm. The mechanical properties revealed that maximum cutting force and shearing energy were 1778.62 N and 10.20 J, respectively for 37% moisture content while it was 742.67 N and 3.74 J for 77% moisture content. The Young’s modulus ranged from 60.04 – 266.80 MPa. The greater shearing energy was obtained at the base of the stem.

Design and Test of Double-Cutterbar Structure on Wide Header for Main Crop Rice Harvesting

Harvesting main crop rice with a wide header at a required height can increase its ratoon crop yield by decreasing the stubble rolling rate. However, an increased harvest width brings in more input material in a specific time, causing the size enlargement or working speed slowdown of harvesters. To solve this issue, a double-cutterbar structure was proposed. To provide a design baseline for the structure, the cutterbar configuration methods based on rice plant deformation were developed and verified, stalk shearing tests were conducted, and a double-cutterbar prototype was fabricated and tested. The results indicated that the methods developed for the configuration of the upper and lower cutterbars could considerably implement their functions of lowering the straw-grain ratio and keeping stubble height as required. The shearing tests indicated that the bevel angle significantly influenced the total shearing energy on each cutting point in Internode 2 and 3 (p < 0.05) due to the increased stalk cross sectional area. The stubble rolling rate, panicle straw length and stubble height of the developed harvester were 26.9 %, 125 ± 80 mm and 332 ± 22 mm, respectively, which could meet the requirements of main crop rice harvesting. The outcomes indicated the functionality and practicability of the double-cutterbar structure developed based on rice plant deformation and shearing properties.

Effect of Modified Sludge on the Particles Flocculation and Slurry Stability in the Co-slurry of Sludge and Petroleum Coke

Sewage sludge modified by Ca(OH)2 and Fe2(SO4)3 were used as make the slurry with petroleum coke, and changes in the size distribution and a total number of particles in the slurry were determined by Focused Beam Reflectance Measurement (FBRM) to explore the particles flocculation mechanism. In addition, the structural strength of petroleum coke sludge slurry (PCSS) was calculated by two mathematic models to illustrate the how the sludge improves the stability of PCSS. The results indicated that the absolute value of the Zeta potential of PCSS increased with the sludge addition and that PCSS stability improved. However, the absolute value of the Zeta potential decreased and the stability declined after the sludge was modified by Fe2(SO4)3 and Ca(OH)2. Petroleum coke particles were wrapped by sludge flocs, and small particles flocculated during their co-slurry process to form a spatial network structure, effectively prevented the settlement of petroleum coke particles and ultimately improved the stability of slurry. The calculation results obtained by the two mathematic models reveal that the shearing energy consumption per-unit-quality of PCSS using raw sludge is twice or thrice than that of PCWS. However, energy consumption was reduced after the sludge was modified by Fe2(SO4)3.

One-dimensional models of fourth and sixth orders for rods derived from three-dimensional elasticity

The displacement field in rods can be approximated by using a Taylor–Young expansion in transverse dimension of the rod. These involve that the highest-order term of shear is of second order in the transverse dimension of the rod. Then we show that transverse shearing energy is removed by the fourth-order truncation of the potential energy and so we revisit the model presented by Pruchnicki. Then we consider the sixth-order truncation of the potential which includes transverse shearing and transverse normal stress energies. For these two models we show that the potential energies satisfy the stability condition of Legendre–Hadamard which is necessary for the existence of a minimizer and then we give the Euler–Lagrange equations and the natural boundary conditions associated with these potential energies. For the sake of simplicity we consider that the cross-section of the rod has double symmetry axes.

Lie Group Modeling of Nonlinear Helical Beam Elements

A viscoelastic beam model is presented based on SE(3) group theory. We discretize a rod with beams between finite frames on the rod and regard the configurations of these frames as elements of the SE(3) Lie group. Two subsequent frames are connected by a beam. The curvatures and strains are assumed to be constant on the trajectory between them. If the deflection curve of the beam is modeled as a helix, the resulting beam model is geometrical exact for large bending deformations. The stiffness matrices of the discrete beam elements result from the potential extensional and shearing energy as well as from the potential bending and torsion energy. The benefit of this SE(3) modeling for translational elastic coordinates and for translational forces in comparison to an SO(3) × ℝ3 variant is demonstrated.

Nb effects on the structural and mechanical properties of TiAl alloy: Density-functional theory study

Nb can improve the oxidation resistance of TiAl; however, the reported concomitant effects on the mechanical properties are controversial. Therefore, the effect of different Nb additions (0∼20.83 at.% Nb) on the lattice distortion as well as dislocation nucleation and mobility of TiAl were examined by density-functional theory calculations to solve the puzzle. The calculation of the formation energy and c/a ratio showed that Nb slightly decreases the phase stability and enhances the anisotropy. The variation of shearing energy barrier demonstrates an interesting staged strengthening effect of Nb on TiAl. Further analyses of the charge density difference and the partial density of states reveal that the physical origination is the electronic anisotropy, which is correlated with the Nb content and distribution.

Energy Requirements of Mechanical Shear Degradation in Concentrated Polymer Solutions

Molecular weight decrease by mechanical shearing results when solutions of around 10% of polyisobutene having average molecular weights above 500,000 are forced through a capillary at nominal rates of shear above 10,000 sec−1. Comparison of observed plots of shear load vs. duration of shearing at fixed rates of shear during this degradation process with the corresponding estimated plots which would be expected to obtain if degradation did not occur provide a means of evaluating the amount of applied shearing energy which is dissipated by the degradation process. The result is several hundred thousand kilo-calories per mole of broken bonds, which is several thousand times the bond energy of carbon-carbon bonds. This finding is consistent with the hypothesis that whenever a bond breaks the system loses much of the free energy temporarily stored in bonds and macromolecular chains located in a comparatively large volume surrounding the broken bond, these bonds and chains having been involved in concentrating the required activation energy into the ruptured bond.