摘要:
Castor oil has been widely used in various fields due to its properties, leading to large attention for its extraction mechanism. To research the castor oil extraction mechanism during pressing, a self-developed uniaxial compression device combined with an in situ observation is established. The effects of pressure, loading speed, and creep time are investigated, and a finite element model coupling with multi-physics is established for castor oil pressing extraction, verified by the seed cake experimental compression strain matching with numerical simulation under the same condition. Simulation results indicated that the pressing oil extraction process can be divided into two stages, Darcy's speed shows the first sharp decreasing stage and the second gradual increasing stage during porosity and pressure interaction. In the first stage, porosity is dominant on Darcy's speed. With porosity decreasing, the pressure effect on Darcy's speed exceeds porosity in the second stage. With seed thickness increasing, Darcy's speed first increases and then decreases. With loading speed increasing, Darcy's speed increases. Darcy's speed decreases constantly with creep time increasing. This study can provide basic theoretical and practical guidance for oil extraction.
摘要:
Castor oil has attracted large attention for wide applications, including lubrication oil and bioenergy resources. Castor seeds mechanical pressing is widely used for oil extraction. To better research castor seeds mechanical-structural damage behavior and oil extraction mechanism during extrusion, a self-developed mechanical pressing test setup combined with in situ observation is built for oil output behavior. Influencing factors of working pressure, speed, temperature and creep time on oil outflow were investigated. The results indicate that seeds squeezing extraction can be divided into three stages, preloading, oil discharging, compressing consolidation stage, matching with pressing cake structural evolution. As working pressure increases, oil yield shows an upper parabola relation with pressure. When pressure exceeding 25 MPa, castor oil yield increasing tends to stabilize, reaching 38%. Speed effect showed down parabola relation on oil yield, opposite to stress factor. Creep time promoted oil output with upper parabola within 720 s. When temperature below 120 degrees C, a linear increasing relation on oil yield presents. Oil yield decreases when above 120 degrees C. This research provides in-depth theoretical guidance for industrial castor oil extraction.Practical ApplicationsCastor seeds are rich in oil content. Extracted castor oil has been widely used for industrial applications such as biodiesel, lubricants, medicine. Mechanical extraction working parameters optimization can improve oil yield of castor seeds. The research provides a basic working optimization for castor seeds oil extraction. Castor oil has unique properties and has been proved to be a high promising renewable and independent energy sources. Compared with solvent oil extraction, mechanical oil pressing extraction method has higher oil quality and safety. The mechanical extracted oil is pure without organic solvent. In the research, castor seeds compression-structural damage property and oil extraction mechanism were studied. Besides, the influence factors including compression pressure, speed, temperature and creep time are analyzed, working optimization for castor seeds oil extraction. The research provides important reference value for the mechanical pressing process and mechanical design of castor seeds in the practical applications. Using the self-developed mechanical pressing test setup and in situ observation technology, the castor seeds mechanical-structural damage behavior during the pressing process and oil extraction mechanism were analyzed, as well as the effects of pressure, speed, temperature, and creep time on the oil yield. image
关键词:
Ship collision;Raked bow;Ship side shell;Experiments;Numerical simulations;Damage characteristics
摘要:
Experimental and numerical simulation studies are conducted on a scaled ship side-shell quasi-statically punched at the mid-span by a raked bow indenter to investigate its damage characteristics from deformation to a large opening. A scaled stiffened panel and a raked bow indenter are designed in model tests. Numerical simulation is performed to simulate the indentation responses. The experimental and numerical results are compared well in terms of resistance-penetration curves, final damage shapes and especially the three failure models, i.e., initial fracture, model “I” crack and model “III” crack. In addition, the whole damage process, the energy dissipation characteristics of the specimen and failure related parameters in three specific failed elements corresponding to the three failure models are analyzed through numerical simulation. The results demonstrate that the energy dissipated by the stiffener and frictional effect is substantial during the crack propagation process. In addition, shell elements involved with three failure models prior to fracture are mainly subjected to tension and bending effects, as shell elements cannot satisfactorily simulate the transverse shear effect. Finally, the influences of collision parameters, the failure sequence of integration points, modeling of weld seams, mesh resolution and failure criteria on the numerical simulation results are discussed.
摘要:
<jats:p>Products from castor seeds have been widely used in various fields. In order to study the breaking behavior and rupture mechanism of castor seed episperm during coat shelling process, the force-structure property of coating castor seed was investigated by a self-developed texture analyzer with in situ optical microscopic observation. Influences of compression distance, velocity and working temperature were studied. The results showed that castor seed episperm rupture commonly happened from the tail end to the first end. Compression distance effect can change the episperm cracking degree. Under pressing distance 2–3 mm, the episperm easily cracked into two flaps, and the breaking force stabilized at 77 N. Pressing velocity has no significant effect on episperm breaking. Temperature changes the physical property. With an increase in temperature, breaking force presents a “slope” decline; under a temperature of 120 ℃, temperature effect on the breaking force decreased significantly and the breaking force fell to about 52 N. The research results can provide theoretical basis for the castor episperm peeling.</jats:p>