Investigation of the process of peeling walnuts between two parallel plates

The article provides a detailed overview of the process of splitting the kernel of a walnut. Examples of many ways to split the shell are given, all of their disadvantages and advantages are listed. The mechanical method of peeling nuts using low-frequency oscillations has been theoretically investigated and substantiated. The kinematics of the process of crushing nuts between two parallel plates has been extensively analyzed. Graphical correlations were obtained between the size of the nut shell and the dynamics of the driving force of the nut moisture. It is revealed that the process of destruction of the shell of a walnut consists of four stages, corresponding to the laws of brittle destruction. Presents: - dependence of the maximum force of crushing of a shell of a nut at 5% humidity; - the dependence of the maximum crushing force of nuts at different shell thickness for the case of horizontal positioning of the nut between two plates with perpendicular force on the surface of the joint halves of the nut; - the dependence of the maximum crushing force according to the humidity of the nuts at different shell thicknesses for the case of vertical positioning of the nut between two parallel plates with a vertical driving force; - the dependence of the maximum crushing force with the moisture of the nuts at different shell thicknesses for the case of horizontal positioning of the nut between two parallel plates with a force action along the slit. The energy of splitting (crushing) of nuts at their location in different positions between two parallel plates is also determined. Where it has been proved that the energy consumed in the process of crushing increases with the thickness of the shell of a walnut. At the same time, it is proved that energy consumption depends on the location of the nut in the process of crushing. Graph analyzes were performed to show that maximum crushing energy is recorded in the case of a horizontal arrangement of a nut with a perpendicular crack action. In this study, a large amount of information was obtained regarding the splitting of the walnut, depending on the structural and mechanical characteristics of the products, which in the process of processing are important for the determination of certain rational technological parameters.

Influence of tire-cord layers and arrangement direction on the physical properties of polyester tire cord reinforced with chloroprene rubber composite materials

Polyester tire cord is used as reinforcement for making chloroprene rubber (CR) composite materials. This study investigated the influences of polyester tire-cord layers and arrangement direction on the mechanical properties of CR composite materials. The experimental results indicate that the optimal temperature and heating time for CR vulcanization are 170°C and 35 min, respectively. This processing condition enabled CR to achieve rapid vulcanization and exhibit optimal mechanical properties. The hardness and compression stiffness of the CR composites increased with increasing tire-cord layers. This phenomenon reduced the occurrence of creep under long-term loading but increased the compression set. In addition, when the arrangement direction of the tire cord and the stretching direction of CR were perpendicular, crack formation and growth easily developed, which reduced the bending-fatigue resistance of CR.

THE INVESTIGATION OF THE ELASTIC-PLASTIC BEHAVIOR USING THE PROPERTY GRADIENT OF THE INTERFACIAL REGION IN FIBER REINFORCED MMC

In this study, the interfacial perpendicular crack behavior and stress state of the unidirectional fiber reinforced Metal Matrix Composites (MMCs) are investigated by using FEA under the transverse loading. The fiber assumed as isotropic linear elastic SiC and the matrix is assumed as isotropic elastic-plastic Ti . The fiber/matrix interface is modeled as multi thin layer with different linear material properties. The behavior of perpendicular crack to the interface according to the change of the interface characteristics and thickness are evaluated.

Fitness-for-Service Assessment for a Radioactive Waste Tank That Contains Stress Corrosion Cracks

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The tanks are examined by ultrasonic (UT) methods for thinning, pitting, and stress corrosion cracking in order to assess fitness-for-service. During an inspection in 2002, ten cracks were identified on one of the tanks. Given the location of the cracks (i.e., adjacent to welds, weld attachments, and weld repairs), fabrication details (e.g., this tank was not stress-relieved), and the service history the degradation mechanism was stress corrosion cracking. Crack instability calculations utilizing API-579 guidance were performed to show that the combination of expected future service condition hydrostatic and tensile weld residual stresses do not drive any of the identified cracks to instability. The cracks were re-inspected in 2007 to determine if crack growth had occurred. During this re-examination, one indication that was initially reported as a “possible perpendicular crack <25% through wall” in 2002, was clearly shown not to be a crack. Additionally, examination of a new area immediately adjacent to other cracks along a vertical weld revealed three new cracks. It is not known when these new cracks formed as they could very well have been present in 2002 as well. Therefore, a total of twelve cracks were evaluated during the re-examination. Comparison of the crack lengths measured in 2002 and 2007 revealed that crack growth had occurred in four of the nine previously measured cracks. The crack length extension ranged from 0.25 to 1.8 inches. However, in all cases the cracks still remained within the tensile weld residual stress zone (i.e., within two to three inches of the weld). The impact of the cracks that grew on the future service of Tank 15 was reassessed. API-579 crack instability calculations were again performed based on expected future service conditions and trended crack growth rates for the future tank service cycle. The analysis showed that the combined hydrostatic and tensile weld residual stresses do not drive the identified cracks to instability. This tank expected to be decommissioned in the near future. However, if these plans are delayed, it was recommended that a third examination of selected cracks in the tank be performed in 2014.

Estimation of the Elastic-Plastic Fracture Behavior of Fiber Reinforced MMC According to the Change of Interfacial Characteristics

Fiber reinforced metal matrix composites (MMCs) are recently used in automobile, ship, aerospace and manufacturing industry because they have high stiffness and strength. The effective utilization of the strength and stiffness of the fiber reinforced MMCs depends on efficient load transfers from the matrix to fibers through the interfacial region. However, during the fabrication and afterward utilization of composites, so many numbers of micro crack may extend, especially at the interface, even before any load has been applied. Thus, in this study, the interfacial stress state and behavior of the interfacial perpendicular crack for transversely loaded unidirectional fiber reinforced MMCs investigated by using the elastic-plastic finite element analysis.