Research on Structural–Mechanical Properties during the Castor Episperm Breaking Process

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.

Energy Absorption and Limit Velocity of Epoxy Composites Incorporated with Fique Fabric as Ballistic Armor—A Brief Report

Polymer composites reinforced with natural fabric have recently been investigated as possible ballistic armor for personal protection against different levels of ammunition. In particular, fabric made of fique fibers, which is extracted from the leaves of the Furcraea andina, was applied as reinforcement for polymer composites used in a multilayered armor system (MAS). The superior performance of the fique fabric composites as a second MAS layer motivated this brief report on the determination of the absorbed energy and capability to limit velocity in the stand-alone ballistic tests. The single plates of epoxy composites, which were reinforced with up to 50 vol% of fique fabric, were ballistic tested as targets against 7.62 mm high-speed, ~840 m/s, impact ammunition for the first time. The results were statistically analyzed by the Weibull method and ANOVA. The absorbed energies of the 200–219 J and limit velocities of 202–211 m/s were found statistically similar to the epoxy composites reinforced with the fique fabric from 15 to 50 vol%. Predominantly, these findings are better than those reported for the plain epoxy and aramid fabric (KevlarTM) used as stand-alone plates with the same thickness. Macrocracks in the 15 and 30 vol% fique fabric composites compromise their application as armor plates. The delamination rupture mechanism was revealed by scanning electron microscopy. By contrast, the integrity was maintained in the 40 and 50 vol% composites, ensuring superior ballistic protection compared to the use of KevlarTM.

Electrohydrodynamic Instabilities in Free Emulsion Films

Electrohydrodynamic instabilities were induced in thin water-in-oil emulsion films by application of external DC electric field. The dominant wavelengths of instabilities were measured for constant electric fields of various strengths. The dominant wavelengths agreed reasonably well with theoretical predictions based on a linear stability model. The linear stability model used in this study took into account experimentally measured repulsive disjoining pressure and calculated Maxwell stress. The observation of such instabilities can help to understand the rupture mechanism of emulsion films under the influence of electric field.

21 May 2003 Boumerdès Earthquake: Numerical Investigations of the Rupture Mechanism Effects on the Induced Tsunami and Its Impact in Harbors

In order to obtain a fair and reliable description of the wave amplitude and currents in harbors due to the tsunami generated by the 21 May 2003 Boumerdès earthquake (Algeria), a numerical investigation has been performed with a standard hydraulic numerical model combined with various source fault models. Seven different rupture models proposed in literature to represent high frequency seismic effects have been used to simulate tsunami generation. The tsunami wave propagation across the Western Mediterranean Sea and in bays and harbors of the Balearic Islands is simulated, and results are checked against sea level measurements. All of them resulted in a significant underestimation of the tsunami impact on the Balearic coasts. In the paper the best fitting source model is identified, justifying the energy intensification of the event to account for low frequency character of tsunami waves. A fair correspondence is pointed out between damages to boats and harbor infrastructures, reported in newspapers, and wave intensity, characterized by level extremes and current intensity. Current speed and amplitude thresholds for possible damage in harbors suggested respectively by Lynett et al., doi.org/10.1002/2013GL058680, and Muhari et al., doi.org/10.1007/s11069-015-1772-0, are confirmed by the present analysis.