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In this study, an experiment and a simulation were carried out on colliding an adhesively-bonded tapered double cantilever beam (TDCB) at the impact velocities of 5 m/s, 7.5 m/s and 12.5 m/s. The analysis method of the corrected beam theory (CBT) was used to obtain the rate of energy release in the bonded area according to the crack progression, and a simulation was performed to determine the maximum strain energy during the impact analysis as a means to examine the mechanical properties of aluminium alloy. The experimental data were found to be higher than the simulation data. This is deemed to explicable by the fact that the adhesive strength was maintained even after the specimen separated in the experiment. Crack progression occurred, irrespective of the impact velocity, and high strain energy occurred at the end of the bonded region, thereby causing the strain energy to increase in the final stages. Also, the maximum load applied on the pin and the maximum strain energy in the bonded area were shown increase at higher impact velocities. The results of the experiment and simulation performed in this study are expected to serve as important data in developing a safety design for composite materials that can help prevent the progression of cracks caused by impact. [ABSTRACT FROM AUTHOR]

Double-cantilever beam (DCB) and tapered double-cantilever beam (TDCB) specimens are the test configurations most commonly used to measure the fracture toughness of composites and adhesive joints. Strain rates of 1 to 18.47 m/s were applied to the test specimens via high-speed hydraulic test equipment. Because the fracture occurs through the adhesively bonded joints and the cracks grow rapidly, the crack length and beam displacement were recorded by a high-speed camera. An energy range from 0 to 10 J was often observed in the high-strain-rate fracture experiments for nonlinear plastic behavior of the dynamically loaded adhesively bonded DCB and TDCB specimens. The range of energy release rates (fracture energy) for TDCB specimen was 2 to 3 times higher than that of a DCB specimen for all high strain rates. The fracture energy of automotive adhesive joints can be estimated using the experimental results in this study for the fracture toughness (G) under high rates of loading. The crack grows as the applied fracture energy exceeds the value of the critical energy release rate (G) at the crack tip. The energy release rate was calculated using the fracture mechanics formula. The key fracture mechanics parameter, the fracture energy GIC, was ascertained as a function of the test rate and can be used to assess and model the overall joint performance. [ABSTRACT FROM AUTHOR]

An accurate understanding of the factors that influence farmers' adoption of a crop is critical for effective policy promotion and technical support. Agroforestry crop adoption is a complex topic involving many factors not often addressed by tradition crop adoption models. This complexity, when applied to Jatropha ( Jatropha curcas L.), an often widely promoted yet poorly understood biofuel feedstock crop, requires a detailed analysis across diverse topics. Such an analysis was carried out through applying rigorous statistical tools to the data acquired from an interview-based household survey among Malian farmers and was combined with relevant geospatial datasets. The results showed that though farmers' adoption is based on a wide variety of factors from household preferences, resource endowments, bio-physical factors, and market incentives, factors related to risk and uncertainty appear to provide the strongest correlation. Specifically, the number of visits that an agriculture extension agent makes with a farmer was found to be the most significant factor influencing adoption. [ABSTRACT FROM AUTHOR]

In this paper, a unidirectional carbon-fiber composite is both experimentally and numerically investigated to study the nonlinear material behavior of impacted double cantilever beam (DCB) specimens. For the impact analysis, the load and the displacement applied from pin onto end block as well as the crack energy release rate are measured and compared with the finite element analysis results. The energy release rate is a critical measure of the resistance to crack propagation, which can be estimated by the force and displacement at the crack tip. It is found that the energy release rate measured from impact tests on the specimens is well predicted by the finite element model suggested in this study. [ABSTRACT FROM AUTHOR]