PurposeThe purpose of this paper is to provide a summarization and review of the present author's main investigations on failure modes of reticular metal foams under different loadings in engineering applications.Design/methodology/approachWith the octahedral structure model proposed by the present authors themselves, the fundamentally mechanical relations have been systematically studied for reticular metal foams with open cells in their previous works. On this basis, such model theory is continually used to investigate the failure mode of this kind of porous materials under compression, bending, torsion and shearing, which are common loading forms in engineering applications.FindingsThe pore-strut of metal foams under different compressive loadings will fail in the tensile breaking mode when it is brittle. While it is ductile, it will tend to the shearing failure mode when the shearing strength is half or nearly half of the tensile strength for the corresponding dense material and to the tensile breaking mode when the shearing strength is higher than half of the tensile strength to a certain value. The failure modes of such porous materials under bending, torsional and shearing loads are also similarly related to their material species.Originality/valueThis paper presents a distinctive method to conveniently analyze and estimate the failure mode of metal foams under different loadings in engineering applications.
A mathematical model accounting for the pressure oscillation when flooding occurs is presented
to predict the velocity limit of an immiscible vapor mixture condensing in a vertical tube. This
model incorporated the parameters of vapor inlet velocity, pressure drop, interfacial friction
stress, tube inside diameter, and the fluid physical properties. The in-tube condensation
experiments of an oil−steam vapor mixture with various mass ratios have been conducted using
an 18 mm i.d. brass tube and a 20 mm i.d. glass tube, respectively. The model predicted that
data agreed very well with the experimental data, indicating that this model is valid to predict
the velocity limit of the immiscible vapor mixture condensing in a vertical tube.
Experiment was conducted to study steam condensation in horizontal microchannel etched on silicon wafer and bonded by a Pyrex glass plate from the top. The trapezoidal microchannel had a top width of 7943.11μm and depth of 81.77μm with hydraulic diameter of 161.49μm. The experiments were performed at different steam mass fluxes ranged from 128 kg m−2 s−1 to 320 kg m−2 s−1, while the inlet temperature of cooling water was fixed at 30°C or 50°C. Characteristics of condensation heat transfer and pressure drop in microchannels were measured and discussed. The temperature of Pyrex glass and local steam quality were also tested. It is found that the heat transfer flux, heat transfer coefficient and pressure drop depend greatly on steam mass flux and cooling water temperature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.