Artificial immune system for optimal design of composite hydrogen storage vessel

Based on the clonal selection principle in the biological immunology, an artificial immune system (AIS) is proposed to optimize the weight of Al-carbon fiber/epoxy composite hydrogen storage vessels under burst pressure constraint. The AIS simulates the generation of the antigens, the combination of the antigens and antibodies, and the selection, cloning and hypermutation of B cells, the maintenance of diverse antibody cells, the generation of the memory cells with high affinities and the death of the antibody cells with low affinities. Effects of the antibody size and the iterative number on the optimization results are explored. By comparison, the AIS shows higher search velocity and precision than the genetic algorithm and simulated annealing.     

Strain growth of the in-plane response in an elastic cylindrical shell

Strain growth is a phenomenon observed in containment vessels subjected to internal blast loading. The local elastic response of the vessel may become larger in a later stage compared to its response in the initial stage. To find out the possible mechanisms of the strain growth phenomenon, the in-plane response of an elastic cylindrical shell subjected to an internal blast loading is investigated. Vibration frequencies of membrane modes and bending modes are calculated theoretically and numerically. The dynamic non-linear in-plane responses of an elastic cylindrical shell subjected to internal impulsive loading are studied by theoretical analysis and finite-element simulation using LS-DYNA. It is shown that the coupling between the membrane breathing mode and flexural bending modes is the primary cause of strain growth in this problem. The first peak strain of the breathing mode and the ratio of the thickness to the radius are the dominant factors determining the occurrence of strain growth. Other mechanisms, which have been suggested in previous studies (e.g. beating between vibration modes with close frequencies, interactions between multiple vibration modes, resonance between vessel vibration and reflected blast wave, influence of structural perturbations), are secondary causes for the occurrence of the strain growth phenomenon in the studied problem.     

Effect of residual hydrogen content on the tensile properties and crack propagation behavior of a type 316 stainless steel

The tensile properties and crack propagation rate in a type 316 austenitic stainless steel prepared by vacuum induction melting method with different residual hydrogen contents (1.1–11.5 × 10⁻⁶) were systematically investigated in this research work. The room temperature tensile properties were measured under both regular tensile (12 mm/min) and slow tensile (0.01 mm/min) conditions, and the fracture properties of the tensile fractures with both rates were analyzed. It shows that the hydrogen induced plasticity loss of stainless steel strongly depends on the tensile rate. Under regular tensile condition, there is no plastic loss even when the hydrogen content is up to 11.5 × 10⁻⁶ while in the slow tensile condition, the plastic loss can be clearly identified rising with the increasing H contents. The fatigue crack propagation rate was tested at room temperature, and the crack growth rate formula (Paris) of the 316 stainless steels with varied H contents were obtained. The fatigue crack propagation rate test shows that the crack growth rate of the 316 stainless steel with 8.0–11.5 × 10⁻⁶ hydrogen is significantly higher than that of benchmark steel.     

Effect of pre-strain on hydrogen embrittlement of metastable austenitic stainless steel under different hydrogen conditions

The effects of internal hydrogen and environmental hydrogen on the hydrogen embrittlement of 304 austenitic stainless steels (ASSs) with varying degrees of pre-strain were investigated by a tensile test under cathodic hydrogen-charged, gaseous hydrogen and hydrogen-charged and gaseous hydrogen combined conditions. The internal hydrogen embrittlement of the 304 ASSs increased with increasing pre-strain, while the hydrogen embrittlement caused by the environment hydrogen increased and then decreased with increasing pre-strain. The hydrogen embrittlement mechanisms caused by the internal hydrogen or environmental hydrogen were different. The cracks caused by internal hydrogen or environmental hydrogen are mainly initiated in grain interior or at grain boundary, respectively. Under the coupling condition of internal hydrogen and environmental hydrogen, the hydrogen embrittlement of 304 ASSs was the strongest and increased with increasing pre-strain. Environmental hydrogen was dominant for low levels of pre-deformed specimens. Internal hydrogen was dominant for high levels of pre-deformed specimen.     

Finite Element Analysis of Delamination Behaviors of Composite Laminates under Hygrothermal Environment Using Virtual Crack Closure Technique

Journal of Failure Analysis and Prevention - This research aims to study the delamination behaviors of T700/8911 composite laminates under hygrothermal environment. For two mixed-mode I/II...     

超高压容器和管道周向超声检测(二)

超高压容器和管道作为高风险设备应用于石化、水晶制造等行业中。超高压容器和管道的内外径之比通常小于0．6，很难用常规的横波技术对其进行周向超声检测。本文分析了周向超声检测的主要技术难点，从厚壁筒形件的声场结构、径向缺陷的回波特征、表面缺陷的灵敏度、缺陷定位、灵敏度调节等方面进行试验和研究，总结出厚壁筒形件周向超声检测的工艺方法和参数，并在超高压人造水晶釜和超高压聚乙烯输送管的现场检测中对工艺方法和参数进行了验证，证明其对径向缺陷有足够的灵敏度和可靠性。     

Development of short chain fatty acid-based artificial neuron network tools applied to biohydrogen production

The biological production of biohydrogen through dark fermentation is a very complex system where the use of an artificial neuron network (ANN) for prediction, controlling and monitoring has a great potential. In this study three ANN models based on volatile fatty acids (VFA) production and speciation were evaluated for their capacity to predict (i) accumulated H₂ production, (ii) hydrogen production rate and (iii) H₂ yield. Lab-scale biohydrogen and VFA production kinetics from a previous study were used for training and validation of the models. The input parameters studied were: time and acetate and butyrate concentrations (model 1), time and lactate, acetate, propionate and butyrate concentrations (model 2), time and the sum of all VFA (model 3) and time and butyrate/acetate (model 4). All models could predict biohydrogen accumulated production, hydrogen production rate and H₂ yield with high accuracy (R² > 0.987). VFA_T is the input parameter indicated for processes using pure cultures, while for complex/mixed cultures a model based on acetate and butyrate is recommended.