Experimental Investigations of the Strengthening Effects of CFRP for Thin-Walled Storage Tanks under Dynamic Loads

In this study, the strengthening effects of different lamination conditions on carbon fiber reinforced polymers (CFRPs) for thin-walled storage tanks (TSTs) subjected to internal pressure under dynamic loads were experimentally investigated. A total of three small-scale models of TSTs were used for the investigation, including non-strengthened specimens, specimens strengthened with 0° CFRP layers, and specimens strengthened with 0°/90° CFRP layers. There were two types of tests for every specimen: the static and dynamic tests. A new experimental method using small steel balls was applied to create internal pressure in the TSTs. The results show that small steel balls could be used to increase the internal pressure compared to a normal liquid. Furthermore, the similarity rules for small-scale TSTs with small steel balls inside were also studied to consider the applicability of the models. The experimental results indicated that the CFRP layer could effectively restrain both static and dynamic hoop strains in the TSTs. Moreover, the CFRP layer could also remarkably reduce the impact of sloshing on the TST shells. The 0° CFRP layer proved to have better effects than the 0°/90° CFRP layers on the strengthening of the TSTs against dynamic loads.

Dynamic and High Temperature Quasi-static Examination of Tempered Glass

In everyday use glass materials cause a lot of damage or injuries when broken, as fracture mechanism and damage runoff cannot be predicted precisely. To gain knowledge on this issue, we studied the properties of tempered glass. The glass test samples were exposed to two types of destructive evaluations: normal and high temperature three-point bending and room temperature dynamic experiments with colliding small steel spheres. The evaluation showed that high temperature experiments are in correlation with sharp fracture edges, and dynamic impact creates shell featured circular crack propagation which prevents the spreading of the radial cracks, so the damage is concentrated to a small area.

Probing the Force Field to Identify Potential Energy

A small ball resting on a curve in a gravitational field offers a simple and compelling example of potential energy. The force required to move the ball, or to maintain it in a given position on a slope, is the negative of the vector gradient of the potential field: the steeper the curve, the greater the force required to push the ball up the hill (or keep it from rolling down). We thus observe the turning points (horizontal tangency) of the potential energy shape as positions of equilibrium (in which case the “restoring force” drops to zero). In this paper, we appeal directly to this type of system using both one- and two-dimensional shapes: curves and surfaces. The shapes are produced to a desired mathematical form generally using additive manufacturing, and we use a combination of load cells to measure the forces acting on a small steel ball-bearing subject to gravity. The measured forces, as a function of location, are then subject to integration to recover the potential energy function. The utility of this approach, in addition to pedagogical clarity, concerns extension and applications to more complex systems in which the potential energy would not be typically known a priori, for example, in nonlinear structural mechanics in which the potential energy changes under the influence of a control parameter, but there is the possibility of force probing the configuration space. A brief example of applying this approach to a simple elastic structure is presented.

Development of a Rapid Manufacturing Process for Concave and Convex Lens Arrays

This paper reports a rapid manufacturing process for the production of concave and convex lens arrays on the polymer substrate. In this method, many small steel balls with highly polished surfaces were placed in a rectangular cavity to form a closely packed small steel ball array. Then, a polymer substrate (PMMA sheet) was placed on top of the small steel ball array, and the stack of the PMMA sheet and the small steel ball array was placed in a hot embossing machine. During the hot embossing process operation, a concave lens array pattern is directly fabricated onto a polymer substrate. In addition, the diameter and depth of the concave lens array can be changed and controlled by adjusting the processing conditions of the hot embossing process. Thus, concave lens arrays with different dimension can be fabricated. Next, the polymer substrate with concave lens array pattern can be used as a mold for rapid replication of polymer convex lens array using vacuum-assisted UV molding process. In this way, various concave and convex lens arrays can be rapid fabricated with high throughput and low cost.

Study on Control Strategy of Hydrogen Risk in Small Containment Under Severe Accident

Hydrogen combustion or detonation happened in the containment within the process of the small reactor severe accident may threaten the integrity of the containment. In this paper, based on systemic design of the Small Modular Reactor (SMR) surrounded by the steel containment, an innovatory combustible gas control strategy which using the passive containment cooling system (PCCS) and passive autocatalytic recombiners (PARs) is made to control the hydrogen risk in the small steel containment. A severe accident hydrogen risk analysis model is built by the integrative severe accident analysis program MELCOR, the validity of the strategy is analyzed at a typical severe accident. With this understanding, a three-dimensional computed fluid dynamics hydrogen behavior analysis model of the small steel containment is established by GASFLOW code, and the gas distribution non-uniformity in the containment is analyzed. The result shows that the steam condensation process in the containment could be slowed down by controlling the action of PCCS, and the steam concentration in the containment could be in the range of high level, while the oxygen concentration could be in the range of low level. If the PARs were added, the PARs could consume the hydrogen and oxygen in the containment sustainedly. The containment atmosphere could be in an inerted condition during the accident process, even though the hydrogen concentration in the containment is high. The gas distribution non-uniformity analysis result shows that oxygen concentration was low in the extent of high hydrogen concentration and high steam concentration, the steam, oxygen and hydrogen distribution non-uniformity would not affect the inerted atmosphere of containment.