阅读说明：本技术 一种制备非冻结模型冰的人工引晶模具 (Artificial seeding die for preparing non-frozen model ice ) 是由 黄焱 王定仕 田育丰 于 2019-10-10 设计创作，主要内容包括：本发明涉及一种制备非冻结模型冰的人工引晶模具,包括模具外板、制模室和玻璃纤维丝,制模室由模具外板即上盖板、侧板和底板围成,模具上盖板为多孔板,玻璃纤维丝穿过各个孔形成阵列,玻璃纤维丝的直径和间距根据拟制备模型冰力学参数进行设置。(The invention relates to an artificial seeding die for preparing non-frozen model ice, which comprises a die outer plate, a die making chamber and glass fiber yarns, wherein the die making chamber is surrounded by the die outer plate, namely an upper cover plate, a side plate and a bottom plate, the upper cover plate of the die is a porous plate, the glass fiber yarns penetrate through each hole to form an array, and the diameter and the distance of the glass fiber yarns are set according to the mechanical parameters of the model ice to be prepared.)

1. The artificial seeding mold for preparing the non-frozen model ice comprises a mold outer plate, a mold making chamber and glass fiber yarns, wherein the mold making chamber is surrounded by the mold outer plate, namely an upper cover plate, side plates and a bottom plate, the mold upper cover plate is a porous plate, the glass fiber yarns penetrate through the holes to form an array, and the diameters and the intervals of the glass fiber yarns are set according to mechanical parameters of the model ice to be prepared.

Technical Field

The invention belongs to the technical field of engineering in alpine regions, and relates to a method for generating and preparing non-frozen model ice for simulating sea ice in the alpine regions.

Background

The ice mechanics and ice engineering model tests have the characteristics of both fluid model tests and material model tests. The material model test requires that the physical and mechanical properties of the model material and the prototype material meet the requirement of a model scale, so that the failure mode of the model material and the expressed mechanical properties are similar and reducible. In the ice mechanical model test, the physical and mechanical properties of the prepared model ice and the natural sea ice are required to be similar.

Sea ice is a material with very complex mechanical properties, and the crystal structure characteristics of the sea ice are determined by the crystal growth process of the sea ice. When the temperature of the seawater is reduced to below zero, firstly, impurity particles or snowfall small ice crystals in the water are taken as crystallization nuclei, and the crystallization gradually grows around the crystallization nuclei to form small ice needles. And as the volume of the small ice needle is increased, the buoyancy is increased, and the small ice needle gradually floats to the position near the water surface. The open sea surface can cause severe water body disturbance due to waves, ocean currents, wind and the like, under the environment condition, the growth direction of ice crystals is random, the ice crystals gradually grow and are connected, and finally, granular ice layers which are randomly distributed in the directions of an ice crystal base plane and a C axis (an axis vertical to the ice crystal base plane) are formed. Under the temperature gradient formed by the cold air on the water surface and the warmer water under the granular layer, the ice crystals grow rapidly along the direction of the temperature gradient to form a columnar texture structure. In the horizontal direction, under the influence of no fixed direction ocean current, the ice crystals are randomly distributed in the C-axis direction, so that a columnar ice layer is formed. Compared with the granular ice layer on the surface, the columnar ice layer has higher growth speed and is the main component of the sea ice. In the freezing process of the sea ice, defect structures such as bubbles, brine, cracks and the like are always mixed in the sea ice. The bond strength within the ice crystals is much greater than the bond strength between crystals, and therefore these defect structures are often distributed in regions between the ice crystals, thereby forming a distribution characteristic along the columnar grain.

At present, model ice materials used in model tests in the international ice mechanics and ice engineering community are mainly divided into low-temperature frozen model ice and non-frozen model ice. The low-temperature freezing model ice is the main model ice type used by various low-temperature towing ice pool laboratories. The formation process of the natural sea ice is simulated in a laboratory by different technical means in each ice water tank, so that the low-temperature frozen model ice with a crystal structure similar to that of the natural sea ice is prepared, and the macroscopic mechanical property of the model ice is ensured to be similar to that of the natural sea ice. Compared with the low-temperature freezing model ice, the mechanical property of the non-freezing model ice is insensitive to the environmental temperature, and the non-freezing model ice can be applied to wider test scenes. Meanwhile, the non-frozen model ice also has the advantages of short preparation period, low manufacturing cost, batch production and the like.

Since the last 70 s, a series of non-freezing model ice preparation technologies were developed abroad. In 1971, Hovacraft, UK, used paraffin as a base material, and a mixture solution was prepared by melting by heating and then solidified by cooling to obtain a non-frozen model ice. In 1975, Tryde takes plaster of paris, plastic fine particles, salt, borax and water as main raw materials, heats the raw materials to form a mixture solution, and cools the mixture solution to prepare the non-freezing model ice with the density similar to that of natural sea ice. In 1978, Michel, a canadian scholar, used a mixture of paraffin wax and oil as the main ingredients, and produced non-frozen model ice having properties similar to those of Tryde model ice by a process of heating, dissolving, and then cooling and solidifying. In 1984, Schultz and Free used a procedure similar to that of Hovacraft, england, and a mixture solution of polyethylene powder, polyethylene pellets, heavy vegetable oil, light vegetable oil and stearic acid obtained after heating was poured onto water and cooled to solidify, to prepare a MOD unfrozen model ice. In 1990, Beltao et al heated PVC resin, cement, plaster of Paris, glass beads and water to prepare a solution, and cooled and solidified to obtain a SYG non-frozen model ice. In China, at the end of the last 90 s, research and development of a non-freezing model ice preparation technology are started. In 2001, Li Shi Jun et al, university of Process engineering, mixed polypropylene particles, white cement and water, stirred, molded and cured to make DUT-1 non-frozen model ice. In 2017, luwanzhen and the like of Harbin engineering university heat paraffin and polystyrene foam to form a mixture solution, and after cooling, non-frozen model ice is obtained and used for a propeller ice cutting test.

According to the process flow of the existing non-freezing model ice preparation technology, the existing preparation methods do not interfere with the crystallization process of the model ice crystals, and the environmental conditions of the crystallization process of the model ice crystals are greatly different from those of natural sea ice. Therefore, the model ice obtained in such an environment does not have a columnar texture structure similar to that of natural sea ice, and thus the model ice may exhibit a failure mode and crack propagation characteristics different from those of natural sea ice. There is a need to improve the existing non-freezing model ice preparation technology, and to control the crystallization process of the model ice crystals by artificial seeding technology, so as to induce the nucleation and growth directions of the model ice crystals, thereby obtaining the columnar texture characteristics similar to those of natural sea ice.

The existing non-freezing model ice preparation method mainly has the technical problem that the growth mode of a model ice crystal is obviously different from the crystallization process of natural sea ice. The crystallization process of natural sea ice is influenced by environmental conditions such as sea surface disturbance, sea water temperature gradient and the like, and finally a layered structure consisting of a surface granular ice layer and a lower cylindrical ice layer is formed. Under the influence of the temperature gradient of the seawater, the natural sea ice can form a columnar texture structure characteristic, and the internal defect structure of the natural sea ice is also in a columnar distribution form along the crystal boundary. The existing non-freezing model ice preparation method does not intervene in the crystallization process, and model ice crystals naturally crystallize and grow in a uniform and stable environment, so that a uniform crystal structure form is obtained. The difference of the crystallization process needs to induce the crystal growth mode of the paraffin base material to approach the crystallization process of the natural sea ice by seeding and controlling the nucleation and growth of the model ice through a manual control anisotropic nucleation field method.

Disclosure of Invention

The invention aims to overcome the defects of the existing non-freezing model ice preparation technology and provide an artificial seeding mold for preparing non-freezing model ice. The mould of the invention can improve the crystallization mode in the existing non-freezing model ice preparation process, intervene the nucleation process and the growth mode of the model ice crystal, and prepare the non-freezing model ice with similar columnar texture structure with the natural sea ice by the artificial seeding technology and the crystal control technology. Meanwhile, the artificial seeding die can also promote the defect structure in the model ice to form the characteristic distributed along the columnar texture, so that the crack propagation mode and the fracture characteristic of the model ice have better similarity with the natural sea ice. The non-frozen model ice prepared by the mould of the invention achieves a good simulation level of natural sea ice in a failure mode. The technical scheme is as follows:

the artificial seeding mold for preparing the non-frozen model ice comprises a mold outer plate, a mold making chamber and glass fiber yarns, wherein the mold making chamber is surrounded by the mold outer plate, namely an upper cover plate, side plates and a bottom plate, the mold upper cover plate is a porous plate, the glass fiber yarns penetrate through the holes to form an array, and the diameters and the intervals of the glass fiber yarns are set according to mechanical parameters of the model ice to be prepared.

The non-freezing model ice prepared by the mold based on the artificial seeding method has mechanical properties similar to those of natural sea ice, has similar crack propagation characteristics and failure modes, can effectively improve the accuracy of the non-freezing ice mechanical model test, shortens the test period and reduces the test cost. The concrete advantages are as follows: and (3) artificially seeding by using glass fiber, and intervening the crystallization process of the liquid paraffin mixed solution to promote the prepared model ice to form a columnar texture structure similar to natural sea ice. Meanwhile, the glass fiber left in the model ice can effectively simulate the defect structure and the distribution form thereof in the natural sea ice. The non-frozen model ice obtained by the artificial seeding preparation technology has better similarity with natural sea ice, so that the crack propagation and failure modes of the model ice are closer to those of the natural sea ice.

Drawings

FIG. 1 is a schematic structural diagram of a mold for preparing non-frozen model ice based on an artificial seeding method.

Fig. 2 is a schematic view of the structure of the upper cover plate of the mold.

FIG. 3 shows the failure of the uniaxial compression test. (a) Is the failure condition of the uniaxial compression test carried out on the improved low-temperature frozen urea model ice. (b) The damage condition of the single-axis compression test of the non-frozen model ice based on the artificial seeding method is shown in the invention.

The reference numbers in the figures illustrate: 1. a mold making chamber; 2. an upper cover plate of the mold; 3. opening a hole in an upper cover plate of the mold; 4. glass fiber yarn.

Detailed Description

The present invention will be described in detail with reference to examples.

1. Preparing a paraffin wax mixed solution. In order to effectively simulate the density of natural sea ice, paraffin with the density similar to that of the sea ice is selected as a base material. The solid paraffin was heated until it was completely melted into liquid paraffin. In order to improve the brittleness of the non-frozen model ice and make the non-frozen model ice more similar to natural sea ice in mechanical property, 1 percent of gypsum powder, 3 percent of quartz powder and 1.5 percent of silicon powder are added into liquid paraffin and stirred evenly for standby.

2. Assembling the non-freezing model ice preparation mould. And the prefabricated ABS plates are spliced according to the pattern shown in figure 1, the side plates and the bottom plate of the non-freezing model ice preparation mold are assembled, the outer parts of the plates are fixed by using adhesive tapes, and the mold is convenient to disassemble when the model ice is taken out. The mould 1 is a mould making chamber, and the liquid paraffin solution completes the crystallization and consolidation process in the mould making chamber to form the model ice.

3. The upper cover glass fiber was frozen. And (3) enabling the glass fiber yarns 4 to penetrate through the openings 3 of the upper cover plate to form a glass fiber array, wherein the glass fiber yarns are converged and connected together on the upper surface of the upper cover plate 2. The glass fiber yarns positioned below the upper cover plate 2 are parallel to each other and vertical to the upper cover plate, the length of the glass fiber yarns exposed below is the same as the thickness of a columnar crystal layer of the model ice to be prepared, and the distance between the lower end of the glass fiber and the bottom plate of the mold is equal to the thickness of the granular crystal layer of the model ice. The glass fiber diameters and the distances from each other are important factors affecting the mechanical properties of the model ice to be produced, and are set according to the target strength of the model ice to be produced, as shown in table 1. The aperture of the upper cover plate opening 3 is slightly larger than the diameter of the glass fiber so as to ensure that the glass fiber can smoothly pass through the opening. And (3) putting the assembled upper cover plate 2 with the glass fiber array into a freezer to ensure that each glass fiber yarn naturally droops, setting the temperature in the freezer to be-20 ℃, and cooling the temperature of the glass fibers to the temperature for later use.

TABLE 1 uniaxial compression strength of model ice at different glass fiber diameters and spacings

4. Pouring the paraffin wax mixed solution. The paraffin wax mixed solution which is stirred uniformly is slowly poured into the mould making chamber 1 until the mould making chamber is full.

5. And intervening the crystallization and consolidation process of the paraffin mixed solution by manual seeding and crystal control technologies. The cover plate 2 with the glass fiber array was removed from the freezer and slowly covered on the upper surface of the mold. The low-temperature glass fiber is inserted into the liquid paraffin mixed solution, and the solution is rapidly crystallized and solidified on the surface of the glass fiber.

6. Cooling and solidifying, and dismantling the die. The paraffin wax mixed solution is rapidly crystallized on the surface of the low-temperature glass fiber and grows along the vertical direction to form a columnar texture structure. And standing the mold, and waiting for gradual cooling and solidification of the paraffin mixed solution in a room temperature environment. And after the glass fiber is completely solidified, the mould is dismantled, and the upper cover plate 2 is taken down after the glass fiber on the upper surface is cut off. And forming a smooth plane on the contact surfaces of the model ice, the bottom plate of the mold and the side plates under the action of gravity, arranging and polishing the contact surfaces of the model ice and the upper cover plate to the plane by using a plane, turning the model ice up and down, and enabling the contact surfaces of the model ice and the bottom plate of the mold to be upward, thus obtaining the non-frozen model ice based on the artificial seeding method.

7. The uniaxial compression test examines the ice mechanical properties of the non-frozen model. The prepared non-frozen model ice was subjected to uniaxial compression test, as shown in fig. 3(b), and it was found that the non-frozen model ice had a failure form under uniaxial compression condition very similar to that of the low-temperature frozen model ice (as shown in fig. 3 (a)). By using the preparation method, the ice thickness range of the non-frozen model ice can be 3-5 cm, and the uniaxial compression strength range is 300-450 kPa.