A drop ball test fixture includes a bracket, first stoppers and connecting components. The bracket has bearing surfaces for bearing edges of a panel and to position the panel in a direction parallel to the bearing surfaces. At least part of each of the first stoppers is located above corresponding one of the bearing surfaces. Each connecting component includes a guide rod, a guide groove and a second stopper. The guide groove is formed on corresponding one of the first stoppers. One end of each of the guide rod is connected to the bracket while the other end thereof passes through the guide groove. Connecting structures are provided at different heights of the guide rod, and the second stopper is matched with and connected to corresponding one of the connecting structures at different heights above the guide groove so as to stop the upward movement of the first stopper.

An apparatus and a method for testing drilling efficiency of a drill bit, according to the present invention, calculate an amount of fractured rock according to a button arrangement, thereby obtaining an optimum button arrangement.

A ball drop iris is provided for use in a ball drop testing apparatus. Included on the iris is a lower housing having an upper mounting flange having a ball opening and a body depending from the flange, the body defining a passage through which a test ball passes. A control ring is disposed on the upper mounting surface for sliding, rotating action relative to the lower housing. A plurality of iris petals is provided, each operationally connected to the control ring and to the upper mounting flange to pivot between a closed position in which the ball opening is blocked, and an open position in which the petals are simultaneously retracted and the opening is clear for passage of a test ball.

A ball drop iris is provided for use in a ball drop testing apparatus. Included on the iris is a lower housing having an upper mounting flange having a ball opening and a body depending from the flange, the body defining a passage through which a test ball passes. A control ring is disposed on the upper mounting surface for sliding, rotating action relative to the lower housing. A plurality of iris petals is provided, each operationally connected to the control ring and to the upper mounting flange to pivot between a closed position in which the ball opening is blocked, and an open position in which the petals are simultaneously retracted and the opening is clear for passage of a test ball.

Hydrogels are networks of polymer chains that are swollen in water. These gels can protect vulnerable objects (e.g., an egg or a fruit) if wrapped there around. Gels are constructed by either physical cross-linking (e.g., gelatin) or chemical cross-linking (e.g., acrylamide). The addition of starch granules to the above gels greatly enhances their protective abilities. When a load strikes a gelatin gel containing 20% starch, the peak impact force is reduced by 25% when compared to a bare gel without the starch. Correspondingly, the coefficient of restitution (COR) is also lowered by the presence of starch (e.g., a ball bounces less on a starch-bearing gel). The impact-absorbing effects of starch granules are correlated to their ability to shear-thicken water. When starch granules are gelatinized by heat, they no longer give rise to shear-thickening, and in turn, their protective ability in a gel is also eliminated.

Hydrogels are networks of polymer chains that are swollen in water. These gels can protect vulnerable objects (e.g., an egg or a fruit) if wrapped there around. Gels are constructed by either physical cross-linking (e.g., gelatin) or chemical cross-linking (e.g., acrylamide). The addition of starch granules to the above gels greatly enhances their protective abilities. When a load strikes a gelatin gel containing 20% starch, the peak impact force is reduced by 25% when compared to a bare gel without the starch. Correspondingly, the coefficient of restitution (COR) is also lowered by the presence of starch (e.g., a ball bounces less on a starch-bearing gel). The impact-absorbing effects of starch granules are correlated to their ability to shear-thicken water. When starch granules are gelatinized by heat, they no longer give rise to shear-thickening, and in turn, their protective ability in a gel is also eliminated.

A platform, system, and method for simulating critical rock collapse of surrounding rock in underground engineering includes: four vertically arranged reaction walls defining a square reaction space, and a base mounted at a lower end opening of the wall; and a row of horizontally arranged stress loading plates at a side of each wall close to the reaction space, and a reaction beam above this space, where the reaction beam, the stress loading plate, and the base define a loading space, and the loading space is configured for placement of a surrounding rock simulation block to be tested; the stress loading plate capable of moving horizontally in a direction of the reaction wall, and the reaction beam capable of moving in a vertical direction, so as to load the surrounding rock simulation block; and the stress loading plate and the reaction beam being driven by linear motion units for movement.

A platform, system, and method for simulating critical rock collapse of surrounding rock in underground engineering includes: four vertically arranged reaction walls defining a square reaction space, and a base mounted at a lower end opening of the wall; and a row of horizontally arranged stress loading plates at a side of each wall close to the reaction space, and a reaction beam above this space, where the reaction beam, the stress loading plate, and the base define a loading space, and the loading space is configured for placement of a surrounding rock simulation block to be tested; the stress loading plate capable of moving horizontally in a direction of the reaction wall, and the reaction beam capable of moving in a vertical direction, so as to load the surrounding rock simulation block; and the stress loading plate and the reaction beam being driven by linear motion units for movement.

Provided is a hammering test system. A hammering test system includes a hammering test device including a target, a traveling mechanism for automatically traveling on a to-be-tested surface, a marking mechanism configured to perform marking on the to-be-tested surface, an adsorbing mechanism for adsorbing to the to-be-tested surface, and a hammering test mechanism configured to conduct a hammering test on the to-be-tested surface, and a surveying instrument capable of performing automatic tracking and distance and angle measurements of the target. A hammering test is conducted by causing the hammering test device to travel to a desired position while adsorbing to a to-be-tested surface by the adsorbing mechanism. When it is determined that there is an abnormality, a marking is marked on the to-be-tested surface. The surveying instrument automatically tracks the target, and when conducting a hammering test, makes distance and angle measurements of the target.

Provided is a hammering test system. A hammering test system includes a hammering test device including a target, a traveling mechanism for automatically traveling on a to-be-tested surface, a marking mechanism configured to perform marking on the to-be-tested surface, an adsorbing mechanism for adsorbing to the to-be-tested surface, and a hammering test mechanism configured to conduct a hammering test on the to-be-tested surface, and a surveying instrument capable of performing automatic tracking and distance and angle measurements of the target. A hammering test is conducted by causing the hammering test device to travel to a desired position while adsorbing to a to-be-tested surface by the adsorbing mechanism. When it is determined that there is an abnormality, a marking is marked on the to-be-tested surface. The surveying instrument automatically tracks the target, and when conducting a hammering test, makes distance and angle measurements of the target.