A resonant column device configured to perform a resonant column test on a specimen and measure an angular deformation of the specimen. The resonant column device has a housing mounted on a base, a specimen container within the housing, a cell wall surrounding the specimen container, a load frame within the housing with a support bar above the specimen container, a torque motor suspended from the support bar with a plurality of springs, and a laser deformation sensor within the housing outside of the specimen container. The specimen container is configured to hold the specimen during testing. The cell wall is configured to fluidly isolate the specimen container from an interior volume of the housing. The torque motor is configured to apply a torsional harmonic load to the specimen, and the laser deformation sensor is configured to measure an angular deformation of the specimen.

A friction test device based on a torsional Hopkinson bar (THB) includes a base, a baffle, and pull rods. The servo axial loading device includes a first oil pressure tank and a first pressure rod. One end of the first pressure rod is embedded in the first oil pressure tank. The baffle includes a front baffle and a rear baffle. The pull rods are arranged between the front baffle and the rear baffle. A loading guide rod is provided between the front baffle and the rear baffle. The rear baffle is fixed thereon with a constraint mass. The loading guide rod includes one end connected to the first pressure rod and the other end connected to the constraint mass through a specimen. The friction test device further includes a torque application device and a torque storage device. Therefore, the specimen undergoes a full friction process from static to dynamic.

A friction test device based on a torsional Hopkinson bar (THB) includes a base, a baffle, and pull rods. The servo axial loading device includes a first oil pressure tank and a first pressure rod. One end of the first pressure rod is embedded in the first oil pressure tank. The baffle includes a front baffle and a rear baffle. The pull rods are arranged between the front baffle and the rear baffle. A loading guide rod is provided between the front baffle and the rear baffle. The rear baffle is fixed thereon with a constraint mass. The loading guide rod includes one end connected to the first pressure rod and the other end connected to the constraint mass through a specimen. The friction test device further includes a torque application device and a torque storage device. Therefore, the specimen undergoes a full friction process from static to dynamic.

A dynamic friction experimental device includes a base, an incident bar, an axial compression device, and a torque loading device. The base is provided with a displacement-constrain structure, and the incident bar includes a first incident section and a second incident section. The first incident section is arranged adjacent to the displacement-constrain structure, and the second incident section is connected to the first incident section. At a joint of the first incident section and the second incident section, a projection of a cross section of the first incident section is positioned in a cross section of the second incident section along an axial direction of the second incident section. When the dynamic mechanical property of a specimen is tested, the axial compression device is configured to apply pressure to the second incident section, and the torque loading device is configured to apply torque to the second incident section.

A dynamic friction experimental device includes a base, an incident bar, an axial compression device, and a torque loading device. The base is provided with a displacement-constrain structure, and the incident bar includes a first incident section and a second incident section. The first incident section is arranged adjacent to the displacement-constrain structure, and the second incident section is connected to the first incident section. At a joint of the first incident section and the second incident section, a projection of a cross section of the first incident section is positioned in a cross section of the second incident section along an axial direction of the second incident section. When the dynamic mechanical property of a specimen is tested, the axial compression device is configured to apply pressure to the second incident section, and the torque loading device is configured to apply torque to the second incident section.

The disclosure provides compositions and methods for making a colorized solution of an aqueous disinfectant that is both stable in bulk solution and will fade to clear within a predetermined period of time after being applied to a surface, for example as a spray or film. The compositions and methods described here allow an end user to visualize both the extent of coverage and the duration of contact of the disinfectant with the surface, thereby providing more efficient disinfection of the surface.

A racquet including a frame including a head portion, a handle portion, and a throat portion. The head portion is a tubular structure including inner and outer peripheral walls, each having inner and outer surfaces. The head portion of the racquet being formed of a fiber composite material. The fiber composite material includes a plurality of ply arrangements. Each includes a pair of plies defining first and second angles with respect to a composite axis. A section of the outer peripheral wall from the inner surface to the outer surface includes at least three ply arrangements overlaying each other, and the first and second angles of at least two of the at least three ply arrangements being at least 35 degrees. When the racquet is tested under a racquet torsional stability test, the racquet has an angular deflection of less than 5.5 degrees about a longitudinal axis.

A racquet including a frame including a head portion, a handle portion, and a throat portion. The head portion is a tubular structure including inner and outer peripheral walls, each having inner and outer surfaces. The head portion of the racquet being formed of a fiber composite material. The fiber composite material includes a plurality of ply arrangements. Each includes a pair of plies defining first and second angles with respect to a composite axis. A section of the outer peripheral wall from the inner surface to the outer surface includes at least three ply arrangements overlaying each other, and the first and second angles of at least two of the at least three ply arrangements being at least 35 degrees. When the racquet is tested under a racquet torsional stability test, the racquet has an angular deflection of less than 5.5 degrees about a longitudinal axis.

A racquet including a frame including a head portion, a handle portion, and a throat portion. The head portion forms a hoop that defines a string bed plane. The head portion of the racquet being formed of a fiber composite material. When the racquet is tested under a racquet forward/rearward bending test, the racquet has a forward/rearward deflection with respect to the longitudinal axis of at least 8.5 mm when measured in a direction that is perpendicular to the string bed plane and perpendicular to the longitudinal axis. When the racquet is tested under a racquet torsional stability test, the racquet has an angular deflection of less than 5.5 degrees about a longitudinal axis.

A racquet including a frame including a head portion, a handle portion, and a throat portion. The head portion forms a hoop that defines a string bed plane. The head portion of the racquet being formed of a fiber composite material. When the racquet is tested under a racquet forward/rearward bending test, the racquet has a forward/rearward deflection with respect to the longitudinal axis of at least 8.5 mm when measured in a direction that is perpendicular to the string bed plane and perpendicular to the longitudinal axis. When the racquet is tested under a racquet torsional stability test, the racquet has an angular deflection of less than 5.5 degrees about a longitudinal axis.