An impact test fixture capable of applying preload on a composite laminate, which is composed of a base, a clamping mechanism and a loading mechanism, where the clamping mechanism is positioned on an upper surface of the base and fixedly connected to the base through a bolt, and the loading mechanism is installed at an end of the base. A composite laminate is placed in a rectangular groove of the base. A first wedge block and a second wedge block are positioned in a base sliding groove between a pressing block and a baffle plate, and inclined planes of the two wedge blocks are oppositely installed; the baffle plate is matched with the base through a first fixing bolt and a second fixing bolt, a loading bolt passes through a screw hole at a side end of the base and is matched with the first wedge block.

A method of offset load testing a tubular composite specimen with two pairs of aligned holes and having at least one defect, the method comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; securing the pair of arms using a fastener assembly in each of the two pairs of aligned holes; and moving the mobile arm to impart an offset load force to the tubular specimen. One aspect includes a method of offset load testing comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; providing a tubular composite specimen with a top portion and a bottom portion; securing the pair of arms to the top and bottom portions of the tubular composite specimen; and moving the mobile arm to impart an offset load force to the tubular composite specimen.

In an aspect, there is a method of determining allowable defects for a composite component comprising identifying at least one wrinkle characteristic of a composite component wrinkle defect; making a first plurality of specimens each having a predetermined wrinkle defect representative of the composite component wrinkle defect; measuring each of the predetermined wrinkle defects in the first plurality of specimens for at least one performance metric to generate performance data; and generating an allowable wrinkle defect profile based on the performance data from the first plurality of specimens. In other aspects, there are methods of making a specimen with a predetermined wrinkle defect.

The invention relates to a device for carrying out bending tests on panel-shaped or beam-shaped samples (1), in which two rotary drives are arranged at a distance from one another and a flange (3) is fastened to each of the drive shafts of the rotary drives, said drive shafts being oriented parallel to one another. At least two bar-shaped bending elements (2) oriented parallel to the axis of rotation of the drive shafts and arranged at a distance from the axis of rotation and at a distance from one another are provided on each of the flanges (3). A panel-shaped or beam-shaped sample (1) can be introduced between the two bar-shaped bending elements (2) on the two flanges (3). In the event of rotation of the rotary drives in opposite directions of rotation, bending forces are exerted on the sample (1) and each of the two rotary drives can be controlled individually and connected to an electronic open-loop or closed-loop control unit.

A racquet extends along a longitudinal axis and is capable of being tested under a racquet lateral bending test and a racquet torsional stability test. The racquet lateral bending test includes mounting the racquet in a first orientation to a first test fixture at a first longitudinal location, attaching a clamp to the racquet at a second location, operably engaging a deflection indicator to the clamp, applying a first predetermined weight to the racquet at a third location, and removing the first weight to obtain a lateral deflection measurement of the racquet with respect to the longitudinal axis. The racquet torsional stability test includes mounting the racquet to second and third test fixtures at sixth and seventh locations of the racquet, respectively, placing a third predetermined weight on an arm extending from the second test fixture, removing the third predetermined weight to obtain an angular deflection about the axis. The racquet comprises a frame including head and handle portions and a throat portion positioned between the head and handle portions. The head portion forms a hoop that defines a string bed plane. When the racquet is tested under the racquet lateral bending test, the racquet has a lateral deflection of at least 6.0 mm when measured in a direction that is parallel to the plane and perpendicular to the axis. When the racquet is tested under the racquet torsional stability test, the racquet has an angular deflection of less than 5.0 degrees about the axis.

A tennis racquet extending along the longitudinal axis and capable of being tested under a forward/rearward bending test and a torsional stability test includes a frame having a head portion, a handle portion, and a throat portion positioned between the head portion and the handle portion. The head portion forms a hoop that defines a string bed plane. At least the head portion and the throat portion of the racquet are formed at least in part of a fiber composite material. The throat portion includes a pair of throat elements. When the racquet is tested under the forward/rearward bending test, the racquet has a forward/rearward deflection with respect to the longitudinal axis of at least 9.0 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 the torsional stability test, the racquet has an angular deflection of less than 5.5 degrees about the longitudinal axis.

In a first aspect, there is a method of making a specimen with a predetermined wrinkle defect, the steps including orienting a composite material around a layup tool at a wrap angle to form a closed loop; and generating at least one wrinkle with a predetermined characteristic in a portion of the closed loop to form a specimen. The predetermined characteristic is at least one of the following: wrinkle location, an outward wrinkle, an inward wrinkle, a wrinkle width, a wrinkle height, and a wrinkle length. In another aspect, there is a method of determining allowable defects for a composite component.

There is a method of making a tubular specimen with a predetermined wrinkle defect including providing a layup tool with a cavity forming member having a cavity which resembles a desired shape of the at least one wrinkle; orienting a composite material around the mandrel at a wrap angle to form a closed loop; positioning a wrinkle tool on the closed loop; and/or generating at least one wrinkle with a predetermined characteristic in a portion of the closed loop to form a tubular specimen. The predetermined characteristic is at least one of the following: wrinkle location, an outward wrinkle, an inward wrinkle, a wrinkle width, a wrinkle height, and a wrinkle length. In another aspect, there is a method of offset load testing a tubular composite specimen. In a third aspect, there is a method of determining allowable defects for a composite component.

A sports racquet capable of being tested under a racquet vibration test, and including a frame extending along a longitudinal axis. The frame includes a head portion, a handle portion, and a throat portion positioned between the head portion and the handle portion. The head portion forms a hoop that defines a string bed plane. The throat portion includes a pair of throat elements. At least the head portion and the throat portion of the racquet are formed at least in part of a fiber composite material. The head portion including a forward hoop surface and a rearward hoop surface. The distance between the forward and rearward hoop surfaces defines a beam height distance. The head portion has a maximum beam height distance of at least 19 mm. When the racquet is tested under the racquet vibration test, the racquet has a vibration of no greater than 130 Hz.

A racquet includes a frame extending along a longitudinal axis. The frame includes head and handle portions, and a throat portion positioned between the head and handle portions. The head and throat portions are formed at least in part of a fiber composite material. The material includes a plurality of ply arrangements. Each of the arrangements includes one ply having a first plurality of fibers defining a first angle with respect to a composite axis, and another ply having a second plurality of fibers defining a second angle with respect to the composite axis. The first and second angles are substantially the same except the angles have opposite polarities with respect to the composite axis. The head portion includes at least three arrangements overlaying each other, and the first and second angles of at least two of the at least three arrangements are at least 35 degrees.