The invention relates to a ball game racket frame (12) including a head portion (14), a shaft portion (18) and a grip portion (20). The ball game racket frame (12) comprises a fiber composite material having fibers embedded in a matrix. At least 5% of the fibers are natural fibers in at least one cross-section (28, 28a, 28b, 28c, 28d, 28e) of a portion of the ball game racket frame (12).

The invention further relates to a ball game racket frame (12) in which the proportion of natural fibers in at least one cross-section (28b, 28c, 28d, 28e) of the shaft portion (18) and/or the grip portion (20), respectively, is greater than the proportion of natural fibers in at least one cross-section (28, 28a) of the head portion (14).

The invention further relates to a method for manufacturing such ball game racket frames (12).

The invention relates to a ball game racket frame (12) including a head portion (14), a shaft portion (18) and a grip portion (20). The ball game racket frame (12) comprises a fiber composite material having fibers embedded in a matrix. At least 5% of the fibers are natural fibers in at least one cross-section (28, 28a, 28b, 28c, 28d, 28e) of a portion of the ball game racket frame (12).

The invention further relates to a ball game racket frame (12) in which the proportion of natural fibers in at least one cross-section (28b, 28c, 28d, 28e) of the shaft portion (18) and/or the grip portion (20), respectively, is greater than the proportion of natural fibers in at least one cross-section (28, 28a) of the head portion (14).

The invention further relates to a method for manufacturing such ball game racket frames (12).

A shock absorbing structure of a racket contains: a head and an absorption member matingly contacting with an internal fence of the head. The absorption member is a hollowly tubular structure and covers the internal fence totally. When the head is made of carbon-fiber composite material, the absorption member is made of any one of Thermoplastic Elastomer (TPE), Thermoplastic Rubber (TPR), rubber, Hydrogel, and Thermoplastic Polyurethane (TPU). When the head is made of metal or aluminum alloy, the absorption member is made of any one of Thermosetting Elastomers, Thermoplastic Elastomer (TPE), Thermoplastic Rubber (TPR), rubber, Hydrogel, and Thermoplastic Polyurethane (TPU). When the head and the absorption member are made of different materials, an amplitude of the head is different from an amplitude of the absorption member, and the head interferes the absorption member, thus absorbing vibration.

A shock absorbing structure of a racket contains: a head and an absorption member matingly contacting with an internal fence of the head. The absorption member is a hollowly tubular structure and covers the internal fence totally. When the head is made of carbon-fiber composite material, the absorption member is made of any one of Thermoplastic Elastomer (TPE), Thermoplastic Rubber (TPR), rubber, Hydrogel, and Thermoplastic Polyurethane (TPU). When the head is made of metal or aluminum alloy, the absorption member is made of any one of Thermosetting Elastomers, Thermoplastic Elastomer (TPE), Thermoplastic Rubber (TPR), rubber, Hydrogel, and Thermoplastic Polyurethane (TPU). When the head and the absorption member are made of different materials, an amplitude of the head is different from an amplitude of the absorption member, and the head interferes the absorption member, thus absorbing vibration.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and −1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and −1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and −1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and −1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

An object of the present invention is to provide a novel fiber-reinforced epoxy resin material having improved strength. The fiber-reinforced epoxy resin material of the present invention comprises a cured product of an epoxy resin composition and a reinforcing fiber, wherein the epoxy resin composition comprises a novolac type epoxy resin as an epoxy resin component, and the cured product of the epoxy resin composition has a swelling ratio in a range from 20 mass % to 44 mass % in methyl ethyl ketone.

An object of the present invention is to provide a novel fiber-reinforced epoxy resin material having improved strength. The fiber-reinforced epoxy resin material of the present invention comprises a cured product of an epoxy resin composition and a reinforcing fiber, wherein the epoxy resin composition comprises a novolac type epoxy resin as an epoxy resin component, and the cured product of the epoxy resin composition has a swelling ratio in a range from 20 mass % to 44 mass % in methyl ethyl ketone.

The present invention relates to a ball game racket frame with a head portion and a handle portion, wherein the ball game racket frame comprises a fiber composite with at least one multi-fiber roving that is at least partially twisted.

The present invention relates to a ball game racket frame with a head portion and a handle portion, wherein the ball game racket frame comprises a fiber composite with at least one multi-fiber roving that is at least partially twisted.