Abstract: To provide a golf club head which is easy-to-hit and which restrains the reduction of flight distance at the time of off-center shot to the minimum without making a sacrifice of the flight distance at the time of sweet spot shot, and a method for manufacturing the golf club head, a golf club head (1) has a hollow structure including a face portion (2) and a body portion (6), the body portion (6) includes a ring-shaped body barrel portion (26) as a front portion, and a tail portion (27) as a rear portion, and the average thickness of the body barrel portion (26) is 0.1 to 0.6 mm, and the mass of the tail portion (27) including a weight portion (8) is 20 to 70 g. The relations kb/kf?3 and 2 kN/mm?1/(1/kb+1/kf)?5 kN/mm are satisfied where kf (kN/mm) is the rigidity of the face portion (2) and kb (kN/mm) is the rigidity of the body barrel portion (26).

Abstract: A titanium alloy composite material including dispersed carbon fibers coated with a layer containing an element which forms a carbide in reaction with carbon, and the carbide formed thereby, in crystal grains of the titanium alloy. The element which forms a carbide in reaction with carbon is preferably at least one of silicon (Si), chromium (Cr), titanium (Ti), vanadium (V), tantalum (Ta), molybdenum (Mo), zirconium (Zr), boron (B), and calcium (Ca). The carbon fibers are preferably carbon nanotubes, vapor-grown carbon fibers, or a mixture thereof. The titanium alloy composite material has excellent mechanical strength, such as tensile strength, Young's modulus, toughness, and hardness.

Abstract: A method of producing a titanium alloy composite material comprises mixing carbon fibers and a powder of an element which forms a carbide in reaction with carbon, subliming the element under high temperature vacuum, and coating the carbon fibers with a layer containing the element and the carbide to produce coated carbon fibers. The method further comprises mixing the coated carbon fibers and titanium alloy powder to form a mixture, and applying a mechanical impact force to the mixture to fix the carbon fibers on the surface of the titanium alloy powder to obtain a carbon fiber-fixed titanium alloy powder. The method further comprises sintering the carbon fiber-fixed titanium alloy powder to form a sintered body and plastic working the sintered body to disperse the carbon fibers in crystal grains of the titanium alloy.

Abstract: To provide a golf club head which is easy-to-hit and which restrains the reduction of flight distance at the time of off-center shot to the minimum without making a sacrifice of the flight distance at the time of sweet spot shot, and a method for manufacturing the golf club head, a golf club head (1) has a hollow structure including a face portion (2) and a body portion (6), the body portion (6) includes a ring-shaped body barrel portion (26) as a front portion, and a tail portion (27) as a rear portion, and the average thickness of the body barrel portion (26) is 0.1 to 0.6 mm, and the mass of the tail portion (27) including a weight portion (8) is 20 to 70 g. The relations kb/kf?3 and 2 kN/mm?1/(1/kb+1/kf)?5 kN/mm are satisfied where kf (kN/mm) is the rigidity of the face portion (2) and kb (kN/mm) is the rigidity of the body barrel portion (26).

Abstract: A titanium alloy composite material including dispersed carbon fibers coated with a layer containing an element which forms a carbide in reaction with carbon, and the carbide formed thereby, in crystal grains of the titanium alloy. The element which forms a carbide in reaction with carbon is preferably at least one of silicon (Si), chromium (Cr), titanium (Ti), vanadium (V), tantalum (Ta), molybdenum (Mo), zirconium (Zr), boron (B), and calcium (Ca). The carbon fibers are preferably carbon nanotubes, vapor-grown carbon fibers, or a mixture thereof. The titanium alloy composite material has excellent mechanical strength, such as tensile strength, Young's modulus, toughness, and hardness.

Abstract: A damping structure which dispenses of the connection of a resistor used for a conventional damping structure and undergoes diverse molding processings with a simpler structure, and a laminate damping base material constituting such a damping structure. A laminate damping base material made of a piezoelectric ceramic material or piezoelectric polymer material and a conductive fiber-reinforced plastic (FRP) composition is prepared. One to a plurality of this base material are stacked to constitute a first damping structure. A second damping structure is constituted by stacking at least a layer of piezoelectric polymer film or piezoelectric ceramic thin film between a multilayer laminate that is a laminate of conductive laminate FRP base materials.

Abstract: A damping structure which dispenses of the connection of a resistor used for a conventional damping structure and undergoes diverse molding processings with a simpler structure, and a laminate damping base material constituting such a damping structure. A laminate damping base material made of a piezoelectric ceramic material or piezoelectric polymer material and a conductive fiber-reinforced plastic (FRP) composition is prepared. One to a plurality of this base material are stacked to constitute a first damping structure. A second damping structure is constituted by stacking at least a layer of piezoelectric polymer film or piezoelectric ceramic thin film between a multilayer laminate that is a laminate of conductive laminate FRP base materials.

Abstract: A swing training device is disclosed, which comprises a shaft part 14 having a grip part 11 formed as grip on the surface, and a pendulum part 12 extending from the forward end of the shaft part 14 and having flexibility and restoring elasticity for restoration to a substantially straight state. The grip part 11 and the shaft part 14 can be formed as separate parts, and the shaft part 14 may be disposed in the sole inside of the grip part 11.