A window drop test apparatus includes a support protruding in a first direction from the prop, and a guide portion that defines a drop space together with the support, where a drop test is performed through the drop space.

A window drop test apparatus includes a support protruding in a first direction from the prop, and a guide portion that defines a drop space together with the support, where a drop test is performed through the drop space.

Provided is a system for measuring rigidity characteristics that measures a CT value of a golf club head based on an acceleration occurring in an impactor when the impactor is caused to strike the golf club head. Correlation data is calculated by measuring a representative CT value of the golf club head, which is calculated based on CT values measured multiple times by changing the impact velocity of the impactor, and a test velocity CT value, which is a CT value when the impact velocity is set to a predetermined test velocity, for each of a plurality of the golf club heads of an identical model. A rigidity characteristic value measuring device measures the test velocity CT value for another golf club head of the model. A computer estimates the representative CT value of the other golf club head based on the test velocity CT value and the correlation data.

Provided is a system for measuring rigidity characteristics that measures a CT value of a golf club head based on an acceleration occurring in an impactor when the impactor is caused to strike the golf club head. Correlation data is calculated by measuring a representative CT value of the golf club head, which is calculated based on CT values measured multiple times by changing the impact velocity of the impactor, and a test velocity CT value, which is a CT value when the impact velocity is set to a predetermined test velocity, for each of a plurality of the golf club heads of an identical model. A rigidity characteristic value measuring device measures the test velocity CT value for another golf club head of the model. A computer estimates the representative CT value of the other golf club head based on the test velocity CT value and the correlation data.

A seat belt test apparatus for testing a safety restraint system for a vehicle comprises a first, a second, and a third test stand, an impactor apparatus, and a resistor apparatus. The first, a second, and a third test stand are selectively fixed to a test bench. The first, second and third test stands each comprises a pulley disposed proximate a top end of each of the first, second, and third test stand. The first test stand further comprises a first pretensioner mount. The third test stand further comprises a second pretensioner mount.

A seat belt test apparatus for testing a safety restraint system for a vehicle comprises a first, a second, and a third test stand, an impactor apparatus, and a resistor apparatus. The first, a second, and a third test stand are selectively fixed to a test bench. The first, second and third test stands each comprises a pulley disposed proximate a top end of each of the first, second, and third test stand. The first test stand further comprises a first pretensioner mount. The third test stand further comprises a second pretensioner mount.

A method for testing a helmet for effectiveness of user protection includes moving a load along a predetermined path, supporting a target body at an impact location in the predetermined path, the target body including a head model and a helmet disposed on the head model, and impacting the target body with a force generated by the moving of the load. The impacting of the target body entails contacting the target body with an impactor free to move perpendicularly and tangentially relative to a surface of the target body. The supporting of the target body is at least reduced, if not eliminated, before or during the impact of the impactor with the target body at the location. Forces generated are automatically measured or sensed during the impact of the impactor with the target body at the location.

A method for testing a helmet for effectiveness of user protection includes moving a load along a predetermined path, supporting a target body at an impact location in the predetermined path, the target body including a head model and a helmet disposed on the head model, and impacting the target body with a force generated by the moving of the load. The impacting of the target body entails contacting the target body with an impactor free to move perpendicularly and tangentially relative to a surface of the target body. The supporting of the target body is at least reduced, if not eliminated, before or during the impact of the impactor with the target body at the location. Forces generated are automatically measured or sensed during the impact of the impactor with the target body at the location.

Provided are a striking device and a natural frequency measuring device capable of simply and accurately measuring a natural frequency of a system including force detector. The striking device includes an arm capable of swinging around a spindle, and a steel ball arranged in an end part of the arm on a side opposite to the spindle. The spindle is supported by a supporting part capable of lifting up and down relative to a post erected on a magnet stand. A supporting part for supporting a supporting plate is arranged at a position in the post and above the supporting part. A permanent magnet is placed above the supporting plate. The steel ball falls down in an arc shape from a standby height position when the permanent magnet is removed.

A method for preparing a SiC ingot includes: disposing a raw material and a SiC seed crystal facing each other in a reactor having an internal space; subliming the raw material by controlling a temperature, a pressure, and an atmosphere of the internal space; growing the SiC ingot on the seed crystal; and collecting the SiC ingot after cooling the reactor. The wafer prepared from the ingot, which is prepared from the method, generates cracks when an impact is applied to a surface of the wafer, the impact is applied by an external impact source having mechanical energy, and a minimum value of the mechanical energy is 0.194 J to 0.475 J per unit area (cm.sup.2).