Accelerated impact testing apparatus

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means for allowing load and strain transients to develop in the specimen when impacted by said impactor means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) specimen protection means to prevent undesired damage to the specimen during impact,
• j) the acceleration means including a compression spring with supporting means to allow sudden expansion of the spring,
• k) there being a spring loading transition plate between the spring and the impactor means,
• l) and wherein the transition plate contains a cone shaped center for self-centering of the end of a spring compressing screw carried by the power means.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) imoactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) said power means including a motor and a force translation means which provides a linear force to compress the spring,
• k) and including an assembly that includes a ball screw and a ball nut, and wherein the motor turns said ball screw through a flexible coupling which allows said ball nut travel linearly to compress the spring.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) and including elongated guidance means, and wherein the crosshead travels vertically on the guidance means, which aligns the crosshead relative to the specimen, maintaining force application in a downward direction,
• k) and wherein the crosshead consists of lightweight metal to reduce the acceleration mass of the crosshead.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) and including elongated guidance means, and wherein the crosshead travels vertically on the guidance means, which aligns the crosshead relative to the specimen, maintaining force application in a downward direction,
• k) and including a tup and load cell assembly attached to the bottom side of the crosshead to provide a downwardly convex striking surface and to load the cell in response to such striking,
• l) and wherein the tup assembly includes a spring that provides a constant, calibrated force against a load cell.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) said acceleration means including a compression spring with supporting means to allow sudden expansion of the spring,
• k) and wherein the latching means includes a latch lever which holds up the crosshead under the loading of the spring and thereby allows the spring to store a pre-determined amount of energy, and a rotating restraining lever which is interposed between the latching lever and said crosshead, to minimize friction against the crosshead, both levers being releasable by a latch tripping means.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) said power means includes a motor and a force translation means which provides a linear force to compress the spring,
• k) and including an assembly that includes a ball screw and a ball nut, and wherein the motor turns said ball screw through a flexible coupling which allows said ball nut travel linearly to compress the spring,
• l) and including a latch tripping means that comprises a bolt that travels with the ball screw and ball nut assembly and pushes down latching means to release the latching means and allow the crosshead to move downward.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) said velocity measuring means includes a laser emitter/receiver device and a flag which travels with the crosshead into and out of registration with a beam emitted by the laser device,
• k) and wherein the control means includes a relay system, limit switches and logic circuitry to control the range of motion of the ball nut and spring and then uses the laser device to activate the load cell and strain gauge data collection sequence following which the relay is again activated to move the ball nut to its original up position.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a) a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) and wherein the specimen holding means includes two support fixtures spaced about 18 inches apart so that when the specimen is impacted a realistic stress corresponding to stress undergone by the specimen in actual use is propagated in the specimen.

An accelerated impact testing apparatus for simulating actual strains and strain rates and measuring the strain and strain rate characteristics of materials using a falling impactor to impact a specimen, and comprising:

• a crosshead, and acceleration means for applying a predetermined force to the crosshead,
• b) impactor means carried by the crosshead for striking the specimen while the impactor is traveling,
• c) specimen holding means,
• d) latching means for holding the impactor means in a first position while the acceleration means exerts initial loading transmitted to the crosshead,
• e) velocity measuring means to detect and record impactor velocity just prior to impacting the specimen,
• f) power means for driving the acceleration means,
• g) restriction means to prevent the impactor means from deflecting the specimen beyond a preset limit,
• h) control means for starting and stopping the power means, and for collecting and organizing acquired data, and
• i) means to prevent undesired damage to the specimen during impact,
• j) and wherein the specimen protection means comprises a steel sleeve which is received onto the tip of specimen to protect the specimen from damage and to ensure that the bending of the specimen is directly downward.