The present invention provides a standard testing methodology for making quantitative determinations as to the chemical resistance of thermoplastics commonly used for non-disposable medical devices by evaluating the retention of tensile and/or impact properties of the thermoplastic materials after exposure to chemicals associated with healthcare grade disinfectants. Versions of the test methods may be used with any of a variety of different thermoplastic materials, each having a different stiffness or elastic modulus; and versions of the test methods may be used with any of a variety of different hospital grade cleaning agents or disinfectants. Using the methodology of embodiments of the present invention, different thermoplastic materials may be tested against different cleaners or disinfectants to provide a uniform basis for comparison. This allows those who make chemicals, polymers and medical equipment to have a uniform way of evaluating those materials for compatibility with various cleaners and disinfectants used in the medical industry to make objective comparisons, and to allow end users to make the same evaluations and comparisons.

The present invention provides a standard testing methodology for making quantitative determinations as to the chemical resistance of thermoplastics commonly used for non-disposable medical devices by evaluating the retention of tensile and/or impact properties of the thermoplastic materials after exposure to chemicals associated with healthcare grade disinfectants. Versions of the test methods may be used with any of a variety of different thermoplastic materials, each having a different stiffness or elastic modulus; and versions of the test methods may be used with any of a variety of different hospital grade cleaning agents or disinfectants. Using the methodology of embodiments of the present invention, different thermoplastic materials may be tested against different cleaners or disinfectants to provide a uniform basis for comparison. This allows those who make chemicals, polymers and medical equipment to have a uniform way of evaluating those materials for compatibility with various cleaners and disinfectants used in the medical industry to make objective comparisons, and to allow end users to make the same evaluations and comparisons.

A test result of a tensile test and a measurement result of a natural frequency are easily associated with each other. A high-speed tensile testing machine 1 is a tensile testing machine that executes a tensile test by applying a test force F to a test target TP. The machine includes: a determination unit 513 that determines a timing at which a striking force FD is applied to a testing machine body 2; a striking structure 60 that applies the striking force FD to the testing machine body 2 at the timing determined by the determination unit 513; a first detection unit 514 that detects a vibration of the testing machine body 2 generated by the striking force FD; a calculation unit 515 that calculates a natural frequency FA of the high-speed tensile testing machine 1 on the basis of a detection result of the first detection unit 514; an execution instruction unit 516 that executes the tensile test; and a recording unit 517 that writes, in a result storage unit 518, information indicating a test result of the tensile test in association with information indicating the natural frequency FA. The timing is included in either before or after the tensile testing machine 1 executes the tensile test.

A stress-strain curve simulation method, for calculating a simulated stress-strain curve of a test object sandwiched between a mass block and a testing platform, the method comprises: obtaining a first acceleration curve associated with a plurality of pieces of acceleration data of the mass block and a second acceleration curve associated with a plurality of pieces of acceleration data of the testing platform; extracting a part of the first acceleration curve and a part of the second acceleration curve to obtain a first valid curve and a second valid curve; obtaining an object strain curve according to the first valid curve and the second valid curve; calculating an object stress curve based on the first valid curve and a contact area between the mass block and the test object; and calculating the simulated stress-strain curve based on the object strain curve and the object stress curve.

An impact test apparatus includes a base plate having an upper surface on which a specimen is placed, a collision member that collides with the specimen, a dropping unit that drops the collision member from an upper area of the specimen to the specimen and adjusts a height that the collision member drops, a velocity measurement unit that measures a collision velocity of the collision member when the collision member collides with the specimen, and an evaluation unit that produces a representative value that is a collision velocity at which a probability of breakage of the specimen is about 50%, and evaluates an impact resistance of the specimen based on the representative value.

An impact test apparatus includes a base plate having an upper surface on which a specimen is placed, a collision member that collides with the specimen, a dropping unit that drops the collision member from an upper area of the specimen to the specimen and adjusts a height that the collision member drops, a velocity measurement unit that measures a collision velocity of the collision member when the collision member collides with the specimen, and an evaluation unit that produces a representative value that is a collision velocity at which a probability of breakage of the specimen is about 50%, and evaluates an impact resistance of the specimen based on the representative value.

In one aspect, a method for conducting a drop test of an article with one or more target parameters can include dropping the article and a drop carriage of a drop tower from an initial height with respect to a base of the drop tower for an initial drop test. The article can be coupled to the drop carriage. The method can include detecting accelerometer data with respect to the article for an initial impact between the drop carriage and the base of the drop tower; determining a constant energy balance curve; determining, based on the constant energy balance curve and a target pulse duration, a target complex stiffness and/or a target total weight; adjusting, based on the target complex stiffness or the target total weight, the complex stiffness and/or the total weight for a subsequent drop test; and conducting the subsequent drop test.

In one aspect, a method for conducting a drop test of an article with one or more target parameters can include dropping the article and a drop carriage of a drop tower from an initial height with respect to a base of the drop tower for an initial drop test. The article can be coupled to the drop carriage. The method can include detecting accelerometer data with respect to the article for an initial impact between the drop carriage and the base of the drop tower; determining a constant energy balance curve; determining, based on the constant energy balance curve and a target pulse duration, a target complex stiffness and/or a target total weight; adjusting, based on the target complex stiffness or the target total weight, the complex stiffness and/or the total weight for a subsequent drop test; and conducting the subsequent drop test.

A method of determining shear strength of soil using a fall cone apparatus is provided. The method includes generating a first plot having graph lines defined for penetration depth values ranging from 4 to 20 mm on a first logarithmic paper, deducing a first mathematical model based on the first plot, and generating a second plot having the graph lines extended for a predefined penetration depth range based on the first mathematical model. The method further includes generating a third plot having graph lines corresponding to the extended penetration depth values defined for the W/A ratio values ranging from 0.17 to 13.3 on a second logarithmic paper, deducing a second mathematical model based on the third plot, generating a fourth plot having the graph lines extended for a predefined W/A ratio range based on the second mathematical model, and determining shear strength based on the fourth plot.

A method of determining shear strength of soil using a fall cone apparatus is provided. The method includes generating a first plot having graph lines defined for penetration depth values ranging from 4 to 20 mm on a first logarithmic paper, deducing a first mathematical model based on the first plot, and generating a second plot having the graph lines extended for a predefined penetration depth range based on the first mathematical model. The method further includes generating a third plot having graph lines corresponding to the extended penetration depth values defined for the W/A ratio values ranging from 0.17 to 13.3 on a second logarithmic paper, deducing a second mathematical model based on the third plot, generating a fourth plot having the graph lines extended for a predefined W/A ratio range based on the second mathematical model, and determining shear strength based on the fourth plot.