A method and apparatus for improving the accuracy and precision of drop impact sensing data utilized for testing the impact-absorbing capacities of surfaces, especially playground surfaces used by children, for compliance with relevant standards. A head form missile is equipped with onboard sets of high-g and low-g accelerometers for timing a period of free-fall of the missile, as well as for measuring acceleration due to impact at the end of the fall. Optimized results are obtained in a preferred embodiment by exploiting at least four accelerometers. Three of the accelerometers are sized for high-g measurements in each axis (X-, Y-, and Z-axes). At least one low-g accelerometer for (measuring in the Z-axis), or three accelerometers sized for low-g measurements in all axis (X-, Y- and Z-axes) are employed. Accelerometer readings obtained during the zero g free-fall period is used to cancel bias drift on all accelerometers.

A method and apparatus for improving the accuracy and precision of drop impact sensing data utilized for testing the impact-absorbing capacities of surfaces, especially playground surfaces used by children, for compliance with relevant standards. A head form missile is equipped with onboard sets of high-g and low-g accelerometers for timing a period of free-fall of the missile, as well as for measuring acceleration due to impact at the end of the fall. Optimized results are obtained in a preferred embodiment by exploiting at least four accelerometers. Three of the accelerometers are sized for high-g measurements in each axis (X-, Y-, and Z-axes). At least one low-g accelerometer for (measuring in the Z-axis), or three accelerometers sized for low-g measurements in all axis (X-, Y- and Z-axes) are employed. Accelerometer readings obtained during the zero g free-fall period is used to cancel bias drift on all accelerometers.

A device for measuring strength and strain softening parameters of a saturated clay sample based on full-flow penetration belongs to the technical field of geotechnical, geological and environmental research. The device mainly comprises two parts: an overlying pressure loading system and a full-flow penetration system. The present invention mainly aims at the problem of incomplete backflow of the soil in the measurement of soil strength and strain softening parameters with a full-flow penetrometer for saturated clay, and applies the working principle of a traditional consolidometer to vertically pressurize a soil sample to ensure the backflow of the soil, thereby improving the applicability of the full-flow penetrometer in the measurement aspect of the soil strength and the strain softening parameters and having important practical value for test research and marine engineering design.

A device for measuring strength and strain softening parameters of a saturated clay sample based on full-flow penetration belongs to the technical field of geotechnical, geological and environmental research. The device mainly comprises two parts: an overlying pressure loading system and a full-flow penetration system. The present invention mainly aims at the problem of incomplete backflow of the soil in the measurement of soil strength and strain softening parameters with a full-flow penetrometer for saturated clay, and applies the working principle of a traditional consolidometer to vertically pressurize a soil sample to ensure the backflow of the soil, thereby improving the applicability of the full-flow penetrometer in the measurement aspect of the soil strength and the strain softening parameters and having important practical value for test research and marine engineering design.

The present invention provides a projectile for use in a simulated fan-blade-off ballistic test. The projectile has an ellipsoid body having a blind axial bore extending from a first axial end. The blind axial bore is for housing a weight adjustment body which can be used to modify the weight and/or centre of gravity of the projectile. A sealing plug may seal the weight adjustment body within the axial bore and an insert may be provided to fix the position of the weight adjustment body and/or to control the sliding of the weight adjustment body within the axial bore.

According to the present technology, an impact test in which an impact application member is made to free fall onto a test sample of a plurality of types of rubbers having different physical properties is performed under prescribed test conditions; data for at least one of three items including a loss energy that is absorbed by the test sample when the impact application member collides with the test sample, a thermal energy that is generated at the test sample, and an indentation amount into the test sample by the impact application member is acquired; and an optimal test sample is selected from the respective test samples on a basis of a ranking of the superiority of the respective test samples with respect to the item(s) for which data was acquired.

According to the present technology, an impact test in which an impact application member is made to free fall onto a test sample of a plurality of types of rubbers having different physical properties is performed under prescribed test conditions; data for at least one of three items including a loss energy that is absorbed by the test sample when the impact application member collides with the test sample, a thermal energy that is generated at the test sample, and an indentation amount into the test sample by the impact application member is acquired; and an optimal test sample is selected from the respective test samples on a basis of a ranking of the superiority of the respective test samples with respect to the item(s) for which data was acquired.

A geotechnical apparatus comprising a holder with a coiled rod with a probe, such as a penetrometer, a rod bending/straightening device and a drive unit for both uncoiling the coiled continuous rod and pushing the uncoiled rod with the probe into the ground and for pulling such a rod with the probe out of the ground and recoiling the continuous rod, wherein the drive unit comprises two grippers to alternatingly grip the rod and move it along its longitudinal axis over a predefined length, the bending/straightening device has a first set of rollers, at least two of which are at one side of the rod and the remaining rollers are at an opposing side of the rod, such that the rollers convert the coiled rod to an essentially straight rod when uncoiling and convert the straight rod to a coiled rod of essentially constant coil diameter when coiling.

A geotechnical apparatus comprising a holder with a coiled rod with a probe, such as a penetrometer, a rod bending/straightening device and a drive unit for both uncoiling the coiled continuous rod and pushing the uncoiled rod with the probe into the ground and for pulling such a rod with the probe out of the ground and recoiling the continuous rod, wherein the drive unit comprises two grippers to alternatingly grip the rod and move it along its longitudinal axis over a predefined length, the bending/straightening device has a first set of rollers, at least two of which are at one side of the rod and the remaining rollers are at an opposing side of the rod, such that the rollers convert the coiled rod to an essentially straight rod when uncoiling and convert the straight rod to a coiled rod of essentially constant coil diameter when coiling.

A system for simultaneously measuring the indentation hardness properties, span properties, and resilience properties of a mattress includes a first indentation means and a second indentation means, and means for urging the first indentation means and the second indentation means into the mattress with a predetermined force, and also includes laser means for projecting a laser line configured to map, preferably by photographic triangulation, the amplitude, shape, and time-dependency of the resultant deflection of the mattress surface between the first indentation means and the second indentation means. A method for simultaneously measuring the indentation hardness properties, span properties, and resilience properties of a mattress is also provided.