Impact depth

Abstract: A Micro Materials (UK) NanoTest has been modified for fast data acquisition at up to 200 kHz to enable high-resolution (sub-pJ) impact energy measurement. Displacement versus time data were acquired at 20 kHz in 3-s bursts to capture the acceleration, impact and rebounding of the pendulum-mounted indenter. The data acquired were analysed to provide measurements of position, velocity, acceleration, impact distance, impact depth (elastic and plastic) potential and kinetic energy throughout the impact cycle and provided high-resolution information throughout the impact event itself, which lasted only ∼ 10 ms. The ability of the system to detect fracture events and measure energies associated with these events is investigated. The effect of impact energy and indenter geometry is demonstrated and it is shown that the system is able to detect damage events and measure the difference in the energy absorbed in an impact when damage occurs.

Abstract: A model was developed for impacts of elastic perfectly plastic spherical particles with impact velocities up to 250 m/s. The model is based on the two master curves, for normalized pressure $$\bar{H}$$ and projected contact area c 2, which both are functions of the representative strain Λ at maximum impact. The model and its parameters were fitted to finite element results for elastic perfectly plastic and strain rate-independent materials. It was applied to a wide range of materials with different ratio between yield stress and elastic properties, different ball sizes and impact velocities. The impact model predicted the results from finite element method for contact radius, maximum impact depth in both target and ball as well as remaining impact depth in target and ball. The remaining impact depth was determined from elastic spring back with Hertzian and quadratic pressure at maximum impact. The rebound velocity was also estimated by following the load-deformation path during spring back. If the strain rate-compensated yield stress was used for the master curve parameters, then the model predicted the impact results also for the investigated strain rate-dependent materials.

Abstract: The closed head impact (CHI) rat models are commonly used for studying the traumatic brain injury. The impact parameters vary considerably among different laboratories, making the comparison of research findings difficult. In this work, numerical CHI experiments were conducted to investigate the sensitivities of intracranial responses to various impact parameters (e.g., impact depth, velocity, and position; impactor diameter, material, and shape). A three-dimensional finite element rat head model with anatomical details was subjected to impact loadings. Results revealed that impact depth and impactor shape were the two leading factors affecting intracranial responses. The influence of impactor diameter was region-specific and an increase in impactor diameter could substantially increase tissue strains in the region which located directly beneath the impactor. The lateral impact could induce higher strains in the brain than the central impact. An indentation depth instead of impact depth would be appropriate to characterize the influence of a large deformed rubber impactor. The experimentally observed velocity-dependent injury severity could be attributed to the “overshoot” phenomenon. This work could be used to better design or compare CHI experiments.

Abstract: The invention discloses a crust impact air cylinder height regulating device also called a crust impact hammer lower dead point regulating device. The crust impact air cylinder height regulating device is mainly used for regulating the height of a lower dead point of the impact motion of an aluminum electrolytic cell crust impact hammer. The crust impact air cylinder height regulating device is characterized in that a spiral lead screw height regulating device is arranged on the side face of a crust impact air cylinder, and as for the spiral lead screw height regulating device, rotation of a spiral lead screw can drive the installation fixing position of the crust impact air cylinder to move up and down so that height regulation can be achieved. The problem that as the impact depth of an impact hammer of an existing common aluminum electrolytic cell crust impact device is not in place, a fire opening filling hole in an electrolyte crusting position is difficult to form, or as the impact depth of the crust impact hammer is too large, the hammer has a lump, and the fire opening filling hole is irregular can be solved thoroughly, and unattended and maintenance-free operation of an electrolytic cell is achieved.