Customer
Our client is the French Institute of Transport, Planning and Networks Sciences and Technologies (IFSTTAR). IFSTTAR is a major player in European research in various fields such as transport and infrastructure. Among other things, they study the mechanical behaviour of the human body.
Tested product
Crash test dummies simulating adult male and female bodies
Objective
Reproduce automobile impact on mannequins or representative samples of limbs or elements of the human body (e.g. bones). The aim is to measure the effects of the impact in order to model them numerically.
Problematic issues
To generate a high speed shock (up to 15m/s), with great precision and regularity of speed despite a high thrust force (up to 20000N), corresponding to a very high instantaneous power.
Acceleration and braking must be almost immediate.
Solution and result
The fast loading machine has been custom designed by LF Technologies to meet the customer's specifications and guarantee the safety of the operators.
An electric motor drives a flywheel, which is connected to a hydraulic pump that transfers up to 110 cm3 of oil per revolution. The flywheel stores a large amount of energy, allowing an instantaneous power of up to 200 kW. The oil is fed symmetrically into a system of directional cylinders to ensure equivalent operation in traction and compression. A quick-acting valve system ensures very high acceleration and rapid braking.
The impact cylinders are 4 in number and operate in pairs diagonally. The use of one pair of cylinders allows high speeds, the use of both pairs allows higher force. The jacks are connected to each other by means of alloy flanges, which are connected to a double position measuring system (absolute measurement and incremental measurement at high speed). The whole assembly consisting of the cylinders can be rotated by 90° around a horizontal axis.
In order to guarantee the safety of the operators, the machine is equipped in several places with protective housings, a light and sound signal (warning of an imminent shot/impact), and a remote emergency stop button allowing a remote operator to cut off the power in case of emergency.
The height and orientation of the impactor can also be adjusted using the control PC, which can also be remote controlled. The cylinders can be used in traction or compression in several possible configurations.
