Virtual Stability Simulation of a Telescopic Handler Machine According to the Standard UNI EN 1459.

INTRODUCTION
We have developed a multi-body model in order to simulate the stability behavior of a telescopic handler under different load conditions, elongation and rotation of the boom. Lateral stability on telescopic handlers is difficult to be predicted as many physical variables like flexural and torsional stiffness, hydraulics limits, sliding parts mass distribution, clearance, inertia are involved in.

When machine is flat on the ground the weight distribution and center of gravity can be evaluated immediately, while, when machine is on inclined platform, as per standard EN1459, a multi-body tool can manage all the physical and kinematic variables.

METHODOLOGY
A multi-body model based on concentrated masses has been implemented using Altair Motion View/Motion Solve tool. The model contains the kinematics of boom with sliding arms, the tires deflection radii and deformation, the inertial properties of boom arms and the evaluation of the deflection effect on the arms. Multibody model consists of a simplified frame, including tires and axles, boom divided in different sliding arms and forks. An additional component simulating stabilizers has been used in order to increase the lifting performance.

Finally a DOE (Design of experiment) like approach was used to generate different rotational angles and elongation of the boom, max applied load up to stability limit, max hydraulic performance in lifting operation, reaction forces on each contact to the ground (tires or stabilizers).

RESULTS
This multi-body approach was considered useful to speed up the product design and its physical validation, because it is able to cover all the range of positions in horizontal reach or height with the maximum payload permitted while the physical tests investigate only few critical positions.

Multi-body model has a user friendly interface and can be quickly modified to analyze a machine with different number of sliding arms.

The multi-body model has been validated with physical correlation activities using current production machines. This validated model will be used for the future product development.

 

The Author

Ing. Stefano Largo
Design Analysis & Simulation
CNH Italia S.p.A.