Dynamic analysis is used to verify the maximum and minimum loads on all belt conveyor components during all possible transient conditions of stopping and starting. It is also used to develop and test the control algorithms necessary to safely and reliability stop and start the load.
Proper dynamic analysis requires a time based, FEA solver which considers the elasticity of the belting and all the masses which make us the conveyance system.
Our engineers can provide a complete conveyor dynamic analysis for you...
What is Dynamic Analysis?
Dynamic Analyst™ is an add on module to Overland Conveyor Co's internationally renowned static analysis program; Belt Analyst™
Dynamic Analyst™ uses the same user friendly interface to input any additional information required. Never a need to input the same data twice. Input motor and brake data as well as control deceleration and acceleration curves either numerically or graphically. Use popular PID control algorithms to control devices. Model take-ups as either gravity, fixed (screw) or as a mechanical winch or hydraulic cylinder.
Quicky add points to plot.
Plot belt tensions or belt velocity at any point on the conveyor. At every drive or brake, plot power, torque and whether or not slip might occur. Evaluate low tension conditions for potential dangeous sag conditions. And plot take-up carriage displacement and velocity. Review or record animations of belt tensions and belt velocities. Animation recorded in standard Windows AVI format can be viewed on any Windows based computer.
Quickly change between Imperial or Metric units with one click.
Printout all input and output data including graphics in a clean, professional format. Also, one click and you can write a PDF document to archive or e-mail to clients or associates.
How Does Dynamic Analysis Work?
When performing starting and stopping calculations per CEMA or DIN 22101 (static analysis), it is assumed all masses are accelerated at the same time and rate; in other words the belt is a rigid body (non-elastic).
In reality, drive torque transmitted to the belt via the drive pulley creates a stress wave which starts the belt moving gradually as the wave propagates along the belt. Stress variations along the belt (and therefore elastic stretch of the belt) are caused by these longitudinal waves while being dampened by resistances to motion.
It is, therefore, important a mathematical model of the belt conveyor that takes belt elasticity into account during stopping and starting be considered in these critical, long applications.
A model of the complete conveyor system can be achieved by dividing the conveyor into a series of finite elements. Each element has a mass and rheological spring as illustrated below:
Many methods of analyzing a belt’s physical behavior as a rheological spring have been studied and various techniques have been used. An appropriate model needs to address:
- > Elastic modulus of the belt longitudinal tensile member
- > Resistances to motion which are velocity dependent (i.e. idlers)
- > Viscoelastic losses due to rubber-idler indentation
- > Apparent belt modulus changes due to belt sag between idlers
Since the mathematics necessary to solve these dynamic problems are very complex, it is not the goal of this presentation to detail the theoretical basis of dynamic analysis. Rather, the purpose is to stress that as belt lengths increase and as horizontal curves and distributed power becomes more common, the importance of dynamic analysis taking belt elasticity into account is vital to properly develop control algorithms during both stopping and starting.