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Output File: ReStackor Suspension Response Calculations

Outputs of ReStackor suspension response calculations are on the "Resp_Dat" tab of ReStackor mid-valve spreadsheets. Definitions of each output parameter are given below.

Wheel and chassis bottoming

ReStackor suspension response calculations estimate wheel bottoming velocities starting from the suspension normal ride height specified by the input parameter “race sag”. The calculations determine the initial wheel velocity needed for the combination of shock gas force, spring force and damping to stop the wheel at the specified input “Max Stroke” position. 

Suspension position and velocities from the calculations are tabulated in the “Resp_Dat” tab of the spreadsheet. The first block of output data describes the wheel position through the compression stroke. The second block of data describes the wheel rebound stroke. The third block describes the chassis bottoming stroke in compression and the final fourth block describes the chassis rebound stroke. Each block is separated by a header describing the variable name and units. In each output block the first line records the value at race sag for plotting purposes.

ReStackor suspension response output parameters

Time [=] Elapsed time from start of suspension stroke

y.wheel [=] Wheel position measured from full extension

LR [=] Suspension link ratio. Ratio of shock to wheel motion for an incremental change in y.wheel at the current suspension position

TR [=] Travel ratio. Ratio of wheel to shock travel and current y.wheel position

F.spring [=] Spring force at wheel

F.gas [=] Shock gas force at wheel

F.damp [=] Shock damping force at shock shaft

a.wheel [=] Wheel acceleration rate

u.wheel [=] Wheel velocity

u.shaft [=] Shock shaft velocity

zeta.whl [=] Suspension response zeta coefficient at current stroke position

Stroke averaged zeta response coefficient

Following the suspension response outputs ReStackor outputs the instantaneous and stroke averaged zeta value for the rebound stroke of both the wheel and chassis. Output parameters are described below:

Suspension response zeta coefficient outputs:

stroke [=] Maximum stroke depth measured from full extension

u.shaft [=] Rebound stroke velocity on return to race sag

zeta [=] Instantaneous zeta value of rebound stroke on return to race sag

zetaC [=] Averaged zeta value set to give same response time and final velocity as actual suspension

Damping Force

ReStackor suspension response calculations use the computed compression damping force for the shock extracted from the "Mid_Valve_Calc" output tab and rebound damping force from the "mvr_ReStackor" output tab. Those values are echoed in the suspension response output data along with the rebound/compression damping ratio. The output parameters are defined below:

Shock damping force outputs:

U.comp [=] Shock shaft compression velocity

C.comp [=] Shock compression damping coefficient defined as the shocks compression damping force divided by shaft velocity

U.rbnd [=] Shock shaft rebound velocity

C.rbnd [=] Shocks rebound damping coefficient

U.whl [=] Suspension wheel velocity

Damp Ratio [=] Shocks rebound/compression damping ratio at the suspension wheel velocity specified by U.whl

Maximum velocities in shock compression and rebound strokes

ReStackor suspension response calculations record the maximum shock shaft velocity in the compression and rebound strokes for the full suspension stroke specified by the maximum stroke position of the link ratio curve inputs. ReStackor also records the maximum shock shaft stroke velocity occurring for the requested stroke depth specified by the "Max Stroke" input parameter. 

Maximum shock shaft stroke velocities

Comp.max [=] Maximum shock shaft compression velocity for a full stroke specified by the limits of the input link ratio curve. The first line specifies maximum velocities for the wheel bottoming stroke and the second line specifies the limit of the chassis bottoming stroke

C.comp [=] Shock compression damping coefficient at the maximum shaft velocity

Rbnd.max [=] Maximum shock shaft rebound velocity for a full stroke specified by the limits of the input link ratio curve. The first line specifies the maximum velocity occurring in the rebound stroke after wheel bottoming and the second line specifies the maximum rebound velocity after chassis bottoming

C.rbnd [=] Shock rebound damping coefficient at the maximum shaft velocity

U.whl [=] Maximum rebound stroke suspension wheel velocity for the stroke depth specified by the "Max Stroke" input parameter. First line give the maximum velocity during the wheel response stroke and the second line gives the chassis stroke

Damp Ratio [=] Rebound/compression damping ratio at each U.whl rebound velocity

Suspension link ratio

The final output block lists the wheel and shock position input data used to determine the suspension link ratio along with the link ratio and travel ratio determined from the input values. Input data points that are more than 5% off of the average curve are listed in the y.bad output column and plotted as green data symbols on the link ratio plot.

y.wheel [=] Wheel position measured from full extension

y.shock [=] Shock position measured from full extension

y.input [=] Shock position input value

y.bad [=] y.input values that are more than 5% off of the average link ratio curve

LR [=] Suspension link ratio defined as the incremental change in shock position for an incremental change in wheel position

1/TR [=] Suspension travel ratio defined as the suspension wheel position divided by the shock position. Outputs are 1/TR for plotting purposes.