# Shape Control for Experimental Continuation -- description of raw data

## Description of .lvm (LabView) data files. No special software apart from a text editor is required to open the .lvm. They are .csv readable.

### File names
Files are named with the following code: "T.TTmm_SS_C_R.lvm", where:
    T.TT = nominal arch thickness (1.75 for all arches in this work)
    SS = specimen number
    C = test configuration (M = midpoint scan; P = probe scan)
    R = run number

Not all runs are included; some runs resulted in specimen breakages or other anomalies, and were discarded. The data files provided here are the same set as used for the calculations in the paper. 

### File type
The raw test data are stored in .LVM files; the format used by LabView for data storage. LVM files can be opened in any text editor, and are formatted identically to Comma Separated Value (CSV) files. The data begin on line 24, after the header. 

### Channels
There are 5 columns, corresponding to the following data series: 
    1 - time (s)
    2 - linear transducer position (mm)
    3 - Instron load (N)
    4 - Instron position (mm)
    5 - Load cell load (N)

"Instron" refers to the test machine used. Channels 2 and 5 refer to the additional force and displacement measurements used in the probe scans. 

Depending on the type of test, these channels correspond to different control points on the arch: 

Midpoint scans: 
    linear transducer position (mm)     = not connected to arch
    Instron load (N)                    = midpoint force
    Instron position (mm)               = midpoint displacement
    Load cell load (N)                  = not connected to arch 

Probe scans: 
    linear transducer position (mm)     = midpoint displacement
    Instron load (N)                    = probe force
    Instron position (mm)               = probe displacement
    Load cell load (N)                  = midpoint force

All forces (and displacements) are treated as positive downwards in this work. For the Instron measurements, positive force corresponds to compression. For the other load cell (used in the probe scans only), positive force corresponds to tension. The user may need to flip (multiply by -1) the data series to obtain the correct sign measurements. 

## Probe scan delta_m offset calculation

In the probe scans, the arch midpoint is fixed using a moveable platform, whose height is controlled using four threaded rods. Stepped blocks are placed under the platform to quickly and repeatably obtain the same delta_m increments across all arch specimens (see "stepped_blocks.png"). The steps are numbered, and the numbers are read upwards to the flat surface directly above. The midpoint platform is fixed on the top step (step 0) to zero the linear transducer reading; this provides the same delta_m reference point for all specimens. Step 1 is used as the delta_m location for the first probe scan. However, both points are arbitrary locations and must be related to the resting position of the arch (true delta_m=0) in order to plot the probe scan data correctly. "measuring_offset.png" shows the starting frames of a midpoint scan and the first probe scan (step 1) superimposed. The difference in midpoint height is measured in pixels, and converted to 8mm using the ruler included in the frame (the image has been cropped and rearranged). The offset between the linear transducer zero position and the arch true delta_m zero position is obtained by the calculation in "stepped_blocks_explained.png". To obtain the correct delta_m readings for the probe scan data, the user must subtract 4.09 mm from the Instron position readings.

Robin Neville & Rainer Groh 14/05/2018