1GMTFLEXURE(1) GMT GMTFLEXURE(1)
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6 gmtflexure - Compute flexural deformation of 2-D loads, forces, bending
7 and moments
8
10 gmtflexure -Drm/rl[/ri]/rw -ETe[u]|D|file [ -A[l|r][/args] ] [
11 -CpPoisson ] [ -CyYoung ] [ -Fforce ] [ -Qargs] [ -S ] [ -Twfile]
12 [ -V[level] ] [ -Wwd] [ -Zzm] [ -bibinary ] [ -dnodata ] [ -eregexp
13 ] [ -hheaders ] [ -iflags ] [ -oflags ]
14 Note: No space is allowed between the option flag and the associated
16 arguments.
17
19 gmtflexure computes the flexural response to 2-D loads using a range of
20 user-selectable options, such as boundary conditions, pre-existing
21 deformations, variable rigidity and restoring force, and more. The
22 solutions are obtained using finite difference approximations to the
23 differential equations.
24
26 -Drm/rl[/ri]/rw
27 Sets density for mantle, load, infill (optionally, otherwise it
28 is assumed to equal the load density), and water. If ri is not
29 given then it defaults to rl.
30 -ETe[u]|D|file
32 Sets the elastic plate thickness (in meter); append k for km.
33 If the elastic thickness exceeds 1e10 it will be interpreted as
34 a flexural rigidity D instead (by default D is computed from Te,
35 Young's modulus, and Poisson's ratio; see -C to change these
36 values). Alternatively, supply a file with variable plate
37 thicknesses or rigidities. The file must be co-registered with
38 any file given via -Q.
39
41 -A[l|r]bc[/args]
42 Sets the boundary conditions at the left and right boundary.
43 The bc can be one of four codes: 0 selects the infinity condi‐
44 tion, were both the deflection and its slope are set to zero. 1
45 selects the periodic condition where both the first and third
46 derivatives of the deflection are set to zero. 2 selects the
47 clamped condition where args (if given) sets the deflection
48 value [0] (and its first derivative is set to zero), while 3
49 selects the free condition where args is given as moment/force
50 which specify the end bending moment and vertical shear force
51 [0/0]. Use SI units for any optional arguments.
52 -CpPoisson
54 Change the current value of Poisson's ratio [0.25].
55 -CyYoung
57 Change the current value of Young's modulus [7.0e10 N/m^2].
58 -Fforce]
60 Set a constant horizontal in-plane force, in Pa m [0]
61 -Qn|q|t[args]
63 Sets the vertical load specification. Choose among these three
64 options: -Qn means there is no input load file and that any
65 deformation is simply driven by the boundary conditions set via
66 -A. If no rigidity or elastic thickness file is given via -E
67 then you must also append min/max/inc to initiate the locations
68 used for the calculations. Append + to inc to indicate the num‐
69 ber of points instead. -Qq[loadfile] is a file (or stdin if not
70 given) with (x,load in Pa) for all equidistant data locations.
71 Finally, -Qt[topofile] is a file (or stdin if not given) with
72 (x,load in m or km, positive up); see -M for topography unit
73 used [m].
74 -S Compute the curvature along with the deflections and report them
76 via the third output column [none].
77 -Twfile
79 Supply a file with pre-existing deformations [undeformed sur‐
80 face].
81 -Wwd Specify water depth in m; append k for km. Must be positive
83 [0]. Any subaerial topography will be scaled via the densities
84 set in -D to compensate for the larger density contrast with
85 air.
86 -Zzm Specify reference depth to flexed surface in m; append k for km.
88 Must be positive [0]. We add this value to the flexed surface
89 before output.
90 -V[level] (more ...)
92 Select verbosity level [c].
93 -bi[ncols][t] (more ...)
95 Select native binary input.
96 -d[i|o]nodata (more ...)
98 Replace input columns that equal nodata with NaN and do the
99 reverse on output.
100 -e[~]"pattern" | -e[~]/regexp/[i] (more ...)
102 Only accept data records that match the given pattern.
103 -h[i|o][n][+c][+d][+rremark][+rtitle] (more ...)
105 Skip or produce header record(s).
106 -icols[+l][+sscale][+ooffset][,...] (more ...)
108 Select input columns and transformations (0 is first column).
109 -ocols[,...] (more ...)
111 Select output columns (0 is first column).
112 -^ or just -
114 Print a short message about the syntax of the command, then
115 exits (NOTE: on Windows just use -).
116 -+ or just +
118 Print an extensive usage (help) message, including the explana‐
119 tion of any module-specific option (but not the GMT common
120 options), then exits.
121 -? or no arguments
123 Print a complete usage (help) message, including the explanation
124 of all options, then exits.
125
127 The -M option controls the units used in all input and output files.
128 However, this option does not control values given on the command line
129 to the -E, -W, and -Z options. These are assumed to be in meters
130 unless an optional k for km is appended.
131
133 We solve for plate flexure using a finite difference approach. This
134 method can accommodate situations such as variable rigidity, restoring
135 force that depends on the deflection being positive or negative,
136 pre-existing deformation, and different boundary conditions.
137
139 To compute elastic plate flexure from the topography load in topo.txt,
140 for a 10 km thick plate with typical densities, try
141 gmt flexure -Qttopo.txt -E10k -D2700/3300/1035 > flex.txt
143
146 gmt, gravfft, grdflexure, grdmath
147
149 2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
1505.4.5 Feb 24, 2019 GMTFLEXURE(1)