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Механики XXI веку. № 15 2016 г.
430
To assess the degree of influence of thermal effects on the shift in the freezing of the soil in the cal-
culation of the friction force with the adhesion negative temperature derating factor determined forces freez-
ing
. .
. .
.
б в
т в
в
k
. The levels and ranges of variation factors during thermal exposure basis determined
on a priori information and analysis are presented in Table 1.
Options equipment to create thermal effects (their rational values) were selected on the basis of pre-
liminary experiments and studies based objective function (shear stress) on the parameters of thermal effects
in the course of the experiments did not change: the heating temperature of the radiating surface 85°C, expo-
sure time 15 seconds.
Table 1
The levels and ranges of variation factors
Levels factors
interval
Factors
-2
-1
0
1
2
X1–dispersion
ground, Dэ, mm
9·10
-3
7·10
-3
5·10
-3
3·10
-3
1·10
-3
2·10
-3
X2 – normal ground
pressure P, kPa
0
10
20
30
40
10
X3 – soil moisture,
W,%
7,5
12,5
17,5
22,5
27,5
5,0
X4 – ambient tem-
perature, Т,
С
5
-5
-15
-25
-35
10
X5 – the contact
time, t, minutes
0,5
10,5
20,5
30,5
40,5
10
As a result of the matrix design of experiments by varying the main factors contributing to
soil adhesion to the metal surface of the working body at temperatures below freezing, and process-
ing of the values of the coefficients of efficiency of the thermal effects of using the software pack-
age STATISTICA, obtained the following regression dependence:
During thermal exposure in coded form:
;5 4
0071 ,0 5 3
0096 ,0 4 3
0268 ,0 5 2
0027 ,0
4 1
0099 ,0 31
0041 ,0 2
5
0031 ,0 2
4
0164 ,0 2
2
0087 ,0 2
1
0114 ,0
5
0235 ,0 4 040 ,0 3
0349 ,0 2
0105 ,0 1
0155 ,0
9178 ,0 .
XX
XX
XX
XX
XX
XX
X
X
X
X
X
X
X
X
X
эфk
- During thermal exposure in kind
;
5 101,7 4 10 92,1 4 10 36,5
5 107,2 3 106,2
5 104,7
3 10 285
3 10 509
3 10 410 25 101,3 2 5 104,16 2 5 107,8 2 310 85,2 3 10 50,9
3
10 97,12
2
10 55,1
3
10 01,6
35,27
497 ,0 .
tT
Wt
WT
tP
PT
PW
DT
DT
WD
t
T
p
D
t
T
W
p
D
эфk
During thermal exposure in coded form
;54 52,153 11,143 54,032 90,042 57,132 15,251 22,2
41 85,231 40,021 59,02
5 36,02
4 03,12
3 90,02
2 71,3
2
1 83,0 5 70,3 4 09,4 3 49,4 2 74,3 1 63,2 69,12 ..
XX
XX
XX
XX
XX
XX
XX
XX
XX
XX
X
X
X
X
X
X
X
X
X
X
втk
During thermal exposure in kind