CN102967498A - Low-gravity simulated lunar soil - Google Patents

Abstract

The invention belongs to the technical field of configuration of simulated lunar soil and particularly relates to low-gravity simulated lunar soil. The mechanical properties of the low-gravity simulated lunar soil can reach lunar soil in-situ mechanical properties as follows under the earth gravity of 1g: the pressure-bearing coefficient Kc is 0.14 N/cm<2> and kphi is 0.82 N/cm<3> and n is 1; the shearing coefficient C is 0.017 N/cm<2> and phi is 35 degrees and j is 1.8 cm; the physical density is 1/6 of the average density of the lunar soil, namely the density is 0.35 g/cc; and then, the simulated lunar soil is obtained by milling, sieving and grading grain diameters. The low-gravity simulated lunar soil can realize the full-simulation of the mechanical property of a lunar surface under the condition of ground gravity, and a manner of parabolic flight of an airplane does not need to be adopted to carry out a performance estimation test; and the test state is stable, the expenditure can be greatly saved and the low-gravity simulated lunar soil has the actual meaning of improving the effectiveness of a test check.

Description

A kind of low gravity simulation lunar soil

Technical field

The invention belongs to the configuring technical field of simulative lunar soil, be specifically related to a kind of low gravity simulation lunar soil.

Background technology

External simulative lunar soil has JSC-1, MLS-1, the MLS-2 of the U.S., the MKS-1 of Japan, and FJK-1, the high titanium lunar maria lunar soil of Apollo11 lunar landing point, low titanium lunar maria lunar soil and the highland lunar soil of Apollo14 lunar landing point are mainly simulated by Russia etc.Domestic aspect, patent of invention " a kind of preparation method of simulative lunar soil (CN 101957280A) ", proposed by astronomical observatory of the Chinese Academy of Sciences, and prepared the CAS-1 simulative lunar soil, its main secondary element forms similar to the chemical composition of Apollo14 lunar landing point lunar soil sample.Patent of invention " material of simulative lunar soil (CN 102115321A) " is proposed by Beijing Satellite Environment Engineering Research Institute, and it has disposed a kind of angle of friction is 40 ° simulative lunar soil, is used for the inspection tour prober for moon surface test.In addition, the bionical major test of Jilin University's engineering chamber, space flight and aviation university in Beijing had all once carried out the correlative study work of simulative lunar soil.

Above-mentioned simulative lunar soil focuses on that the physical property of lunar soil is simulated entirely, comprises the aspects such as density, size grading, mineral composition, water cut, particle shape.But according to research, lunar surface 1/6g gravity condition will produce obviously impact for the mechanical property of soil: the simulative lunar soil of the full simulation of physical property, its mechanical property is far above the lunar surface in-situ mechanical.For this reason, the external large aircraft that usually adopts loads corresponding testing equipment, carries out the low gravity state of parabolic flight simulation, thereby carries out the mechanical property evaluation test, and its shortcoming is that cost is huge, and the single test time is short.

Based on this, develop a kind of can be used under the 1g gravity condition, and the simulative lunar soil that its mechanical performance index reaches lunar surface mechanical property requirements in place fully is very important.

Summary of the invention

The object of the present invention is to provide the low gravity simulation lunar soil under a kind of 1g gravity condition, the mechanical property of this material reaches the lunar surface in-situ mechanical, can be used for carrying out result of performance test in the lunar surface tour device test internal field.

Simulative lunar soil provided by the invention, adopting the dry powder soil of Suburb of Shijiazhuang is primary raw material, and a small amount of Irish touchstone of proportioning is used for adjusting density, makes it under 1g ground gravity condition, and phsyical density is 1/6 of lunar soil average density, and namely density is 0.35g/cc; Then, mix by grinding, screening and size grading;

Above-mentioned simulative lunar soil, mechanical property are the lunar surface in-situ mechanical, i.e. the pressure-bearing COEFFICIENT K _cBe 0.14N/cm ²,

Be 0.82N/cm ³, n is 1; Shearing factor C is 0.017N/cm ²,

Be 35 °, j is 1.8cm;

The low gravity simulation lunar soil that the present invention proposes, can be implemented under the ground gravity condition lunar surface mechanical property simulates entirely, need not to adopt the mode of aircraft parabolic flight to carry out the Performance Evaluation test, trystate is stable, can significantly cut down expenses, have practical significance for the validity that improves the test examination.

Description of drawings

[Fig. 1] hangs down gravity simulation lunar soil proportioning process

The size grading curve of [Fig. 2] 4 kinds of candidate materials

[Fig. 3] Bei Shi presses in the dish test and adopts three groups of prototype pressing plates

The pressure-bearing characteristic one of [Fig. 4] candidate materials

The pressure-bearing characteristic two of [Fig. 5] candidate materials

The angle of internal friction of [Fig. 6] candidate materials and cohesion test result

The modulus of shearing test result of [Fig. 7] candidate materials

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail, with reference to Fig. 1,

The method specifically may further comprise the steps:

Step 1: the application model similarity theory is determined the configuration target;

For under earth 1g gravity state, the mechanical property characteristic of the simulation moon 1/6 low gravity simulation lunar soil at first needs to determine lunar soil equivalent configuration target.

When lunar rover carries out the hauling ability test at simulative lunar soil, moon 1/6g gravity environment and earth 1g gravity environment are carried out the analysis of similarity theory and model test, the π item that can get the effect of moon wheel earth is as follows:

${\mathrm{\&pi;}}_1=\frac{M}{{\mathrm{cLTm}}^2}$ ${\mathrm{\&pi;}}_2=\frac{{\mathrm{\&rho;L}}^3}{M}$ ${\mathrm{\&pi;}}_3=\frac{L}{{\mathrm{vTm}}^2}$ ${\mathrm{\&pi;}}_4=\frac{L}{{\mathrm{gTm}}^2}$ ${\mathrm{\&pi;}}_5=\frac{\mathrm{LM}}{{\mathrm{DPTm}}^2}$

Take test condition as the experimental prototype that adopts full-scale and 1/6 quality as constraint, then can get size, quality and acceleration of gravity constraint condition.Simultaneously, in order to guarantee under two kinds of gravity conditions that the mechanical performance index of soil (cohesion, angle of internal friction) is constant, then:

The cohesion proportional: $K_c=\frac{M_p}{M_m}\&CenterDot;\frac{L_m}{L_p}\&CenterDot;\frac{{{\mathrm{Tm}}_m}^2}{{{\mathrm{Tm}}_p}^2}=1$

The angle of internal friction proportional:

According to the π item, be met above-mentioned all conditions unique solution, namely the density proportional is:

$\frac{{\mathrm{\&rho;}}_p{L_p}^3}{M_p}=\frac{{\mathrm{\&rho;}}_m{L_m}^3}{M_m}\&DoubleRightArrow;K_p=\frac{{\mathrm{\&rho;}}_p}{{\mathrm{\&rho;}}_m}=\frac{{L_m}^3}{{{\mathrm{<figure-callout\; id="3"\; label="L\; p"\; filenames="HSA00000820738900012.png"\; state="\{\{state\}\}">L</figure-callout>}}_p}^3}\&CenterDot;\frac{M_p}{M_m}=1\&CenterDot;6=6$

The following formula explanation, under surface condition, the model test condition then satisfies the simulative lunar soil that mechanical property is simulated requirement entirely for adopting the experimental prototype of full-scale and 1/6 quality, and its necessary condition is that density is 1/6 of lunar soil density.

Simultaneously other proportional explanation, vehicle mass need to be by suspension method with weight reducing to 1/6, and speed need be reduced to

Doubly.

Step 2: determine the simulative lunar soil main material by particle diameter and unit weight test;

Select the dry powder soil of multiple different regions as the basic material of configuration simulative lunar soil, approximate with the material of lunar maria volcano Irish touchstone origin, its density is 0.35g/cc close to density expectation value in the step 1, and expectation value unit weight mean deviation is not more than 10%;

Simultaneously, the grain size of lunar soil and particle diameter distribute, and are to determine one of the physics of lunar soil and major parameter of mechanical property.The particle of lunar soil is tiny, diameter take less than 1mm as main, most particle diameters between 30 μ m～1mm, median particle diameter between 40 μ m～130 μ m, average out to 70 μ m.

For this reason, select 2 kinds of riverbed, Yongding, Beijing to do husky (numbering S-1, S-2), and the dry powder of Suburb of Shijiazhuang (S-3, S-4) carry out the test of unit weight and particle diameter distribution;

Unit weight adopts the weight method test, and it is worth referring to table 1.Wherein the compressibility of S-1, S-2 is not strong, adopts tipped fill or stir resulting unit weight to change not quite, and its average is respectively 1.4g/cm3 and 1.37/cm3; Adopt S-3, S-4 to show obvious compressibility, adopt the method for vibration, its unit weight changes very obvious.

Median particle diameter (μ m) and the unit weight (g/cm of table 1SNJ series analog lunar soil ³)

?	SNJ-1	SNJ-2	SNJ-3	SNJ-4
					d50	75	118	＜50	81
γ(g/cm 3)	1.37	1.4	0.32	0.38

Adopt the sieve shaker method that four kinds of materials are carried out granularmetric analysis, test result as shown in Figure 2.As seen from the figure, the size grading of S-1, S-4 simulative lunar soil is close, meets the lunar soil particle diameter regularity of distribution.S-2 belongs to the lunar soil lower size, and particle is thicker; SNJ-3 has surpassed the lunar soil upper size, and particle is superfine.The median particle diameter of four kinds of simulative lunar soils is referring to table 1.

From the angle of configuration, the unit weight of candidate materials and particle diameter are all satisfactory, are the S-4 materials, are a kind of dry powder soil that is positioned at Suburb of Shijiazhuang, and its phsyical density is 0.38; Median particle diameter is 81 μ m after grinding.

Step 3: press dish method testing soil pressure-bearing characteristic parameter by Bei Shi, and utilization participates in the adjustment that Irish touchstone carries out mechanical property;

Main 3 parameter indexs of test analysis simulative lunar soil under the wheel normal force comprise: deformation index n, cohesiveness deformation modulus kc, friction texturizing modulus k φ.It is non-standard test that Bei Shi presses the dish method, and three groups of circular Bei Shi plates are adopted in this test, and its diameter is respectively 7.6cm, 10.2cm, and 13cm, as shown in Figure 3.

On ergograph, rotate handle the Bei Shi plate is descended, every decline 2mm reads corresponding power value on the electronic scales; Swing handle makes Bei Shi plate continuous decrease, until reach the maximum range (250kg) of electronic scale.Process of the test needs to finish rapidly at short notice, and the power of swing handle will continue to strengthen, and can not fluctuate back and forth.

The S-4 candidate materials can find that by the pressure-bearing test two kinds of situations are arranged usually in the different acquisition place, and a kind of is to be higher than lunar soil pressure-bearing mechanical property, referring to Fig. 4; Another is the load performance that is lower than lunar soil, referring to Fig. 5.

At this moment, in the situation that is higher than lunar soil pressure-bearing mechanical property, attempt adopting vibratory drilling method, reduce the factor of porosity of candidate materials, test again, if still be higher than lunar soil pressure-bearing mechanical property, then be considered as invalid sample, again according to step 2, gather pedotheque;

Be lower than the situation of lunar soil mechanical property when generation pressure-bearing mechanical property, then attempt trace and mix the Irish touchstone of pulverizing, be not higher than 0.25% of gross sample amount at every turn, after mixing by vibration, again carry out step 3, until the simulative lunar soil mechanical property of proportioning reaches desired value.

Experimental test shows that the sample that gathers has same mechanical attribute in the 1km scope, larger distance then needs again the proportioning situation of sample to be demarcated, in this example, the simulative lunar soil of final configuration, its Irish touchstone is 0.5% of sample total amount;

Step 4: by shear test method testing soil shear property parameter;

Main 3 parameter indexs of test analysis simulative lunar soil under the wheel tangential forces comprise: angle of internal friction

Cohesion force C, detrusion modulus j0., by " Standard for test methods of earthworks " (GB/T 50123-1999), adopt direct shear test to measure the shearing strength of simulative lunar soil material.

The S-4 candidate materials is by the material after the Irish touchstone proportioning, by direct shear test, also will there will be two kinds of situations, and the one, angle of internal friction is lower than below 25 °, and another is to be higher than 25 °.

For the first situation, namely angle of internal friction is lower than below 25 °, needs the particle shape by the electron microscope observation material, determines whether it is effective.This is because the particle shape of true lunar soil has from the sphere to the angular, and is relative common with the particle shape of strip, subangular and angular.The polygon particle shape is so that produce easily interlocking between month soil particle, the difficulty of mutually sliding, and this causes the menology lunar soil to have larger resistibility at the opposing foreign object aspect being inserted into, and it is higher that mechanical behavior shows as angle of internal friction.By electron microscope observation, if particle shape is spherical, then need to reselect the configuration material, according to the process in the step 2, restart the configuration of simulative lunar soil.

For the second situation, the mechanical property that then is judged to be this kind simulative lunar soil is effective, disposes in this example the angle of internal friction of sample and cohesion test result referring to Fig. 6; The modulus of shearing test result is referring to Fig. 7.

Claims (1)

1. one kind low gravity simulation lunar soil, it is characterized in that: described low gravity simulation lunar soil mechanical characteristic is: under the 1g terrestrial gravitation, can reach the lunar soil in-situ mechanical, the pressure-bearing COEFFICIENT K _cBe 0.14N/cm ²,

Be 0.82N/cm ³, n is 1; Shearing factor C is 0.017N/cm ²,

Be 35 °, j is 1.8cm, and phsyical density is 1/6 of lunar soil average density, and namely density is 0.35g/cc; Then by grinding, screening, size grading, thereby obtain a kind of simulative lunar soil.

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