CN104330298A - Method and device for evaluating and measuring mesomechanics/micromechanics performance of surface gradient metal material - Google Patents

Abstract

The invention discloses a method and a device for evaluating and measuring the mesomechanics/micromechanics performance of a surface gradient metal material. The method comprises the following steps: establishing a finite element model for a nano-indentation test, and identifying the reliability of the model; evaluating the mesomechanics performance parameters of the surface gradient material based on a surface treatment process and a base material elastic modulus, and calculating the corresponding micromechanics performance parameters of the surface gradient material by virtue of the finite element model; performing dimensional analysis on an applied load and indentation contact depth based on a mathematical modeling method, and establishing a dimensionless equation; selecting the corresponding mesomechanics/micromechanics performance parameters which are evaluated and calculated according to the dimensionless equation, and establishing a dimensionless function relational expression; performing the nano-indentation test along different depth directions on the surface of a sample to obtain a load-displacement response curve, and reversing the mesomechanics performance parameters of the corresponding position of the material; establishing a mesomechanics performance gradient curve of the surface gradient material based on the determined mesomechanics performance parameters.

Description

The thin Micro Mechanical Properties assessment measuring method of surface graded metal material and device

Technical field

The invention relates to metal material mechanics Performance Testing Technology, particularly about a kind of thin Micro Mechanical Properties assessment measuring method and device of surface graded metal material.

Background technology

Along with the development of the high-precision end of industry, microminiature machinery or component are by a large amount of development and use.Meanwhile, have the requirement such as high strength, high reliability for meeting mechanism, the novel surface processing technologies such as pulsed discharge, ion implantation, laser-impact and Carburization Treatment technique are also widely adopted.Therefore, clearly comprise the fundamental mechanics performance of the construction material of processing layer, seem particularly important.

The mechanical property of traditional metal materials is obtained by the monotonic tension test of standard specimen.Corresponding surface-treated material, there is two problems in its mechanical property measurement: (1) ignores the existence of processing layer, processing layer and matrix is considered as homogeneous material to process, do not take into account the graded of material surface performance.(2) for microminiature structure, its testing equipment and measuring method are all inapplicable.Nano-hardness tester may be used for the mensuration of material in micro/nano level mechanical property, but current research mainly concentrates on membraneous material, and surface-treated metal material is only laid particular emphasis on to the test of hardness, do not form a kind of effective, material gradient mechanical property characterizing method of comprising processing layer so far.

Therefore, a kind of there is better theoretical property, the thin Micro Mechanical Properties appraisal procedure of practical reliable, succinct surface graded metal material easily urgently sets up.

Summary of the invention

The invention provides a kind of thin Micro Mechanical Properties assessment measuring method and device of surface graded metal material, the error that approximate test material mechanical performance brings to avoid ignoring surface-treated layer, makes up the blank of surface graded mechanical property characterizing method.

To achieve these goals, the invention provides a kind of thin Micro Mechanical Properties assessment measuring method of surface graded metal material, described thin Micro Mechanical Properties assessment measuring method comprises:

Step 1: by two-dimentional modeling, give material properties, stress and strain model, applying boundary condition etc., set up the limit element artificial module of nano indentation test, and verify its accuracy;

Step 2: based on process of surface treatment and matrix material elastic modulus, estimates micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with described in finite element model calculate described micro-mechanical property parameter corresponding Micro Mechanical Properties parameter (F, S, h _c); Wherein, E for measure and monitor the growth of standing timber material elastic modulus, σ _yfor measure and monitor the growth of standing timber material yield stress, n for measure and monitor the growth of standing timber material strain hardening exponent, F is the loaded load on nano indentation test compressing head, S for measure and monitor the growth of standing timber material hardness, h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth;

Step 3: based on mathematics modeling, to loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _ccarry out dimensional analysis, setting up measures and monitor the growth of standing timber about pressure head and institute expects the Non-di-mensional equation of correlation parameter:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

Step 4: according to Non-di-mensional equation, the trickle sight mechanics parameter of corresponding material (E, σ of estimating in integrating step 2 and calculating _y, n, F, S, h _c), set up dimensionless functional relation:

${\mathrm{\Π}}_{\mathrm{\α}}(\frac{{\mathrm{\σ}}_y}{E},n)=(a-\mathrm{bn}){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[c\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-\mathrm{dn}]}---\left(3\right)$

${\mathrm{\Π}}_{\mathrm{\β}}(\frac{{\mathrm{\σ}}_y}{E},n)=e+\mathrm{fexp}\left(\mathrm{gn}\right)\exp \left[i\left(\frac{{\mathrm{\σ}}_y}{E}\right)\right]---\left(4\right)$

Wherein, a, b, c, d, e, f, g, i are fitting parameter;

Step 5: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that described specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and by described material hardness, maximum load load F and impression contact degree of depth h _cvalue be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

Step 6: by the micro-mechanical property parameter (E, the σ that obtain in step 5 _y, n) by plotted against depth, set up the micro-mechanical property gradient curve of surface graded material.

In one embodiment, in described step 1, set up the limit element artificial module of nano indentation test, comprising: adopt two dimensional model to carry out modeling to measured and monitored the growth of standing timber material, utilize one dimension line segment to carry out modeling to pressure head, generate the initial solid model of nano indentation test.In view of the axial symmetry of model, get the limit element artificial module that 1/2nd of described initial solid model sets up nano indentation test.

In one embodiment, described material parameter attribute comprises: σ _y=1187MPa, E=201GPa, ν=0.3, n=0.203.

In one embodiment, described step 2 comprises: based on process of surface treatment and matrix material elastic modulus, estimates micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with described in finite element model, generate some groups of load-displacement response curves, according to described load-displacement response curve, calculate some groups of corresponding Micromechanics parameter (F, S, h _c).

In one embodiment, described step 3 comprises:

Based on mathematics modeling, by pressure head loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _cbeing expressed as measures and monitor the growth of standing timber about pressure head and institute expects the function general equation of correlation parameter:

F＝F(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (5)

h _c＝h _c(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (6)

Wherein, ν for measure and monitor the growth of standing timber material Poisson ratio, E _iand ν _ibe respectively elastic modulus and the Poisson ratio of pressure head, the friction factor that μ is pressure head and institute's survey storeroom, θ is the half-angle angle of pressure head;

When not considering to be coupled between parameter, described function general equation is converted into dimensionless function:

$\frac{F}{{\mathrm{Eh}}^2}=F(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(7\right)$

$\frac{h_c}{{\mathrm{Eh}}^2}=h_c(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(8\right)$

Above-mentioned pressure head and institute measure and monitor the growth of standing timber expect parameter in, the dimension [h] only having the dimension of elastic modulus [E] and the degree of depth is independently, and other parameters all represent by the form of the exponent product of these two independent dimensions.

Omit the E in described dimensionless function _i, ν _iand μ, for the pressure head of a given angle θ, application Π theorem, dimensionless functional relation is reduced to described Non-di-mensional equation further:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

In one embodiment, described step 5 comprises: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

In one embodiment, described step 6 comprises: by the micro-mechanical property parameter that obtains in step 5 by plotted against depth, set up the micro-mechanical property gradient curve of surface graded material.

To achieve these goals, the invention provides a kind of thin Micro Mechanical Properties assessment and measurement mechanism of surface graded metal material, described thin Micro Mechanical Properties measuring method device comprises:

Unit set up by model, by two-dimentional modeling, gives material properties, stress and strain model, applying boundary condition etc., sets up the limit element artificial module of nano indentation test, and verify its accuracy;

Trickle sight mechanics parameter computing unit, based on process of surface treatment and matrix material elastic modulus, estimates micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with described in finite element model calculate described micro-mechanical property parameter corresponding Micro Mechanical Properties parameter (F, S, h _c); Wherein, E for measure and monitor the growth of standing timber material elastic modulus, σ _yfor measure and monitor the growth of standing timber material yield stress, n for measure and monitor the growth of standing timber material strain hardening exponent, F is the loaded load on nano indentation test compressing head, S for measure and monitor the growth of standing timber material hardness, h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth;

Non-di-mensional equation generation unit, based on mathematics modeling, to loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _ccarry out dimensional analysis, setting up measures and monitor the growth of standing timber about pressure head and institute expects the Non-di-mensional equation of correlation parameter:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

Dimensionless correlation generation unit, according to Non-di-mensional equation, in conjunction with trickle sight mechanics parameter (E, the σ of the corresponding material of trickle sight mechanics parameter computing unit _y, n, F, S, h _c), matching obtains dimensionless functional relation;

${\mathrm{\Π}}_{\mathrm{\α}}(\frac{{\mathrm{\σ}}_y}{E},n)=(a-\mathrm{bn}){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[c\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-\mathrm{dn}]}---\left(3\right)$

${\mathrm{\Π}}_{\mathrm{\β}}(\frac{{\mathrm{\σ}}_y}{E},n)=e+\mathrm{fexp}\left(\mathrm{gn}\right)\exp \left[i\left(\frac{{\mathrm{\σ}}_y}{E}\right)\right]---\left(4\right)$

Wherein, a, b, c, d, e, f, g, i are fitting parameter;

Mechanical property parameters generation unit, prepares surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that described specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and by described material hardness, maximum load load F and impression contact degree of depth h _cvalue be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

Mechanical performance gradient curved unit, the micro-mechanical property parameter obtained by mechanical property parameters generation unit, by plotted against depth, sets up the micro-mechanical property gradient curve of surface graded material.

In one embodiment, described model set up unit specifically for: adopt two dimensional model to carry out modeling to measured and monitored the growth of standing timber material, utilize one dimension line segment to carry out modeling to pressure head, generate the initial solid model of nano indentation test.In view of the axial symmetry of model, get described initial solid model 1/2nd set up limit element artificial module.

In one embodiment, described material parameter attribute comprises: σ _y=1187MPa, E=201GPa, ν=0.3, n=0.203.

In one embodiment, described trickle sight mechanics parameter computing unit specifically for: based on process of surface treatment and matrix material elastic modulus, estimate micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with described in finite element model, generate some groups of load-displacement response curves, obtain some groups of Micromechanics parameters (F, S, h _c).

In one embodiment, described Non-di-mensional equation generation unit comprises:

General equation generation module, based on mathematics modeling, by pressure head loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _cbeing expressed as measures and monitor the growth of standing timber about pressure head and institute expects the function general equation of correlation parameter:

F＝F(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (5)

h _c＝h _c(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (6)

Wherein, ν for measure and monitor the growth of standing timber material Poisson ratio, E _iand ν _ibe respectively elastic modulus and the Poisson ratio of pressure head, the friction factor that μ is pressure head and institute's survey storeroom, θ is the half-angle angle of pressure head;

Dimensionless function generation module, for when not considering to be coupled between parameter, is converted into dimensionless function by described function general equation:

$\frac{F}{{\mathrm{Eh}}^2}=F(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(7\right)$

$\frac{h_c}{{\mathrm{Eh}}^2}=h_c(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(8\right)$

Above-mentioned pressure head and institute measure and monitor the growth of standing timber expect parameter in, the dimension [h] only having the dimension of elastic modulus [E] and the degree of depth is independently, and other parameters all represent by the form of the exponent product of these two independent dimensions.

Non-di-mensional equation generation module, for omitting the E in described dimensionless function _i, ν _iand μ, for the pressure head of a given angle θ, dimensionless functional relation is reduced to described Non-di-mensional equation by application Π theorem further:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

In one embodiment, mechanical property parameters generation unit specifically for: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, obtain a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _c, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position.

The present invention compensate for the blank of the thin Micro Mechanical Properties obtaining surface graded metal material in test determination and characterizing method.The present invention is based on the relation between the Micro Mechanical Properties of the surface graded material that dimensional method builds and micro-mechanical property, possess good theoretical foundation, for the fail-safe analysis and design studying surface graded metal material provides effective foundation; The invention provides a kind of characterizing method and measurement mechanism of thin Micro Mechanical Properties of surface graded metal material newly, the mechanical property change of surface graded metal material can be understood more intuitively.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the thin Micro Mechanical Properties measuring method process flow diagram of the surface graded metal material of the embodiment of the present invention;

Fig. 2 is embodiment of the present invention nano impress parameter schematic diagram;

Fig. 3 is embodiment of the present invention limited element calculation model figure;

Fig. 4 is the emulation of embodiment of the present invention Cr-Mn alloy steel nano impress and Experimental Comparison figure;

Fig. 5 is the structured flowchart of the trickle sight mechanical property measuring device of the surface graded metal material of the embodiment of the present invention;

Fig. 6 is the structured flowchart of the Non-di-mensional equation generation unit 503 of the embodiment of the present invention;

Fig. 7 is the test hardness distribution of the surface graded metal material of the embodiment of the present invention;

Fig. 8 is the yield strength matching gradient curve figure of the surface graded metal material of the embodiment of the present invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

As shown in Figure 1, the invention provides a kind of thin Micro Mechanical Properties assessment measuring method of surface graded metal material, described thin Micro Mechanical Properties measuring method comprises:

S101: by two-dimentional modeling, give material properties, stress and strain model, applying boundary condition etc., set up the limit element artificial module of nano indentation test, and verify its accuracy;

S102: based on process of surface treatment and matrix material elastic modulus, estimates surperficial functionally gradient material (FGM) micro-mechanical property parameter (E, σ _y, n), in conjunction with described in finite element model calculate its corresponding Micro Mechanical Properties parameter (F, S, h _c); Wherein, E for measure and monitor the growth of standing timber material elastic modulus, σ _yfor measure and monitor the growth of standing timber material yield stress, n for measure and monitor the growth of standing timber material strain hardening exponent, F is the loaded load on nano indentation test compressing head, S for measure and monitor the growth of standing timber material hardness, h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth;

S103: based on mathematics modeling, to loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _ccarry out dimensional analysis, setting up measures and monitor the growth of standing timber about pressure head and institute expects the Non-di-mensional equation of correlation parameter:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

S104: according to Non-di-mensional equation, chooses the trickle sight mechanics parameter of material corresponding in S102 (E, σ _y, n, F, S, h _c), matching obtains dimensionless functional relation:

${\mathrm{\Π}}_{\mathrm{\α}}(\frac{{\mathrm{\σ}}_y}{E},n)=(a-\mathrm{bn}){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[c\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-\mathrm{dn}]}---\left(3\right)$

${\mathrm{\Π}}_{\mathrm{\β}}(\frac{{\mathrm{\σ}}_y}{E},n)=e+\mathrm{fexp}\left(\mathrm{gn}\right)\exp \left[i\left(\frac{{\mathrm{\σ}}_y}{E}\right)\right]---\left(4\right)$

Wherein, a, b, c, d, e, f, g, i are fitting parameter;

S105: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

S106: by the micro-mechanical property parameter that obtains in S105 by plotted against depth, set up the micro-mechanical property gradient curve of surface graded material.

Flow process is as shown in Figure 1 known, and first the present invention sets up the limit element artificial module of nano indentation test, verifies; Then based on limit element artificial module, Micromechanics parameter is calculated according to mesomechanics material parameter; Based on mathematics modeling, contact degree of depth h in conjunction with loaded load F with impression _ccarry out dimensional analysis, set up Non-di-mensional equation; According to Non-di-mensional equation, choose corresponding some groups of material Micromechanical Parameters and the discrete values point corresponding to some groups of Micromechanics parameters, matching obtains dimensionless functional relation; Prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, a series of load-displacement response curve is obtained by predetermined depth, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position; Finally, by the micro-mechanical property parameter that obtains in above-mentioned by plotted against depth, the micro-mechanical property gradient curve of its material is set up.

The above-mentioned flow process of Fig. 1 may be summarized to be that simulation calculation, parameter fitting, indentation test and model are counter pushes away four steps, by method as shown in Figure 1, the present invention compensate for the blank of the thin Micro Mechanical Properties obtaining surface graded metal material in test determination and characterizing method.The present invention is based on the relation between the Micro Mechanical Properties of the surface graded material that dimensional method builds and micro-mechanical property, possess good theoretical foundation, for the fail-safe analysis and design studying surface graded metal material provides effective foundation; The invention provides a kind of characterizing method and measurement mechanism of thin Micro Mechanical Properties of surface graded metal material newly, the mechanical property change of surface graded metal material can be understood more intuitively.

The present invention adopts Nanoindentation to carry out modeling, Nanoindentation also claims the degree of depth responsive indentation, be one of method of the simplest test material Micro Mechanical Properties, the various mechanical properties of material can be measured on nanoscale, as load-displacement curves, elastic modulus, hardness etc.Nano indentation test meaning of parameters as shown in Figure 2, the present invention is based on ABAQUS and sets up nano impress limit element artificial module.In Fig. 2, h and h _rbe respectively depth of cup and remaining depth of cup, h _cpressure head and the contact degree of depth of material when referring to pressure head press-in material, a is pressure head radius.

For real simulation nano indentation test measure institute measure and monitor the growth of standing timber expect Micromechanics parameter, in one embodiment, when the present invention sets up the limit element artificial module of nano indentation test in S101, first two dimensional model is adopted to carry out modeling to measured and monitored the growth of standing timber material, utilize one dimension line segment to carry out modeling to pressure head, generate the initial solid model of nano indentation test.In view of the axial symmetry of model, get the limit element artificial module that 1/2nd of described initial solid model sets up nano indentation test.Limit element artificial module can carry out simulation analysis, as shown in Figure 3 after setting up.

When S101 specifically implements, the size effect of nano impress will be considered in the process setting up limit element artificial module, the size of material of measuring and monitoring the growth of standing timber should be greater than more than ten times of depth of cup, in realistic model, depth of cup is 1500nm, measure and monitor the growth of standing timber material for the length of side be the square of 30 μm.In the region that distance pressure head is nearer, plastic yield is comparatively large, and grid cell is little and close, in the region that distance pressure head is far away, the distortion that material occurs is less, and the region even had only there occurs elastic deformation, plastic yield does not occur, its region adopts comparatively large and thin grid.Transitional region is adopted to connect between each region.In the nearer region of distance pressure head, grid cell size is 125nm, and unit adopts four node symmetries to reduce unit (CAX4R), so that can the large deformation that produces of its region of accurate simulation.With Cr-Mn alloy steel for object, its test findings and result of finite element more consistent, as shown in Figure 4.

In S101, material parameter attribute comprises: σ _y=1187MPa, E=201GPa, ν=0.3, n=0.203, above-mentioned value is only one embodiment of the present invention, and the present invention is not as restriction.

In one embodiment, in S101, border, load are respectively: border is fixed below, and pressure head moves down 1500nm.

S102, by emulating same models for several times, can obtain forces associated mathematic(al) parameter.During concrete enforcement, some groups of mesomechanics material parameters can be preset, as shown in table 1 below.

The material elastic-plastic mechanical parameter combination adopted during table 1 analog computation

Elastic modulus due to surveyed cemented metal material matrix is 201GPa, the 70 groups of parameter values choosing 170GPa and 210GPa adjacent with its elastic modulus in table 1 are input in the limit element artificial module created in S101, and then 70 groups of load-displacement response curves can be obtained, and calculate 70 groups of Micromechanics parameter (F, S, h _c).Thin sight elastoplastic mechanical parameters (E, σ _y, n) with Micromechanics parameter (F, S, h _c) between there is relation one to one.E for measure and monitor the growth of standing timber material elastic modulus; σ _yfor measure and monitor the growth of standing timber material yield stress; N for measure and monitor the growth of standing timber material strain hardening exponent; F is the loaded load on nano indentation test compressing head; S for measure and monitor the growth of standing timber material hardness; h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth.

S103 is by dimensional analysis, sets up the step of Non-di-mensional equation.During concrete enforcement, can utilize the thought of mathematical modeling by pressure head loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _cbeing expressed as measures and monitor the growth of standing timber about pressure head and institute expects the function general equation (functional relation) of correlation parameter:

F＝F(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (5)

h _c＝h _c(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (6)

In above-mentioned general equation, ν for measure and monitor the growth of standing timber material Poisson ratio, E _iand ν _ibe respectively elastic modulus and the Poisson ratio of pressure head, the friction factor that μ is pressure head and institute's survey storeroom, θ is the half-angle angle of pressure head.

Unit for variable each in above-mentioned equation is as shown in table 2 below, and by dimensional analysis, the dimension [h] of the dimension [E] and the degree of depth of choosing elastic modulus is basic dimension, and other parameters all represent by the form of the exponent product of these two independent dimensions.

The dimension of table 2 metal material impression problem associated arguments

Parameter	Symbol	Dimension
			Indentation load	F	LMT -2
Yield strength	σ y	L -1MT -2
			Strain hardening exponent	n	1
Elastic modulus	E	LMT -2
			The impression contact degree of depth	h c	L

When not considering to be coupled between parameters, above-mentioned general equation can be converted into following dimensionless function:

$\frac{F}{{\mathrm{Eh}}^2}=F(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(7\right)$

$\frac{h_c}{{\mathrm{Eh}}^2}=h_c(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(8\right)$

In above-mentioned dimensionless function, the distortion of pressure head is negligible, accordingly can pressure head parameter E in the above-mentioned dimensionless function of cancellation _iand ν _i, the impact of coefficientoffrictionμ on wide-angle pressure head press-in problem is very little, therefore also can cancellation by coefficientoffrictionμ in above-mentioned dimensionless function.For metal material, Poisson ratio ν can get 0.3, does cancellation process equally.So for the pressure head of a given angle θ, application Π theorem dimensionless functional relation is reduced to the Non-di-mensional equation in S103 further:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

S104 is the step of the expression determining dimensionless function.During concrete enforcement, on the basis of S102, S103, according to above-mentioned Non-di-mensional equation, corresponding 70 groups of material Micromechanical Parameters (E, σ can be chosen _y, n) He 70 groups of Micromechanics parameters (F, S, h _c) corresponding to discrete values point, fitting data obtains concrete dimensionless functional relation, sees above-mentioned formula (3) and formula (4).

In one embodiment, to the described carburizing gradient Cr-Mn alloy steel parts of trickle sight mechanical property parameters the unknown, in above-mentioned formula (3), (4), the value of parameter a, b, c, d, e, f, g, i is respectively: a=2.67, b=2.11, c=-0.053, d=0.42, e=0.5, f=0.29, g=-2.76, i=-40.32.Accordingly, formula (3) and (4) can be changed into:

$\frac{F}{{\mathrm{Eh}}^2}=(2.67-2.11n){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[-0.053\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-0.42n]}---\left(9\right)$

$\frac{h_c}{h}=0.5+0.29\exp (-2.76n)\exp [-40.32\left(\frac{{\mathrm{\σ}}_y}{E}\right)]---\left(10\right)$

Based on different surface treatment technique and matrix material elastic modulus, estimate surperficial functionally gradient material (FGM) micro-mechanical property parameter difference for some groups that choose, the value of above-mentioned fitting parameter is also different, repeats no longer one by one.

For the described carburizing gradient Cr-Mn alloy steel parts of trickle sight mechanical property parameters the unknown, when S105 specifically implements, first carburizing gradient parts Cross section polishing sample is prepared, then along the depth direction that specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _c, and being updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position, the distribution of Cr-Mn alloy steel (carburizing gradient parts) hardness is as shown in Figure 7.

By S106, by the micro-mechanical property parameter that obtains in step S105 by plotted against depth, set up surface graded material micro-mechanical property gradient curve.During concrete enforcement, for yield strength, obtain Cr-Mn alloy steel (carburizing gradient parts) yield strength matching gradient curve as shown in Figure 8.

The present invention compensate for the blank of the thin Micro Mechanical Properties quantizing surperficial graded metal material in test determination and characterizing method.The present invention is based on the relation between the Micro Mechanical Properties of the surface graded material that dimensional method builds and micro-mechanical property, possess good theoretical foundation, for the fail-safe analysis and design studying surface graded metal material supplies effective foundation; The invention provides a kind of characterizing method and measurement mechanism of thin Micro Mechanical Properties of surface graded metal material newly, the mechanical property change of surface graded metal material can be understood more intuitively.

As shown in Figure 5, the invention provides a kind of thin Micro Mechanical Properties assessment measurement mechanism of surface graded metal material, its thin Micro Mechanical Properties measuring method device comprises: unit 501 set up by model, trickle sight mechanics parameter computing unit 502, Non-di-mensional equation generation unit 503, dimensionless correlation generation unit 504 and mechanical property parameters generation unit 505.

Model sets up unit 501 for setting up the limit element artificial module of nano indentation test, carries out following simulation analysis: give material parameter attribute, carry out stress and strain model, applies boundary condition and load.

In one embodiment, 501 carry out modeling for adopting two dimensional model to measured and monitored the growth of standing timber material, utilize one dimension line segment to carry out modeling to pressure head, generate the initial solid model of nano indentation test.In view of the axial symmetry of model, get the limit element artificial module that 1/2nd of described initial solid model sets up nano indentation test.

The size effect of nano impress will be considered in the process setting up limit element artificial module, the size of material of measuring and monitoring the growth of standing timber should be greater than more than ten times of depth of cup, in realistic model, depth of cup is 1500nm, and institute measures and monitor the growth of standing timber and expects for the length of side is the square of 30 μm.In the region that distance pressure head is nearer, plastic yield is comparatively large, and grid cell is little and close, in the region that distance pressure head is far away, the distortion that material occurs is less, and the region even had only there occurs elastic deformation, plastic yield does not occur, its region adopts comparatively large and thin grid.Transitional region is adopted to connect between each region.In the region that distance pressure head is nearer, grid cell size is 125nm, and unit adopts four node symmetries to reduce unit (CAX4R), so that the large deformation that its region of accurate simulation produces.Adopt Cr-Mn alloy steel to verify limit element artificial module, result shows that its limit element artificial module is consistent with actual tests situation, as shown in Figure 4.

The material parameter attribute of above-mentioned imparting comprises: σ _y=1187MPa, E=201GPa, ν=0.3, n=0.203, above-mentioned value is only one embodiment of the present invention, and the present invention is not as restriction.

In one embodiment, the boundary condition of applying can be: border is fixed below; Load is that pressure head moves down 1500nm.

Trickle sight mechanics parameter computing unit 502 for based on described limit element artificial module, according to mesomechanics material parameter (E, σ _y, n) calculate Micromechanics parameter (F, S, h _c).

Based on process of surface treatment and matrix material elastic modulus, choose some groups of (E, σ in table 1 _y, n) parameter combinations is input in the limit element artificial module created in S101, thus can obtain some groups of load-displacement response curves, calculates some groups of Micromechanics parameters (F, S, h _c).Thin sight elastoplastic mechanical parameters (E, σ _y, n) with Micromechanics parameter (F, S, h _c) there is corresponding relation.E for measure and monitor the growth of standing timber material elastic modulus; σ _yfor measure and monitor the growth of standing timber material yield stress; N for measure and monitor the growth of standing timber material strain hardening exponent; F is the loaded load on nano indentation test compressing head; S for measure and monitor the growth of standing timber material hardness; h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth.

Non-di-mensional equation generation unit 503 for loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _ccarry out dimensional analysis, setting up measures and monitor the growth of standing timber about pressure head and institute expects the Non-di-mensional equation of correlation parameter:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

In one embodiment, as shown in Figure 6, Non-di-mensional equation generation unit 503 comprises: general equation generation module 601, dimensionless function generation module 602 and Non-di-mensional equation generation module 603.

General equation generation module 601 for, according to mathematics modeling, by pressure head loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _cbeing expressed as measures and monitor the growth of standing timber about pressure head and institute expects the function general equation of correlation parameter:

F＝F(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (5)

h _c＝h _c(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (6)

Wherein, ν for measure and monitor the growth of standing timber material Poisson ratio, E _iand ν _ibe respectively elastic modulus and the Poisson ratio of pressure head, the friction factor that μ is pressure head and institute's survey storeroom, θ is the half-angle angle of pressure head;

Described function general equation, for when not considering to be coupled between parameter, is converted into dimensionless function by dimensionless function generation module 602:

$\frac{F}{{\mathrm{Eh}}^2}=F(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(7\right)$

$\frac{h_c}{{\mathrm{Eh}}^2}=h_c(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(8\right)$

Above-mentioned pressure head and institute measure and monitor the growth of standing timber expect parameter in, the dimension [h] only having the dimension of elastic modulus [E] and the degree of depth is independently, and other parameters all represent by the form of the exponent product of these two independent dimensions.

Non-di-mensional equation generation module 603 is for omitting the E in described dimensionless function _i, ν _iand μ, for the pressure head of a given angle θ, dimensionless functional relation is reduced to Non-di-mensional equation by application Π theorem further, sees above-mentioned formula (1) and formula (2).

Dimensionless correlation generation unit 504, for according to described Non-di-mensional equation, chooses corresponding some groups of material Micromechanical Parameters (E, σ _y, n) with some groups of Micromechanics parameters (F, S, h _c) corresponding to discrete values point, fitting data obtains dimensionless functional relation:

${\mathrm{\Π}}_{\mathrm{\α}}(\frac{{\mathrm{\σ}}_y}{E},n)=(a-\mathrm{bn}){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[c\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-\mathrm{dn}]}---\left(3\right)$

${\mathrm{\Π}}_{\mathrm{\β}}(\frac{{\mathrm{\σ}}_y}{E},n)=e+\mathrm{fexp}\left(\mathrm{gn}\right)\exp \left[i\left(\frac{{\mathrm{\σ}}_y}{E}\right)\right]---\left(4\right)$

Wherein, a, b, c, d, e, f, g, i are fitting parameter.

Mechanical property parameters generation unit 505, for the preparation of surface graded material section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _c, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

In one embodiment, for the described carburizing gradient Cr-Mn alloy steel parts of trickle sight mechanical property parameters the unknown, the value of fitting parameter a, b, c, d, e, f, g, i in above-mentioned formula (3), (4) is respectively: a=2.67, b=2.11, c=-0.053, d=0.42, e=0.5, f=0.29, g=-2.76, i=-40.32.Now, formula (3) and formula (4) become:

$\frac{F}{{\mathrm{Eh}}^2}=(2.67-2.11n){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[-0.053\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-0.42n]}---\left(9\right)$

$\frac{h_c}{h}=0.5+0.29\exp (-2.76n)\exp [-40.32\left(\frac{{\mathrm{\σ}}_y}{E}\right)]---\left(10\right)$

Based on different surface treatment technique and matrix material elastic modulus, estimate surperficial functionally gradient material (FGM) micro-mechanical property parameter difference for some groups that choose, the value of above-mentioned fitting parameter is also different, repeats no longer one by one.

In one embodiment, mechanical property parameters generation unit 505 may be used for the described carburizing gradient Cr-Mn alloy steel parts for micro-mechanical property unknown parameters, first surperficial functionally gradient material (FGM) Cross section polishing sample is prepared, then along the depth direction that specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth.Obtain material hardness, maximum load load F and impression contact degree of depth h _c, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing carburizing functionally gradient material (FGM) relevant position;

In one embodiment, mechanical property parameters generation unit 506 by the micro-mechanical property parameter that obtains in unit 505 by plotted against depth, can set up surface graded material micro-mechanical property gradient curve.

The present invention compensate for the blank of the thin Micro Mechanical Properties obtaining surface graded metal material in test determination and characterizing method.The present invention is based on the relation between the Micro Mechanical Properties of the surface graded material that dimensional method builds and micro-mechanical property, possess good theoretical foundation, for the fail-safe analysis and design studying surface graded metal material supplies effective foundation; The invention provides a kind of characterizing method and measurement mechanism of thin Micro Mechanical Properties of surface graded metal material newly, the mechanical property change of surface graded metal material can be understood more intuitively.

Those skilled in the art should understand, embodiments of the invention can be provided as method, system or computer program.Therefore, the present invention can adopt the form of complete hardware embodiment, completely software implementation or the embodiment in conjunction with software and hardware aspect.And the present invention can adopt in one or more form wherein including the upper computer program implemented of computer-usable storage medium (including but not limited to magnetic disk memory, CD-ROM, optical memory etc.) of computer usable program code.

The present invention describes with reference to according to the process flow diagram of the method for the embodiment of the present invention, equipment (system) and computer program and/or block scheme.Should understand can by the combination of the flow process in each flow process in computer program instructions realization flow figure and/or block scheme and/or square frame and process flow diagram and/or block scheme and/or square frame.These computer program instructions can being provided to the processor of multi-purpose computer, special purpose computer, Embedded Processor or other programmable data processing device to produce a machine, making the instruction performed by the processor of computing machine or other programmable data processing device produce device for realizing the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.

These computer program instructions also can be stored in can in the computer-readable memory that works in a specific way of vectoring computer or other programmable data processing device, the instruction making to be stored in this computer-readable memory produces the manufacture comprising command device, and this command device realizes the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.

These computer program instructions also can be loaded in computing machine or other programmable data processing device, make on computing machine or other programmable devices, to perform sequence of operations step to produce computer implemented process, thus the instruction performed on computing machine or other programmable devices is provided for the step realizing the function of specifying in process flow diagram flow process or multiple flow process and/or block scheme square frame or multiple square frame.

Apply specific embodiment in the present invention to set forth principle of the present invention and embodiment, the explanation of above embodiment just understands method of the present invention and core concept thereof for helping; Meanwhile, for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.

Claims (10)

1. a thin Micro Mechanical Properties assessment measuring method for surface graded metal material, is characterized in that, comprising:

Step 1: by two-dimentional modeling, give material properties, stress and strain model, applying boundary condition, set up the limit element artificial module of nano indentation test, and verify the accuracy of described limit element artificial module;

Step 2: based on process of surface treatment and matrix material elastic modulus, estimates micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with described in finite element model calculate described micro-mechanical property parameter corresponding Micro Mechanical Properties parameter (F, S, h _c); Wherein, E for measure and monitor the growth of standing timber material elastic modulus, σ _yfor measure and monitor the growth of standing timber material yield stress, n for measure and monitor the growth of standing timber material strain hardening exponent, F is the loaded load on nano indentation test compressing head, S for measure and monitor the growth of standing timber material hardness, h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth;

Step 3: based on mathematics modeling, to imposed load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _ccarry out dimensional analysis, setting up measures and monitor the growth of standing timber about pressure head and institute expects the Non-di-mensional equation of correlation parameter:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

Step 4: according to described Non-di-mensional equation, the respective fine Micromechanics parameter (E, the σ that estimate in selecting step 2 and calculate _y, n, F, S, h _c), set up dimensionless functional relation:

${\mathrm{\Π}}_{\mathrm{\α}}=(\frac{{\mathrm{\σ}}_y}{E},n)=(a-\mathrm{bn}){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[c\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-\mathrm{dn}]}---\left(3\right)$

${\mathrm{\Π}}_{\mathrm{\β}}=(\frac{{\mathrm{\σ}}_y}{E},n)=e+\mathrm{fexp}\left(\mathrm{gn}\right)\exp \left[i\left(\frac{{\mathrm{\σ}}_y}{E}\right)\right]---\left(4\right)$

Wherein, a, b, c, d, e, f, g, i are fitting parameter;

Step 5: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that described specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth; Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and by described material hardness, maximum load load F and impression contact degree of depth h _cvalue be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

Step 6: by the micro-mechanical property parameter that obtains in described step 5 by plotted against depth, set up the micro-mechanical property gradient curve of surface graded material.

2. the thin Micro Mechanical Properties assessment measuring method of surface graded metal material according to claim 1, it is characterized in that, in described step 1, set up the limit element artificial module of nano indentation test, comprise: adopt two dimensional model to carry out modeling to measured and monitored the growth of standing timber material, utilize one dimension line segment to carry out modeling to pressure head, generate the initial solid model of nano indentation test; In view of the axial symmetry of model, get the limit element artificial module that 1/2nd of described initial solid model sets up nano indentation test.

3. the thin Micro Mechanical Properties assessment measuring method of surface graded metal material according to claim 1, it is characterized in that, described step 2 comprises: based on process of surface treatment and matrix material elastic modulus, estimates micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with finite element model, generate some groups of load-displacement response curves, calculate relevant position Micromechanics parameter (F, S, h _c).

4. the thin Micro Mechanical Properties assessment measuring method of surface graded metal material according to claim 1, it is characterized in that, described step 3 comprises:

Based on mathematics modeling, by pressure head loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _cbeing expressed as measures and monitor the growth of standing timber about pressure head and institute expects the function general equation of correlation parameter:

F＝F(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (5)

h _c＝h _c(h,E,ν,E _i,ν _i,σ _y,n,μ,θ) (6)

Wherein, ν for measure and monitor the growth of standing timber material Poisson ratio, E _iand ν _ibe respectively elastic modulus and the Poisson ratio of pressure head, the friction factor that μ is pressure head and institute's survey storeroom, θ is the half-angle angle of pressure head;

When not considering to be coupled between parameter, described function general equation is converted into dimensionless function:

$\frac{F}{E{h}^2}=F(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(7\right)$

$\frac{h_c}{E{h}^2}=h_c(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(8\right)$

Above-mentioned pressure head and institute measure and monitor the growth of standing timber expect parameter in, the dimension [h] only having the dimension of elastic modulus [E] and the degree of depth is independently, and other parameters all represent by the form of the exponent product of these two independent dimensions;

Omit the E in described dimensionless function _i, ν _iand μ, for the pressure head of a given angle θ, dimensionless functional relation is reduced to Non-di-mensional equation by application Π theorem further:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right).$

5. the thin Micro Mechanical Properties assessment measuring method of surface graded metal material according to claim 1, it is characterized in that, described step 5 comprises: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, obtain a series of load-displacement response curve by predetermined depth, obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and be updated in described dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

In described step 6, by the micro-mechanical property parameter that obtains in described step 5 by plotted against depth, obtain the mechanical performance gradient curve of its material.

6. a thin Micro Mechanical Properties assessment measurement mechanism for surface graded metal material, it is characterized in that, described thin Micro Mechanical Properties measuring method device comprises:

Unit set up by model, by two-dimentional modeling, gives material properties, stress and strain model, applying boundary condition etc., sets up the limit element artificial module of nano indentation test, and verify the accuracy of described limit element artificial module;

Trickle sight mechanics parameter computing unit, based on process of surface treatment and matrix material elastic modulus, estimates micro-mechanical property parameter (E, the σ of surperficial functionally gradient material (FGM) _y, n), in conjunction with described in finite element model calculate described micro-mechanical property parameter corresponding Micro Mechanical Properties parameter (F, S, h _c); Wherein, E for measure and monitor the growth of standing timber material elastic modulus, σ _yfor measure and monitor the growth of standing timber material yield stress, n for measure and monitor the growth of standing timber material strain hardening exponent, F is the loaded load on nano indentation test compressing head, S for measure and monitor the growth of standing timber material hardness, h _cfor pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact the degree of depth;

Non-di-mensional equation generation unit, based on mathematics modeling, to loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _ccarry out dimensional analysis, setting up measures and monitor the growth of standing timber about pressure head and institute expects the Non-di-mensional equation of correlation parameter:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right)$

Dimensionless correlation generation unit, according to described Non-di-mensional equation, in conjunction with the trickle sight mechanics parameter of material (E, σ that described trickle sight mechanics parameter computing unit is corresponding _y, n, F, S, h _c), set up dimensionless functional relation:

${\mathrm{\Π}}_{\mathrm{\α}}=(\frac{{\mathrm{\σ}}_y}{E},n)=(a-\mathrm{bn}){\left(\frac{{\mathrm{\σ}}_y}{E}\right)}^{[c\log \left(\frac{{\mathrm{\σ}}_y}{E}\right)-\mathrm{dn}]}---\left(3\right)$

${\mathrm{\Π}}_{\mathrm{\β}}=(\frac{{\mathrm{\σ}}_y}{E},n)=e+\mathrm{fexp}\left(\mathrm{gn}\right)\exp \left[i\left(\frac{{\mathrm{\σ}}_y}{E}\right)\right]---\left(4\right)$

Wherein, a, b, c, d, e, f, g, i are fitting parameter;

Mechanical property parameters generation unit, prepares surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that described specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth; Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and by material hardness, maximum load load F and impression contact degree of depth h _cvalue be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

Mechanical performance gradient curved unit, the micro-mechanical property parameter obtained by described mechanical property parameters generation unit, by plotted against depth, obtains the mechanical performance gradient curve of its material.

7. the thin Micro Mechanical Properties assessment measurement mechanism of surface graded metal material according to claim 6, it is characterized in that, described model set up unit specifically for: adopt two dimensional model modeling is carried out to measured and monitored the growth of standing timber material, utilize one dimension line segment to carry out modeling to pressure head, generate the initial solid model of nano indentation test; In view of the axial symmetry of model, get the limit element artificial module that 1/2nd of described initial solid model sets up nano indentation test.

8. the thin Micro Mechanical Properties assessment measurement mechanism of surface graded metal material according to claim 6, it is characterized in that, described trickle sight mechanics parameter computing unit specifically for: based on process of surface treatment and matrix material elastic modulus, estimate surperficial functionally gradient material (FGM) micro-mechanical property parameter (E, σ _y, n), in conjunction with finite element model, generate some groups of load-displacement response curves, calculate relevant position Micromechanics parameter (F, S, h _c).

9. the thin Micro Mechanical Properties assessment measurement mechanism of surface graded metal material according to claim 6, it is characterized in that, described Non-di-mensional equation generation unit comprises:

General equation generation module, for by pressure head loaded load F and pressure head with the impression between expecting of measuring and monitoring the growth of standing timber contact degree of depth h _cbeing expressed as measures and monitor the growth of standing timber about pressure head and institute expects the function general equation of correlation parameter:

F＝F(h,E,ν,Ei,νi,σ _y,n,μ,θ) (5)

h _c＝h _c(h,E,ν,Ei,ν _i,σ _y,n,μ,θ) (6)

Wherein, ν for measure and monitor the growth of standing timber material Poisson ratio, E _iand ν _ibe respectively elastic modulus and the Poisson ratio of pressure head, the friction factor that μ is pressure head and institute's survey storeroom, θ is the half-angle angle of pressure head;

Dimensionless function generation module, for when not considering to be coupled between parameter, is converted into dimensionless function by described function general equation:

$\frac{F}{E{h}^2}=F(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(7\right)$

$\frac{h_c}{E{h}^2}=h_c(\frac{h}{h},\frac{E}{E},\frac{v}{E^0{h}^0},\frac{E_i}{E},\frac{v_i}{E^0{h}^0},\frac{{\mathrm{\σ}}_y}{E},\frac{n}{E^0{h}^0},\frac{\mathrm{\μ}}{E^0{h}^0},\frac{\mathrm{\θ}}{E^0{h}^0})---\left(8\right)$

Above-mentioned pressure head and institute measure and monitor the growth of standing timber expect parameter in, the dimension [h] only having the dimension of elastic modulus [E] and the degree of depth is independently, and other parameters all represent by the form of the exponent product of these two independent dimensions;

Non-di-mensional equation generation module, for omitting the E in described dimensionless function _i, ν _iand μ, for the pressure head of a given angle θ, dimensionless functional relation is reduced to described Non-di-mensional equation by application Π theorem further:

$\frac{F}{{\mathrm{Eh}}^2}={\mathrm{\Π}}_{\mathrm{\α}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(1\right)$

$\frac{h_c}{h}={\mathrm{\Π}}_{\mathrm{\β}}[\frac{{\mathrm{\σ}}_y}{E},n]---\left(2\right).$

10. the thin Micro Mechanical Properties assessment measurement mechanism of surface graded metal material according to claim 6, it is characterized in that, mechanical property parameters generation unit specifically for: prepare surperficial functionally gradient material (FGM) Cross section polishing sample, along the depth direction that specimen surface is different, combining nano indentation test, obtains a series of load-displacement response curve by predetermined depth; Obtain material hardness, maximum load load F and impression contact degree of depth h _cvalue, and be updated in dimensionless correlation, the anti-micro-mechanical property parameter releasing surface graded material relevant position;

Described mechanical performance gradient curved unit specifically for: the micro-mechanical property parameter that described mechanical performance gradient curved unit generates is pressed plotted against depth, sets up surface graded material micro-mechanical property gradient curve.