Performance predictor for fabricated parts

• US 7,010,474 B1
• Filed: 11/03/2000
• Issued: 03/07/2006
• Est. Priority Date: 11/03/2000
• Status: Expired due to Fees

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Wang, Hsin-Pang, Dris, Irene, Gao, Dongming, Ramaswamy, Sreeganesh, Perry, Erin Marie
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): ORTIZ RODRIGUEZ, CARLOS R
• Application Number:
  US09/705,572
• Time in Patent Office: 1,950 Days
• Field of Search: 703/7, 703/9
• US Class Current: 703/7
• CPC Class Codes: G05B 19/41875 characterised by quality surveillance of production
• CPC Class Codes: G05B 2219/32194 Quality prediction
• CPC Class Codes: G05B 23/0283 Predictive maintenance, e.g. involving the monitoring of a system and, based on the monitoring results, taking decisions on the maintenance schedule of the monitored system; Estimating remaining useful life [RUL] preventive maintenance, i.e. planning maintenance according to the available resources without monitoring the system G06Q10/06
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A simulation system for generating a predicted performance for fabricated parts comprises a rheological degradation database for storing rheological degradation data for associated materials, a mechanical degradation database for storing mechanical degradation data for associated materials and a computer coupled to the rheological degradation database and the mechanical degradation database for computing part performance predictions for a respective material with a predetermined geometry under predetermined processing conditions, partially based on the rheological degradation data and the mechanical degradation data.

Claims

1. A simulation system for generating a predicted performance for fabricated parts comprising:

a rheological degradation database for storing a plurality of rheological degradation data for associated materials;

a mechanical degradation database for storing a plurality of mechanical degradation data for associated materials; and

a computer coupled to said rheological degradation database and said mechanical degradation database for computing part performance predictions for a respective material with a predetermined geometry under predetermined processing conditions, partially based on said rheological degradation data and said mechanical degradation data;

wherein a process window is generated by said computer using said mechanical degradation data and said rheological degradation data and a thinwall prediction in a mold is made.

2. A simulation system in accordance with claim 1, wherein said materials are selected from the group consisting of polymer, metal and ceramic.

3. A simulation system in accordance with claim 1, wherein said material is silicone.

4. A simulation system in accordance with claim 1, wherein said material is magnesium.

5. A simulation system in accordance with claim 1, wherein a part geometry of an object to be fabricated is imported into said computer.

6. A simulation system in accordance with claim 1, wherein said processing conditions include filling time, mold temperature and melt temperature.

7. A simulation system in accordance with claim 5, wherein said part geometry imported into said computer importing a model entails generating a CAD (computer aided design) part model of a three-dimensional object and discretizing the part model.

8. A simulation system in accordance with claim 7, wherein the three-dimensional model is discretized by enveloping the model with a finite element mesh.

9. A simulation system in accordance with claim 8, wherein a graphics software capable of decomposing a 3-D surface into a mesh of triangular or otherwise shaped elements, or facets, is used.

10. A simulation system in accordance with claim 1, wherein said computer compares said thin-wall prediction to said process window.

11. A simulation system in accordance with claim 10, wherein if the prediction falls within said process window, the simulation is complete and the said fabricated part is acceptable.

12. A simulation system in accordance with claim 10, wherein if said prediction falls outside of said process window said fabricated part or said processing conditions are unacceptable and said inputs need modification.

13. A simulation system in accordance with claim 1, wherein said thinwall prediction comprises a first filling step of size Δ

t_f and a temperature step of size Δ

t_T.

14. A simulation system in accordance with claim 13, wherein for conductive and convective terms, a time step size, Δ

t, is defined as follows;

$\mathrm{\Delta <br><br>}<br><br><br><br>t\le <br><br>\frac{1}{\frac{2<br><br>\mathrm{\alpha <br><br>}}{{\left(\mathrm{\Delta <br><br>}<br><br><br><br>z\right)}^2}+\frac{v_x}{\mathrm{\Delta <br><br>}<br><br><br><br>x}+\frac{v_y}{\mathrm{\Delta <br><br>}<br><br><br><br>y}}$

where

α

is the thermal diffusivity

Δ

z is the mesh size in the thickness (or z) direction

ν

_x is the velocity in the x flow direction

Δ

x is the mesh size in the x flow direction

ν

_y is the velocity in the y flow direction

Δ

y is the mesh size in the y flow direction.

15. A simulation system in accordance with claim 13, wherein for a viscous heating term, said time step is represented as follows:

$\mathrm{\Delta <br><br>}<br><br><br><br>t\le <br><br>\frac{\mathrm{\rho <br><br>}<br><br><br><br>C_P}{<br><br>A<br><br><br><br>C<br><br>{\stackrel{.}{\mathrm{\gamma <br><br>}}}^{B+2}<br><br>e^{\mathrm{CT}}<br><br>}$

where,

ρ

is the density

C_p is the specific heat

A, B, C are the coefficients of the Power Law viscosity model

{dot over (γ

)} is the shear rate and

T is the resin temperature.

16. A simulation system in accordance with claim 13, wherein a temperature is calculated and a pressure is calculated.

17. A simulation system in accordance with claim 16, wherein a convergence of said pressure is monitored.

18. A simulation system in accordance with claim 17, wherein if said pressure has converged, the system monitors for temperature convergence.

19. A simulation system in accordance with claim 16, wherein a convergence of said temperature is monitored.

20. A simulation system in accordance with claim 19, wherein if the temperature has converged, the system monitors whether all of the temperature steps in said thinwall prediction have been solved.

21. A simulation system in accordance with claim 20, wherein if all of the temperature steps in said thinwall prediction have not been solved, a next temperature step is processed.

22. A simulation system in accordance with claim 21, wherein if all of the temperature steps in said thinwall prediction have been solved, the system monitors whether the mold has been filled.

23. A simulation system in accordance with claim 22, wherein if the mold has not been filled, the next filling step is processed.

24. A simulation system in accordance with claim 22, wherein if the mold is full, a post-processing is done where results are written and saved to said computer.

25. A simulation system in accordance with claim 1, wherein said rheological degradation database is propagated with empirical rheological degradation data for said selected material.

26. A simulation system in accordance with claim 25, wherein a portion of said rheological degradation database is propagated by:

selecting a material to test;

measuring the viscosity of said selected material;

pre-shearing portions of said material at various shear rates;

measuring the viscosity of said pre-sheared material;

calculating the viscosity ratio between said pre-sheared material and said material to detect a pre-shear effect on said material.

27. A simulation system in accordance with claim 25, wherein a portion of said rheological database is generated by:

selecting a material to test;

measuring the viscosity of said selected material;

heating portions of said material at various temperatures;

measuring the viscosity of said heated portions;

calculating the viscosity ratio between said heated material and said material to detect a temperature effect on said material.

28. A simulation system in accordance with claim 1, wherein said mechanical degradation database is propagated with empirical mechanical degradation data for said selected material.

29. A simulation system in accordance with claim 27, wherein a portion of said mechanical degradation database is generated by:

selecting a material to test;

computing the local shear and temperature behavior of said selected material;

selecting test conditions based on behavior information to cover a broad test range;

making sample parts under the selected test conditions;

performing impact tests on said sample parts; and

performing tensile tests on said sample parts.

30. A computer generated prediction method for generating a predicated performance for a fabricated part comprising:

importing a model;

inputting a fabrication material;

inputting processing conditions;

importing rheological degradation data for said selected material;

importing mechanical degradation data for said selected material;

generating a process window;

generating a thinwall prediction; and

comparing said thinwall prediction to said process window.

31. A method for generating a predicated performance, in accordance with claim 30, wherein said step of importing a model comprises:

generating a part model; and

discretizing said part model.

32. A method for generating a predicated performance, in accordance with claim 30, wherein said step of inputting fabrication material includes:

inputting a fill time;

inputting a mold temperature; and

inputting a resin melt temperature.

33. A method for generating a predicated performance, in accordance with claim 30, wherein said step of inputting a fabrication material is selected from the group consisting of polymer, metal and ceramic.

34. A method for generating a predicated performance, in accordance with claim 30, wherein said step of importing rheological degradation data for said selected material comprises:

importing said rheological degradation data from a rheological degradation database.

35. A method for generating a predicated performance, in accordance with claim 34, wherein said rheological database is generated by:

selecting a material to test;

measuring the viscosity of said selected material;

heating portions of said material at various temperatures;

measuring the viscosity of said heated portions;

calculating a viscosity ratio between said heated material and said material to detect a temperature effect on said material.

36. A method for generating a predicated performance, in accordance with claim 30, wherein said step of importing mechanical degradation data for said selected material comprises:

importing said mechanical degradation data from a mechanical degradation database.

37. A method for generating a predicated performance, in accordance with claim 36, wherein said mechanical database is generated by:

selecting a material to test;

computing the local shear and temperature behavior of said selected material;

selecting test conditions based on behavior information to cover a broad test range;

making sample parts under the selected test conditions;

performing impact tests on said sample parts; and

performing tensile tests on said sample parts.

38. Computer-readable media tangibly embodying a program of instructions executable by a computer to perform a computer generated prediction method for a fabricated part, the method comprising;

importing a model;

inputting a fabrication material;

inputting processing conditions;

importing rheological degradation data for said selected material;

importing mechanical degradation data for said selected material;

generating a process window;

generating a thinwall prediction; and

comparing said thinwall prediction to said process window.

39. Computer-readable media tangibly embodying a program of instructions in accordance with claim 38, wherein said media comprise at least one of a RAM, A ROM, a disk, a CDROM, a DVDROM, an ASIC and a PROM.

40. A computer generated prediction method of generating a predicated performance for a fabricated part, the method comprising:

means for importing a model;

means for inputting a fabrication material;

means for inputting processing conditions;

means for importing rheological degradation data for said selected material;

means for importing mechanical degradation data for said selected material;

means for generating a process window;

means for generating a thinwall prediction; and

means for comparing said thinwall prediction to said process window.