Intraluminal medical device having asymetrical members and method for optimization
This invention relates generally to expandable intraluminal medical devices for use within a body passageway or duct, and more particularly to an optimized stent having asymmetrical strut and loop members and the method for designing and optimizing said strut and loop members in a continuously variable fashion. In one embodiment of the invention the resulting stent includes one or more members each having at least one component. The component has non-uniform cross-sections to achieve near-uniform stress distribution along the component when the component undergoes deformation.
1 . A method for making an improved stent comprising: inputting representative geometric, material, and boundary conditions inputs;
and solving the numerical representation to determine a resultant value at a location within a continuum defined by said representative inputs.
2 . The method of claim 1 wherein the boundary conditions are loads.
3 . The method of claim 1 wherein the boundary conditions are displacements.
4 . The method of claim 1 wherein the boundary conditions are combinations of loads and displacements.
5 . A method for making an improved stent comprising: inputting representative geometric, material, and boundary conditions inputs; solving the numerical representation to determine a resultant value at a location within a continuum defined by said representative inputs; comparing the resultant value with a target value; modifying said representative inputs in a continuously variable fashion; re-solving for the resultant value; and calculating the difference between the resultant value and the target value.
6 . The method of claim 5 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the resultant value and the target value, are repeated until the calculated difference is a maximum value.
7 . The method of claim 5 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the resultant value and the target value, are repeated until the calculated difference is a minimum value.
8 . The method of claim 7 wherein the minimum value is zero.
9 . A method for making an improved stent comprising: inputting representative geometric, material, and boundary conditions inputs; solving the numerical representation to determine a resultant value at a location within a continuum defined by said representative inputs; comparing the resultant value with a target value; modifying said representative inputs in a continuously variable fashion; re-solving for the resultant value; and calculating the difference between the target value and the resultant value.
10 . The method of claim 9 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the target value and the resultant value, are repeated until the calculated difference is a maximum value.
11 . The method of claim 9 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the target value and the resultant value, are repeated until the calculated difference is a minimum value.
12 . The method of claim 11 wherein the minimum value is zero.
13 . The method of claim 5 wherein the target and resultant values represent a geometric value.
14 . The method of claim 13 wherein said geometric value is an one-dimensional measure.
15 . The method of claim 13 wherein said geometric value is a two-dimensional measure.
16 . The method of claim 13 wherein said geometric value is a dimensional measure to the third power.
17 . The method of claim 13 wherein said geometric value is a dimensional measure to the fourth power.
18 . The method of claim 5 wherein the target and resultant values represent a material value.
19 . The method of claim 18 wherein said material value is a measure of a mechanical property of the material.
20 . The method of claim 18 wherein said material value is a measure of the stress state of the material.
21 . The method of claim 18 wherein said material value is a measure of the strain state of the material.
22 . The method of claim 5 wherein the target and resultant values represent a boundary condition value.
23 . The method of claim 22 wherein said boundary condition value is a measure of applied loading upon said continuum defined by said representative inputs.
24 . The method of claim 22 wherein said boundary condition value is a measure of applied displacements upon said continuum defined by said representative inputs.
25 . A method for making an improved stent comprising: inputting representative geometric, material, and boundary conditions inputs; solving the numerical representation to determine a resultant value at a location within a continuum defined by said representative inputs; comparing the resultant value with a target value; modifying said representative inputs in a continuously variable fashion; re-solving for the resultant value; and calculating the ratio of the resultant value to the target value.
26 . The method of claim 25 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the ratio of the resultant value to the target value are repeated until the calculated ratio is a maximum value.
27 . The method of claim 25 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the ratio of the resultant value to the target value are repeated until the calculated ratio is a minimum value.
28 . The method of claim 25 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the ratio of the resultant value to the target value are repeated until the calculated ratio is equivalent to unity.
29 . The method of claim 25 wherein the calculated ratio represents a Factor of Safety.
30 . A method for making an improved stent comprising using a numerical methodology to minimize strains and maximize fatigue safety factors in the stent structure utilizing an undisrupted continuum.
31 . A method for making an improved stent comprising using a numerical methodology to maximize fatigue safety factors in the stent structure utilizing a disrupted continuum.
32 . The method of claim 31 wherein said disruption is a geometric discontinuity.
33 . The method of claim 32 wherein said geometric discontinuity is selected from the group consisting of cracks, flaws, fissures, voids, and grain boundaries.
34 . The method of claim 31 wherein said disruption is a material discontinuity.
35 . A method for making an improved stent having a disruption comprising: inputting representative geometric, material, and boundary conditions inputs; solving the numerical representation to determine a resultant value at a location within a disrupted continuum defined by said representative inputs; comparing the resultant value with a target value; modifying said representative inputs in a continuously variable fashion; re-solving for the resultant value; and calculating the difference between the resultant value and the target value.
36 . The method of claim 34 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the resultant value and the target value, are repeated until the calculated difference is a maximum value.
37 . The method of claim 34 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the resultant value and the target value, are repeated until the calculated difference is a minimum value.
38 . The method of claim 36 wherein the minimum value is zero.
39 . A method for making an improved stent having a disruption comprising: inputting representative geometric, material, and boundary conditions inputs; solving the numerical representation to determine a resultant value at a location within a disrupted continuum defined by said representative inputs; comparing the resultant value with a target value; modifying said representative inputs in a continuously variable fashion; re-solving for the resultant value; and calculating the difference between the target value and the resultant value.
40 . The method of claim 39 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the target value and the resultant value, are repeated until the calculated difference is a maximum value.
41 . The method of claim 39 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the difference between the target value and the resultant value, are repeated until the calculated difference is a minimum value.
42 . The method of claim 41 wherein the minimum value is zero.
43 . The method of claim 35 wherein the target and resultant values represent a geometric value.
44 . The method of claim 43 wherein said geometric value is an one-dimensional measure.
45 . The method of claim 43 wherein said geometric value is a two-dimensional measure.
46 . The method of claim 43 wherein said geometric value is a dimensional measure to the third power.
47 . The method of claim 43 wherein said geometric value is a dimensional measure to the fourth power.
48 . The method of claim 35 wherein the target and resultant values represent a material value.
49 . The method of claim 48 wherein said material value is a measure of a mechanical/physical property of the material.
50 . The method of claim 48 wherein said material value is a measure of the stress state of the material.
51 . The method of claim 48 wherein said material value is a measure of the strain state of the material.
52 . The method of claim 35 wherein the target and resultant values represent a boundary condition value.
53 . The method of claim 52 wherein said boundary condition value is a measure of applied loading upon the continuum defined by said inputs.
54 . The method of claim 52 wherein said boundary condition value is a measure of applied displacements upon the continuum defined by said inputs.
55 . A method for making an improved stent having a disruption comprising: inputting representative geometric, material, and boundary conditions inputs; solving the numerical representation to determine a resultant value at a location within a disrupted continuum defined by said representative inputs; comparing the resultant value with a target value; modifying said representative inputs in a continuously variable fashion; re-solving for the resultant value; and calculating the ratio of the resultant value to the target value.
56 . The method of claim 55 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the ratio of the resultant value to the target value are repeated until the calculated ratio is a maximum value.
57 . The method of claim 55 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the ratio of the resultant value to the target value are repeated until the calculated ratio is a minimum value.
58 . The method of claim 55 wherein the steps of modifying said representative inputs in a continuously variable fashion, re-solving for the resultant value, and calculating the ratio of the resultant value to the target value are repeated until the calculated ratio is equivalent to unity.
59 . The method of claim 55 wherein the calculated ratio represents a Factor of Safety.
60 . The method of claim 5 wherein additional resultant values are determined at locations within the disrupted continuum and compared to additional corresponding target values.
61 . The method of claim 9 wherein additional resultant values are determined at locations within the disrupted continuum and compared to additional corresponding target values.
62 . The method of claim 35 wherein additional resultant values are determined at locations within the disrupted continuum and compared to additional corresponding target values.
63 . The method of claim 39 wherein additional resultant values are determined at locations within the disrupted continuum and compared to additional corresponding target values.
64 . The method of claim 35 wherein the resultant value is a stress intensity factor and the target value is fracture toughness.
65 . The method of claim 64 wherein said representative inputs and numerical representation represent the stent condition during the crimped state.
66 . The method of claim 64 wherein said representative inputs and numerical representation represent the stent condition during deployment of the stent.
67 . The method of claim 64 wherein said representative inputs and numerical representation represent the stent condition during the recoil phase.
68 . The method of claim 64 wherein said representative inputs and numerical representation represent the stent condition during in-service fatigue loading.
69 . The method of claim 39 wherein the resultant value is a stress intensity factor and the target value is fracture toughness.
70 . The method of claim 69 wherein said representative inputs and numerical representation represent the stent condition during the crimped state.
71 . The method of claim 69 wherein said representative inputs and numerical representation represent the stent condition during deployment of the stent.
72 . The method of claim 69 wherein said representative inputs and numerical representation represent the stent condition during the recoil phase.
73 . The method of claim 69 wherein said representative inputs and numerical representation represent the stent condition during in-service fatigue loading.
74 . The method of claim 35 wherein the resultant value is a stress intensity factor range and the target value is a material threshold stress intensity range.
75 . The method of claim 74 wherein said representative inputs and numerical representation represent the stent condition during in-service fatigue loading.
76 . The method of claim 74 wherein the resultant value is a stress state and the target value is an experimentally derived material crack growth rate.
77 . The method of claim 76 further comprising the step of predicting the useful stent life.
78 . The method of claim 76 wherein said representative inputs and numerical representation represent the stent condition during in-service fatigue loading.
79 . The method of claim 39 wherein the resultant value is a stress intensity factor range and the target value is a material threshold stress intensity range.
80 . The method of claim 79 wherein said representative inputs and numerical representation represent the stent condition during in-service fatigue loading.
81 . The method of claim 79 wherein the resultant value is a stress state and the target value is an experimentally derived material crack growth rate.
82 . The method of claim 81 further comprising the step of predicting the useful stent life.
83 . The method of claim 79 wherein said representative inputs and numerical representation represent the stent condition during in-service fatigue loading.