Fatigue resistance at filleted corners - Design detail
Clash Royale CLAN TAG#URR8PPP
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So, I have a situation where we are putting load on a plate from above, and the plate has a step in it, which was made by milling a bigger block of steel (i.e. there are no layers and everything is homogeneous). Conventional engineering knowledge tells us that if we increase the fillet radii, we will get a better fatigue performance for this abrupt change in EI within this plate, which is great. But a bigger fillet will also mean the item that this plate is supporting (which in this case fits into the milled area) becomes a limiting factor with how sharp their corners are. I would like to know - is there a fillet design that I can use in this situation that will allow me to improve fatigue performance without necessarily compromising the way my object fits into this milled area? I have proposed some different versions in the sketch attached, and I would like someone well versed in this area to help me understand which one is best, and for what reasons. Thanks!
]1
fatigue
asked 4 hours ago
Isa
863
add a comment |
up vote
1
down vote
favorite
So, I have a situation where we are putting load on a plate from above, and the plate has a step in it, which was made by milling a bigger block of steel (i.e. there are no layers and everything is homogeneous). Conventional engineering knowledge tells us that if we increase the fillet radii, we will get a better fatigue performance for this abrupt change in EI within this plate, which is great. But a bigger fillet will also mean the item that this plate is supporting (which in this case fits into the milled area) becomes a limiting factor with how sharp their corners are. I would like to know - is there a fillet design that I can use in this situation that will allow me to improve fatigue performance without necessarily compromising the way my object fits into this milled area? I have proposed some different versions in the sketch attached, and I would like someone well versed in this area to help me understand which one is best, and for what reasons. Thanks!]1
fatigue
asked 4 hours ago
Isa
863
Are you experiencing fatigue cracks? You don't mention if this is an actual issue. If you are not seeing cracks, you may be over-thinking (and over-complicating) this.
– hazzey♦
3 hours ago
Accordingly, are the forces on the plate being applied vertically, horizontally or both? Vertical forces should not require a fillet and horizontal forces will be handled by the mass around the cut, somewhat independent of the fillet. I agree with the over-thinking and over-complicating possibility.
– fred_dot_u
1 hour ago
@hazzey Yea, we have cracks. A plate cracked into 6 pieces all clean at the seam. Pretty sure it's fatigue, it shouldn't be as straight along the cut line if it wasn't. Didn't really have the chance to do fracture analysis either at this point, but I am almost certain we will see fatigue marks when we do have the chance to (and we plan to).
– Isa
13 mins ago
@fred_dot_u Vertical forces, but I disagree with your assessment. Anything flexes under load - that produce fatigue issues. For your info, we are talking 20T loads with impact force factors of 4+ generally. So it is generally around 40T average loads with 160T ish max spikes at times. Target life approximately 12MM cycles to 16MM cycles.
– Isa
10 mins ago
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
So, I have a situation where we are putting load on a plate from above, and the plate has a step in it, which was made by milling a bigger block of steel (i.e. there are no layers and everything is homogeneous). Conventional engineering knowledge tells us that if we increase the fillet radii, we will get a better fatigue performance for this abrupt change in EI within this plate, which is great. But a bigger fillet will also mean the item that this plate is supporting (which in this case fits into the milled area) becomes a limiting factor with how sharp their corners are. I would like to know - is there a fillet design that I can use in this situation that will allow me to improve fatigue performance without necessarily compromising the way my object fits into this milled area? I have proposed some different versions in the sketch attached, and I would like someone well versed in this area to help me understand which one is best, and for what reasons. Thanks!]1
fatigue
asked 4 hours ago
Isa
863
So, I have a situation where we are putting load on a plate from above, and the plate has a step in it, which was made by milling a bigger block of steel (i.e. there are no layers and everything is homogeneous). Conventional engineering knowledge tells us that if we increase the fillet radii, we will get a better fatigue performance for this abrupt change in EI within this plate, which is great. But a bigger fillet will also mean the item that this plate is supporting (which in this case fits into the milled area) becomes a limiting factor with how sharp their corners are. I would like to know - is there a fillet design that I can use in this situation that will allow me to improve fatigue performance without necessarily compromising the way my object fits into this milled area? I have proposed some different versions in the sketch attached, and I would like someone well versed in this area to help me understand which one is best, and for what reasons. Thanks!]1
fatigue
fatigue
asked 4 hours ago
Isa
863
asked 4 hours ago
Isa
863
asked 4 hours ago
Isa
863
asked 4 hours ago
Isa
863
asked 4 hours ago
Isa
863
863
Are you experiencing fatigue cracks? You don't mention if this is an actual issue. If you are not seeing cracks, you may be over-thinking (and over-complicating) this.
– hazzey♦
3 hours ago
Accordingly, are the forces on the plate being applied vertically, horizontally or both? Vertical forces should not require a fillet and horizontal forces will be handled by the mass around the cut, somewhat independent of the fillet. I agree with the over-thinking and over-complicating possibility.
– fred_dot_u
1 hour ago
@hazzey Yea, we have cracks. A plate cracked into 6 pieces all clean at the seam. Pretty sure it's fatigue, it shouldn't be as straight along the cut line if it wasn't. Didn't really have the chance to do fracture analysis either at this point, but I am almost certain we will see fatigue marks when we do have the chance to (and we plan to).
– Isa
13 mins ago
@fred_dot_u Vertical forces, but I disagree with your assessment. Anything flexes under load - that produce fatigue issues. For your info, we are talking 20T loads with impact force factors of 4+ generally. So it is generally around 40T average loads with 160T ish max spikes at times. Target life approximately 12MM cycles to 16MM cycles.
– Isa
10 mins ago
add a comment |
Are you experiencing fatigue cracks? You don't mention if this is an actual issue. If you are not seeing cracks, you may be over-thinking (and over-complicating) this.
– hazzey♦
3 hours ago
Accordingly, are the forces on the plate being applied vertically, horizontally or both? Vertical forces should not require a fillet and horizontal forces will be handled by the mass around the cut, somewhat independent of the fillet. I agree with the over-thinking and over-complicating possibility.
– fred_dot_u
1 hour ago
@hazzey Yea, we have cracks. A plate cracked into 6 pieces all clean at the seam. Pretty sure it's fatigue, it shouldn't be as straight along the cut line if it wasn't. Didn't really have the chance to do fracture analysis either at this point, but I am almost certain we will see fatigue marks when we do have the chance to (and we plan to).
– Isa
13 mins ago
@fred_dot_u Vertical forces, but I disagree with your assessment. Anything flexes under load - that produce fatigue issues. For your info, we are talking 20T loads with impact force factors of 4+ generally. So it is generally around 40T average loads with 160T ish max spikes at times. Target life approximately 12MM cycles to 16MM cycles.
– Isa
10 mins ago
Are you experiencing fatigue cracks? You don't mention if this is an actual issue. If you are not seeing cracks, you may be over-thinking (and over-complicating) this.
– hazzey♦
3 hours ago
Are you experiencing fatigue cracks? You don't mention if this is an actual issue. If you are not seeing cracks, you may be over-thinking (and over-complicating) this.
– hazzey♦
3 hours ago
Accordingly, are the forces on the plate being applied vertically, horizontally or both? Vertical forces should not require a fillet and horizontal forces will be handled by the mass around the cut, somewhat independent of the fillet. I agree with the over-thinking and over-complicating possibility.
– fred_dot_u
1 hour ago
Accordingly, are the forces on the plate being applied vertically, horizontally or both? Vertical forces should not require a fillet and horizontal forces will be handled by the mass around the cut, somewhat independent of the fillet. I agree with the over-thinking and over-complicating possibility.
– fred_dot_u
1 hour ago
@hazzey Yea, we have cracks. A plate cracked into 6 pieces all clean at the seam. Pretty sure it's fatigue, it shouldn't be as straight along the cut line if it wasn't. Didn't really have the chance to do fracture analysis either at this point, but I am almost certain we will see fatigue marks when we do have the chance to (and we plan to).
– Isa
13 mins ago
@hazzey Yea, we have cracks. A plate cracked into 6 pieces all clean at the seam. Pretty sure it's fatigue, it shouldn't be as straight along the cut line if it wasn't. Didn't really have the chance to do fracture analysis either at this point, but I am almost certain we will see fatigue marks when we do have the chance to (and we plan to).
– Isa
13 mins ago
@fred_dot_u Vertical forces, but I disagree with your assessment. Anything flexes under load - that produce fatigue issues. For your info, we are talking 20T loads with impact force factors of 4+ generally. So it is generally around 40T average loads with 160T ish max spikes at times. Target life approximately 12MM cycles to 16MM cycles.
– Isa
10 mins ago
@fred_dot_u Vertical forces, but I disagree with your assessment. Anything flexes under load - that produce fatigue issues. For your info, we are talking 20T loads with impact force factors of 4+ generally. So it is generally around 40T average loads with 160T ish max spikes at times. Target life approximately 12MM cycles to 16MM cycles.
– Isa
10 mins ago
add a comment |
1 Answer
1
active
oldest
votes
up vote
3
down vote
I have seen 'lollipop cutters' used for this purpose, just a single pass into the side (closest to option B). The thickness of the shank means it's not a perfectly square bottomed slot, but was sufficient in the instance in question.
The image below is just to show the cutter type, not the fillet shape! Am on mobile so can't draw a diagram just now.
In terms of being the best option or not, it was picked because it was easy to manufacture, and unit cost was important. Without more information on your application it's hard to make a specific judgement.
answered 3 hours ago
Jonathan R Swift
2,971419
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
I have seen 'lollipop cutters' used for this purpose, just a single pass into the side (closest to option B). The thickness of the shank means it's not a perfectly square bottomed slot, but was sufficient in the instance in question.
The image below is just to show the cutter type, not the fillet shape! Am on mobile so can't draw a diagram just now.
In terms of being the best option or not, it was picked because it was easy to manufacture, and unit cost was important. Without more information on your application it's hard to make a specific judgement.
answered 3 hours ago
Jonathan R Swift
2,971419
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
add a comment |
up vote
3
down vote
I have seen 'lollipop cutters' used for this purpose, just a single pass into the side (closest to option B). The thickness of the shank means it's not a perfectly square bottomed slot, but was sufficient in the instance in question.
The image below is just to show the cutter type, not the fillet shape! Am on mobile so can't draw a diagram just now.
In terms of being the best option or not, it was picked because it was easy to manufacture, and unit cost was important. Without more information on your application it's hard to make a specific judgement.
answered 3 hours ago
Jonathan R Swift
2,971419
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
add a comment |
up vote
3
down vote
up vote
3
down vote
I have seen 'lollipop cutters' used for this purpose, just a single pass into the side (closest to option B). The thickness of the shank means it's not a perfectly square bottomed slot, but was sufficient in the instance in question.
The image below is just to show the cutter type, not the fillet shape! Am on mobile so can't draw a diagram just now.
In terms of being the best option or not, it was picked because it was easy to manufacture, and unit cost was important. Without more information on your application it's hard to make a specific judgement.
answered 3 hours ago
Jonathan R Swift
2,971419
I have seen 'lollipop cutters' used for this purpose, just a single pass into the side (closest to option B). The thickness of the shank means it's not a perfectly square bottomed slot, but was sufficient in the instance in question.
The image below is just to show the cutter type, not the fillet shape! Am on mobile so can't draw a diagram just now.
In terms of being the best option or not, it was picked because it was easy to manufacture, and unit cost was important. Without more information on your application it's hard to make a specific judgement.
answered 3 hours ago
Jonathan R Swift
2,971419
answered 3 hours ago
Jonathan R Swift
2,971419
answered 3 hours ago
Jonathan R Swift
2,971419
answered 3 hours ago
Jonathan R Swift
2,971419
2,971419
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
add a comment |
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
Okay, what info do you need? I really just want someone to explain whether creating a groove with a bigger radii will actually still help fatigue performance or not, or will it cause more issues than it's worth to try. And yes, manufacturing costs are important, but only as important as the application. Costs are relevant and I wanted to put that factor aside for the purpose of this question (I am sure we will look at it from that perspective when we have a good solution we are comfortable with longer term).
– Isa
7 mins ago
add a comment |
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Are you experiencing fatigue cracks? You don't mention if this is an actual issue. If you are not seeing cracks, you may be over-thinking (and over-complicating) this.
– hazzey♦
3 hours ago
Accordingly, are the forces on the plate being applied vertically, horizontally or both? Vertical forces should not require a fillet and horizontal forces will be handled by the mass around the cut, somewhat independent of the fillet. I agree with the over-thinking and over-complicating possibility.
– fred_dot_u
1 hour ago
@hazzey Yea, we have cracks. A plate cracked into 6 pieces all clean at the seam. Pretty sure it's fatigue, it shouldn't be as straight along the cut line if it wasn't. Didn't really have the chance to do fracture analysis either at this point, but I am almost certain we will see fatigue marks when we do have the chance to (and we plan to).
– Isa
13 mins ago
@fred_dot_u Vertical forces, but I disagree with your assessment. Anything flexes under load - that produce fatigue issues. For your info, we are talking 20T loads with impact force factors of 4+ generally. So it is generally around 40T average loads with 160T ish max spikes at times. Target life approximately 12MM cycles to 16MM cycles.
– Isa
10 mins ago