bolt design

21
Intro Page 1 BACKGROUND This calculation doesn't provide the number of bolts, but usually, many small bol The follow-up step is to tighten these bolts as much as possible, for fear that t While there are a number of more subtle joint design issues, this very basic desi Most textbooks apply the safety factor to the bolt strength, while most practicio Simply stated, this is because a safety factor of 1.2 satisfies nobody, while the There are two basic situations to be considered in evaluating the behavior of the BOLTED JOINT BEHAVIOR When a bolt is tightened, its grip is stretched by the bolt preload force (Fi). compressed by this same preload force (Fi). When an external load (P) is later a the second Figure. As the applied load is increased, the joint clamping force wi will separate or unseat. Beyond the unseating load, the bolt tension (Fb) is equ joint in compression) is the basic method used to evaluate bolted joints. The fi to provide a simple graphical basis for understanding. From this graph, it shoul to choose the bolt preload that roughly matches the bolt strength to joint unseat opening statement, ...that the needed bolt section area (At) is roughly the joint The somewhat curious note is that bolts are often preloaded to 60-90% of proof st applied to the joint ...without overloading the bolt ! as the force divided by resulting deflection. The bolt is a cylinder that experi constant (Kb) is simply the elastic modulus (Eb) times the tensile stress area (A distribution of stresss and strains in the joint is both very non-uniform, and a practice is to define an '"equivalent spring region" around each bolt. as illustr small ends are meant to represent the head and nut areas, while the conical shape the middle of the joint. A simple approximation for the spring constant of this very lengthy analysis, this should be considered a reasonable approximation that equal (assuming the joint doesn't unseat). This means that the ratio of spring f spring constants. GENERAL COMMENTS The most basic design calculation for bolted joints is to divide the joint load ( to obtain the needed bolt cross section area (At). And, of course, a design safety factor m * When tightening the bolt, the force (Fb) stretching the bolt must be equal t * When loads are applied to the joint, the length changes in the bolt (Db) and combined forces: bolt (Fb), joint (Fm), and applied (P) must balance as illustrated by the top Figure. At the same time, this load (P) decreases the not there, which is illustrated by the dashed and solid lines in the top Figure. The important "joint stiffness fraction" (C) is obtained from the parallel spring model. The "joint stiffness fraction" (C) is obtained from the parallel spring model. The joint an

Upload: thulasikrishna

Post on 23-Oct-2015

52 views

Category:

Documents


2 download

DESCRIPTION

bolt design

TRANSCRIPT

Page 1: Bolt Design

Intro

Page 1

BACKGROUND

This calculation doesn't provide the number of bolts, but usually, many small bolts are better than a few large bolts.

The follow-up step is to tighten these bolts as much as possible, for fear that they might come loose in service.

While there are a number of more subtle joint design issues, this very basic design approach is surprizingly good !

Most textbooks apply the safety factor to the bolt strength, while most practicioners prefer the safety factor on joint loads.

Simply stated, this is because a safety factor of 1.2 satisfies nobody, while the safety factor of 4 means bolts may come loose.

There are two basic situations to be considered in evaluating the behavior of the bolted joint:

BOLTED JOINT BEHAVIOR

When a bolt is tightened, its grip is stretched by the bolt preload force (Fi). At the same time, the joint (or members) are

compressed by this same preload force (Fi). When an external load (P) is later applied to the joint, the bolt stretches more,

the second Figure. As the applied load is increased, the joint clamping force will approach zero, where upon the joint halves

will separate or unseat. Beyond the unseating load, the bolt tension (Fb) is equal to the joint load (P) ...as if the joint were

joint in compression) is the basic method used to evaluate bolted joints. The first two Figures are combined in the third,

to provide a simple graphical basis for understanding. From this graph, it should be apparent that the designer would like

to choose the bolt preload that roughly matches the bolt strength to joint unseating load. This is the justification for the

opening statement, ...that the needed bolt section area (At) is roughly the joint load (P) divided by the proof stress (Sp).

The somewhat curious note is that bolts are often preloaded to 60-90% of proof strength, and then a similar load can be

applied to the joint ...without overloading the bolt !

as the force divided by resulting deflection. The bolt is a cylinder that experiences uniform stretch, which means the spring

constant (Kb) is simply the elastic modulus (Eb) times the tensile stress area (At) divided by the grip length (L). The

distribution of stresss and strains in the joint is both very non-uniform, and a subject for lengthy analysis. The common

practice is to define an '"equivalent spring region" around each bolt. as illustrated by the cones in the second Figure. The

small ends are meant to represent the head and nut areas, while the conical shapes reflect the spreading of stresses in

the middle of the joint. A simple approximation for the spring constant of this volume is provided on the right. To avoid

very lengthy analysis, this should be considered a reasonable approximation that is neither precise, or highly repeatible.

equal (assuming the joint doesn't unseat). This means that the ratio of spring force changes is the same as the ratio of

spring constants.

GENERAL COMMENTS

The factors to be considered (failure modes, or limiting cases) in the selection of the bolt preload are:

1. Tensile yielding or failure in the bolt grip material.

The most basic design calculation for bolted joints is to divide the joint load (Pmax) by the bolt proof stress (Sp

to obtain the needed bolt cross section area (At). And, of course, a design safety factor must also be included !

* When tightening the bolt, the force (Fb) stretching the bolt must be equal to the force compressing the joint (F

* When loads are applied to the joint, the length changes in the bolt (Db) and joint (Dm) must be equal. Also, the

combined forces: bolt (Fb), joint (Fm), and applied (P) must balance (S F = 0).

as illustrated by the top Figure. At the same time, this load (P) decreases the joint (or member) compression, illustrated by

not there, which is illustrated by the dashed and solid lines in the top Figure. This parallel spring model (bolt in tension, and

The important "joint stiffness fraction" (C) is obtained from the parallel spring model. A spring constant (K) is defined

The "joint stiffness fraction" (C) is obtained from the parallel spring model. The joint and member spring deflections must be

Page 2: Bolt Design

Intro

Page 2

2. Compressive yielding (crush) of the joint material under the bolt head or nut.

3. Unseating (or seperation) of the joint halves.

4. Shear failure (or strippiing) of the threads at the thread major diameter.

So, for example, if the bolts are loose, the allowable joint loads would be limited by premature joint unseating

At first glance, it would appear that the desired preload is the value that would maximize the allowed joint load is the case

that would produce simultaneous failures by all four modes above. However, this approach tends to be modified when the

consequences of each of the failure modes are considered. The first two modes tend to be somewhat "forgiving", while the

last two tend to be more serious concerns. With ductile materials, a small amount of yielding will stretch the bolt or crush the

joint, which often has the net effect of relaxing the preload (Fi) to the value that should have been selected. However this also

reduces the service safety factors. If these chosen safety factors were generous, the results may still be acceptable.

Joint unseating tends to be more catistrophic because even small side loads will cause abrasive wear of the joint asperities

which very quickly reduces the bolt preload to zero (loose bolts). Stripping threads also tends to be a catastropic failure mode

because they usually "strip one at a time" in cascading manner that quickly reduces the joint load capacity. These observations

help to justify the general practice, which is to "error on the tight side", so long as the engaged thread length is adequate. A final

note on joint shear loads is needed. Bolts are intended to be tension members, so large shear loads can be very troublesome.

The only resistance for shear loads is friction between the joint halves, which suggests a large number of bolts and high clamping

forces. The designer should consider the common practice of "cross bolting".

A related area of great interest is designing for fatigue loading. Since the fatigue strength is so much lower that the yield strength,

the designer is often tempted to consider low bolt preloads, for fear of fatigue failures in the bolts. However by clever joint design

(low C) the alternating loads in the bolt can be significantly reduced. The joint alternating loads remain high, but it is in compression,

where fatigue is rarely a concern. So with a large number of bolts, and a large preload the ratio of bolt alternating to mean stress

can be reduced to a low ratio where the bolt material failure is governed by yielding, rather than fatigue.

Page 3: Bolt Design

Intro

Page 3

This calculation doesn't provide the number of bolts, but usually, many small bolts are better than a few large bolts.

The follow-up step is to tighten these bolts as much as possible, for fear that they might come loose in service.

While there are a number of more subtle joint design issues, this very basic design approach is surprizingly good !

Most textbooks apply the safety factor to the bolt strength, while most practicioners prefer the safety factor on joint loads.

Simply stated, this is because a safety factor of 1.2 satisfies nobody, while the safety factor of 4 means bolts may come loose.

When a bolt is tightened, its grip is stretched by the bolt preload force (Fi). At the same time, the joint (or members) are

compressed by this same preload force (Fi). When an external load (P) is later applied to the joint, the bolt stretches more,

the second Figure. As the applied load is increased, the joint clamping force will approach zero, where upon the joint halves

will separate or unseat. Beyond the unseating load, the bolt tension (Fb) is equal to the joint load (P) ...as if the joint were

joint in compression) is the basic method used to evaluate bolted joints. The first two Figures are combined in the third,

to provide a simple graphical basis for understanding. From this graph, it should be apparent that the designer would like

to choose the bolt preload that roughly matches the bolt strength to joint unseating load. This is the justification for the

opening statement, ...that the needed bolt section area (At) is roughly the joint load (P) divided by the proof stress (Sp).

The somewhat curious note is that bolts are often preloaded to 60-90% of proof strength, and then a similar load can be

as the force divided by resulting deflection. The bolt is a cylinder that experiences uniform stretch, which means the spring

constant (Kb) is simply the elastic modulus (Eb) times the tensile stress area (At) divided by the grip length (L). The

distribution of stresss and strains in the joint is both very non-uniform, and a subject for lengthy analysis. The common

practice is to define an '"equivalent spring region" around each bolt. as illustrated by the cones in the second Figure. The

small ends are meant to represent the head and nut areas, while the conical shapes reflect the spreading of stresses in

the middle of the joint. A simple approximation for the spring constant of this volume is provided on the right. To avoid

very lengthy analysis, this should be considered a reasonable approximation that is neither precise, or highly repeatible.

equal (assuming the joint doesn't unseat). This means that the ratio of spring force changes is the same as the ratio of

) by the bolt proof stress (Sp)

And, of course, a design safety factor must also be included !

* When tightening the bolt, the force (Fb) stretching the bolt must be equal to the force compressing the joint (Fm).

) must be equal. Also, the

) compression, illustrated by

parallel spring model (bolt in tension, and

(C) is obtained from the parallel spring model. A spring constant (K) is defined

(C) is obtained from the parallel spring model. The joint and member spring deflections must be

Page 4: Bolt Design

Intro

Page 4

So, for example, if the bolts are loose, the allowable joint loads would be limited by premature joint unseating

At first glance, it would appear that the desired preload is the value that would maximize the allowed joint load is the case

that would produce simultaneous failures by all four modes above. However, this approach tends to be modified when the

consequences of each of the failure modes are considered. The first two modes tend to be somewhat "forgiving", while the

last two tend to be more serious concerns. With ductile materials, a small amount of yielding will stretch the bolt or crush the

joint, which often has the net effect of relaxing the preload (Fi) to the value that should have been selected. However this also

reduces the service safety factors. If these chosen safety factors were generous, the results may still be acceptable.

Joint unseating tends to be more catistrophic because even small side loads will cause abrasive wear of the joint asperities

which very quickly reduces the bolt preload to zero (loose bolts). Stripping threads also tends to be a catastropic failure mode

because they usually "strip one at a time" in cascading manner that quickly reduces the joint load capacity. These observations

help to justify the general practice, which is to "error on the tight side", so long as the engaged thread length is adequate. A final

note on joint shear loads is needed. Bolts are intended to be tension members, so large shear loads can be very troublesome.

The only resistance for shear loads is friction between the joint halves, which suggests a large number of bolts and high clamping

A related area of great interest is designing for fatigue loading. Since the fatigue strength is so much lower that the yield strength,

the designer is often tempted to consider low bolt preloads, for fear of fatigue failures in the bolts. However by clever joint design

(low C) the alternating loads in the bolt can be significantly reduced. The joint alternating loads remain high, but it is in compression,

where fatigue is rarely a concern. So with a large number of bolts, and a large preload the ratio of bolt alternating to mean stress

Page 5: Bolt Design

Math

Page 5

Background Discussion & Comments Using these .xls worksheets

BOLT INSTALLATION * The intent was to automate the joint analysis details,

* bolt torque to Initial Bolt Tension relation (approx) so the user can "what if" pick the % of yield for the bolt and thread

… bolt tension = joint compression * The tab labels indicate: bolt mat'l, grip mat'l, and thread mat'l

note: the running torque of locking features should be added to this desired preload * The left block provides the bolt installation torque

* Bolt tension to nominal stress (approx) relation * This torque is the lower of bolt strength or thread shear limits

* The 2nd left block provides the joint preload (or clamping force)

* The remaining blocks list the max JOINT force for each failure mode

SUBSEQUENT JOINT LOADING IN SERVICE * The joint will either unseat first, or bolt will yield first ...use lower value

* bolt tension increases & joint compression decreases * For other cases, copy to a new sheet and edit the materials table

* To alter the (L/D) ratios, try changing columns C & I, or H & D

...bolt force

...member or joint force

COMPRESSIVE GRIP YIELDING UNDER THE HEAD

* Head bearing stresses (or face compression)

TAPPED THREAD FAILURE IN SHEAR

* local stresses include shear, bending, & contact loads

G (inlb) ~ 0.2 d Fi

Sb = Fb / At ...At = Tensile stress area (from tables)

* bolt tension (Fb) to Applied Joint Load (Pmax) relation

Fb = Fi + C Pmax

Fm = Fi + (C-1) Pmax

where: C = Kb / (Kb + Km ) ...the joint stiffness fraction

bolt stiffness: Kb = Eb (pd²/4) / L

joint stiffness: Km ~ Em (5p/16) (d+L/4) ²

* Bolt Yielding: Fb -> SyAt

* Joint Unseating: Fm -> 0

Fb = Shd (p/4) (D²hd -OD²)

* theoretical shear: ~ Ssy exp(-kz/L) …which is changed by local plasticity

* we might estimate shear profile as a trapeziod: ~ Ssy (1-k'z/L)

however, this is usually simplified to a triangle: Fthd ~ Ssy p OD (L/2)

* handbooks list tensile yield, so Ssy ~ 0.58 Sy (von Mises)

* In pullout test of ductile threads, we use: Ssut = f(Z/L) ...constant Ssut

but std thread form has p/8 flats, so : Fthd ~ Ssut p OD (7 Lthd /8)

Page 6: Bolt Design

Math

Page 6

* The intent was to automate the joint analysis details,

so the user can "what if" pick the % of yield for the bolt and thread

* The tab labels indicate: bolt mat'l, grip mat'l, and thread mat'l

* The left block provides the bolt installation torque

* This torque is the lower of bolt strength or thread shear limits

* The 2nd left block provides the joint preload (or clamping force)

* The remaining blocks list the max JOINT force for each failure mode

* The joint will either unseat first, or bolt will yield first ...use lower value

* For other cases, copy to a new sheet and edit the materials table

* To alter the (L/D) ratios, try changing columns C & I, or H & D

Page 7: Bolt Design

A286-Al

Page 7

pick PRELOADS: 73% of BOLT YIELD Strength for JOINT SHEAR:

73% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb)

0-80 2.0 1.7 2.0 171 144 171 320 347 164 124 96

2-56 6.0 5.1 6.0 351 295 351 657 713 337 256 198

4-40 12.8 11.2 12.8 573 501 573 1115 1164 517 418 336

6-32 24 21 24 863 760 863 1692 1752 765 628 510

8-32 44 35 44 1329 1073 1329 2390 2699 1355 968 720

10-32 72 55 72 1898 1441 1898 3208 3855 2104 1383 967

1/4-20 151 125 151 3018 2494 3018 5554 6130 2976 2199 1674

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N)

M2x0.4 0.54 0.44 0.54 1353 1100 1353 2449 2749 1369 986 738

M2.5x0.45 1.11 0.86 1.11 2217 1718 2217 3827 4502 2392 1615 1154

M3x0.5 1.97 1.48 1.97 3289 2474 3289 5511 6680 3686 2396 1661

M4x0.7 4.59 3.52 4.59 5741 4399 5741 9797 11660 6289 4183 2953

M5x0.8 9.28 6.87 9.16 9285 6874 9165 15308 18615 10609 7001 4614

M6x1.0 15.77 11.88 15.77 13143 9898 13143 22044 26694 14711 9575 6644

M8x1.25 38.29 28.15 37.54 23931 17596 23462 39189 47653 27562 18361 11812

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials

A-286 6061-T66061-T6 3xx SS Ti6Al4V

E (psi) 29E+06 10E+06 10E+06 29E+06 16E+06

E (Pa) 20E+10 07E+10 07E+10 20E+10 11E+10

160000 45000 45000 80000 150000

11E+08 03E+08 03E+08 06E+08 10E+08

130000 40000 40000 50000 140000

09E+08 03E+08 03E+08 03E+08 10E+08

note: gsfc uses 75% Sut for Bolt proof

JSmax =

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-

Fb = pSsy

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 8: Bolt Design

A286-Al

Page 8

APPLIED DESIGN (joint) LOADS Socket Head Screws

..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0

2.0 1.5 2.0 LIMIT CASE

(lb) (lb) (lb) (lb) (lb) OD(in) At (in²)

180 78 31 78 31 0.55 0.51 0.06 0.098 ###

370 160 64 160 64 0.55 0.51 0.086 0.140 ###

672 286 167 286 167 0.55 0.51 0.112 0.183 ###

1035 447 283 447 283 0.55 0.51 0.138 0.226 ###

1244 675 230 675 230 0.55 0.51 0.164 0.270 ###

1444 877 51 877 51 0.55 0.51 0.19 0.312 ###

3029 -72 -1110 -72 -1110 0.55 0.51 0.25 0.375 ###

APPLIED DESIGN (joint) LOADS Socket Head Screws

..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0

2.0 1.5 2.0 LIMIT CASE

(N) (N) (N) (N) (N) OD(m) At (m²)

1291 2105 1785 738 986 0.55 0.51 0.002 0.0038 ###

1816 3290 2589 1154 1615 0.55 0.51 0.003 0.0048 ###

2424 3857 2582 1661 2396 0.55 0.51 0.003 0.0055 ###

4519 4980 2762 2953 2762 0.55 0.51 0.004 0.0070 ###

6677 6087 2094 4614 2094 0.55 0.51 0.005 0.0085 ###

9723 7178 1400 6644 1400 0.55 0.51 0.006 0.0100 ###

17093 9313 -1446 9313 -1446 0.55 0.51 0.008 0.0130 ###

note: consider thick washers to improve joint crush

JSmax = m Fi m ~ 0.3 (unlubricated joint)

(C) joint K ratio bolt data ...DON"T change

Dshd (in)

P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

(C) joint K ratio bolt data ...DON"T change

Dshd(mm)

Page 9: Bolt Design

sh3xx-Al

Page 9

pick PRELOADS: 73% of BOLT YIELD Strength for JOINT SHEAR:

73% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.0 1.5 1.0 1.5

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb)

0-80 0.8 0.8 0.8 66 66 66 163 146 41 44 219

2-56 2.3 2.3 2.3 135 135 135 336 301 84 91 451

4-40 4.9 4.9 4.9 220 220 220 548 491 136 148 779

6-32 9 9 9 332 332 332 824 739 205 223 1187

8-32 17 17 17 511 511 511 1270 1138 316 343 1605

10-32 28 28 28 730 730 730 1814 1626 452 490 2081

1/4-20 58 58 58 1161 1161 1161 2884 2585 718 779 3775

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.0 1.5 1.0 1.5

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N)

M2x0.4 0.21 0.21 0.21 521 521 521 1294 1159 322 349 1650

M2.5x0.45 0.43 0.43 0.43 853 853 853 2118 1899 528 572 2513

M3x0.5 0.76 0.76 0.76 1265 1265 1265 3143 2817 783 849 3556

M4x0.7 1.77 1.77 1.77 2208 2208 2208 5487 4918 1367 1482 6390

M5x0.8 3.57 3.57 3.57 3571 3571 3571 8873 7953 2210 2397 9781

M6x1.0 6.07 6.07 6.07 5055 5055 5055 12560 11258 3129 3393 14231

M8x1.25 14.73 14.73 14.73 9204 9204 9204 22871 20499 5697 6179 24935

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials

3xx SS 6061-T66061-T6 3xx SS Ti6Al4V

E (psi) 29E+06 10E+06 10E+06 29E+06 16E+06

E (Pa) 20E+10 07E+10 07E+10 20E+10 11E+10

80000 45000 45000 80000 150000

06E+08 03E+08 03E+08 06E+08 10E+08

50000 40000 40000 50000 140000

03E+08 03E+08 03E+08 03E+08 10E+08

JSmax =

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-

Fb = pSsy

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 10: Bolt Design

sh3xx-Al

Page 10

APPLIED DESIGN (joint) LOADS Socket Head Screws

..SHEAR thread ..CRUSH grip

1.0 1.5 1.0 1.5

2.0 1.5 2.0 LIMIT CASE

(lb) (lb) (lb) (lb) (lb) OD(in) At (in²)

357 202 219 41 44 0.60 0.55 0.06 0.098 ###

733 416 451 84 91 0.60 0.55 0.086 0.140 ###

1259 732 794 136 148 0.60 0.55 0.112 0.183 ###

1917 1129 1224 205 223 0.60 0.55 0.138 0.226 ###

2630 1563 1696 316 343 0.60 0.55 0.164 0.270 ###

3450 1998 2167 452 490 0.60 0.55 0.19 0.312 ###

6161 2165 2348 718 779 0.60 0.55 0.25 0.375 ###

APPLIED DESIGN (joint) LOADS Socket Head Screws

..SHEAR thread ..CRUSH grip

1.0 1.5 1.0 1.5

2.0 1.5 2.0 LIMIT CASE

(N) (N) (N) (N) (N) OD(m) At (m²)

2701 2911 3157 322 349 0.60 0.55 0.002 0.0038 ###

4149 4482 4861 528 572 0.60 0.55 0.003 0.0048 ###

5907 5581 6052 783 849 0.60 0.55 0.003 0.0055 ###

10575 8259 8957 1367 1482 0.60 0.55 0.004 0.0070 ###

16304 11140 12081 2210 2397 0.60 0.55 0.005 0.0085 ###

23637 14724 15968 3129 3393 0.60 0.55 0.006 0.0100 ###

41625 22631 24544 5697 6179 0.60 0.55 0.008 0.0130 ###

JSmax = m Fi m ~ 0.3 (unlubricated joint)

(C) joint K ratio bolt data ...DON"T change

Dshd (in)

P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

(C) joint K ratio bolt data ...DON"T change

Dshd(mm)

Page 11: Bolt Design

ph3xx-Al

Page 11

pick PRELOADS: 73% of BOLT YIELD Strength for JOINT SHEAR:

73% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.0 1.5 1.0 1.5

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb)

0-80 0.8 0.8 0.8 66 66 66 163 146 41 44 219

2-56 2.3 2.3 2.3 135 135 135 336 301 84 91 451

4-40 4.9 4.9 4.9 220 220 220 548 491 136 148 779

6-32 9 9 9 332 332 332 824 739 205 223 1187

8-32 17 17 17 511 511 511 1270 1138 316 343 1605

10-32 28 28 28 730 730 730 1814 1626 452 490 2081

1/4-20 58 58 58 1161 1161 1161 2884 2585 718 779 3775

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.0 1.5 1.0 1.5

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N)

M2x0.4 0.21 0.21 0.21 521 521 521 1294 1159 322 349 1650

M2.5x0.45 0.43 0.43 0.43 853 853 853 2118 1899 528 572 2513

M3x0.5 0.76 0.76 0.76 1265 1265 1265 3143 2817 783 849 3556

M4x0.7 1.77 1.77 1.77 2208 2208 2208 5487 4918 1367 1482 6390

M5x0.8 3.57 3.57 3.57 3571 3571 3571 8873 7953 2210 2397 9781

M6x1.0 6.07 6.07 6.07 5055 5055 5055 12560 11258 3129 3393 14231

M8x1.25 14.73 14.73 14.73 9204 9204 9204 22871 20499 5697 6179 24935

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials

3xx SS 6061-T66061-T6 3xx SS Ti6Al4V

E (psi) 29E+06 10E+06 10E+06 29E+06 16E+06

E (Pa) 20E+10 07E+10 07E+10 20E+10 11E+10

80000 45000 45000 80000 150000

06E+08 03E+08 03E+08 06E+08 10E+08

50000 40000 40000 50000 140000

03E+08 03E+08 03E+08 03E+08 10E+08

note: gsfc uses 75% Sut for Bolt proof

JSmax =

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-

Fb = pSsy

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 12: Bolt Design

ph3xx-Al

Page 12

APPLIED DESIGN (joint) LOADS Pan Head Screws

..SHEAR thread ..CRUSH grip

1.0 1.5 1.0 1.5

2.0 1.5 2.0 LIMIT CASE

(lb) (lb) (lb) (lb) (lb) OD(in) At (in²)

357 408 443 41 44 0.60 0.55 0.06 0.116 ###

733 851 923 84 91 0.60 0.55 0.086 0.167 ###

1259 1493 1619 136 148 0.60 0.55 0.112 0.219 ###

1917 2276 2469 205 223 0.60 0.55 0.138 0.270 ###

2630 3182 3451 316 343 0.60 0.55 0.164 0.322 ###

3450 4195 4550 452 490 0.60 0.55 0.19 0.373 ###

6161 7498 8132 718 779 0.60 0.55 0.25 0.492 ###

APPLIED DESIGN (joint) LOADS Pan Head Screws

..SHEAR thread ..CRUSH grip

1.0 1.5 1.0 1.5

2.0 1.5 2.0 LIMIT CASE

(N) (N) (N) (N) (N) OD(m) At (m²)

2701 3476 3769 322 349 0.60 0.55 0.002 0.0040 ###

4149 5365 5819 528 572 0.60 0.55 0.003 0.0050 ###

5907 5983 6488 783 849 0.60 0.55 0.003 0.0056 ###

10575 13692 14849 1367 1482 0.60 0.55 0.004 0.0080 ###

16304 17660 19152 2210 2397 0.60 0.55 0.005 0.0095 ###

23637 30662 33254 3129 3393 0.60 0.55 0.006 0.0120 ###

41625 54146 58722 5697 6179 0.60 0.55 0.008 0.0160 ###

JSmax = m Fi m ~ 0.3 (unlubricated joint)

(C) joint K ratio bolt data ...DON"T change

Dpan (in)

P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

(C) joint K ratio bolt data ...DON"T change

Dpan(mm)

Page 13: Bolt Design

3xx-pcb-AL

Page 13

pick PRELOADS: 52% of BOLT YIELD Strength for JOINT SHEAR:

73% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.0 1.5 1.0 1.5

BOLT 1.0 1.5 BOLT 1.0 1.5 [smaller value ..unseat or yield first?] 1.0

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb)

0-80 0.6 0.6 0.6 47 47 47 1437 1195 45 45 87

2-56 1.7 1.7 1.7 96 96 96 2953 2457 92 92 179

4-40 3.5 3.5 3.5 157 157 157 4820 4011 150 151 310

6-32 7 7 7 236 236 236 7255 6037 226 227 473

8-32 12 12 12 364 364 364 11173 9297 347 350 637

10-32 20 20 20 520 520 520 15962 13282 496 500 822

1/4-20 41 41 41 827 827 827 25379 21118 789 794 1500

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.0 1.5 1.0 1.5

BOLT 1.0 1.5 BOLT 1.0 1.5 [smaller value ..unseat or yield first?] 1.0

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N)

M2x0.4 0.15 0.15 0.15 371 371 371 11383 9472 354 356 655

M2.5x0.45 0.30 0.30 0.30 607 607 607 18641 15511 579 583 994

M3x0.5 0.54 0.54 0.54 901 901 901 27659 23015 860 866 1404

M4x0.7 1.26 1.26 1.26 1573 1573 1573 48280 40174 1501 1511 2527

M5x0.8 2.54 2.54 2.54 2544 2544 2544 78084 64974 2427 2444 3859

M6x1.0 4.32 4.32 4.32 3601 3601 3601 ### 91970 3436 3459 5622

M8x1.25 10.49 10.49 10.49 6557 6557 6557 ### ### 6256 6299 9834

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials

3xx SS G-10 6061-T6 3xx SS Ti6Al4V

E (psi) 29E+06 50E+04 10E+06 29E+06 16E+06

E (Pa) 20E+10 34E+08 07E+10 20E+10 11E+10

80000 20000 45000 80000 150000

06E+08 01E+08 03E+08 06E+08 10E+08

50000 12000 40000 50000 140000

03E+08 83E+06 03E+08 03E+08 10E+08

JSmax =

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-

Fb = pSsy

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 14: Bolt Design

3xx-pcb-AL

Page 14

APPLIED DESIGN (joint) LOADS Pan Head Screws

..SHEAR thread ..CRUSH grip

1.0 1.5 1.0 1.5

1.5 1.0 1.5 LIMIT CASE

(lb) (lb) (lb) (lb) (lb) OD(in) At (in²)

156 48 48 45 45 0.97 0.96 0.06 0.116 ###

321 100 101 92 92 0.97 0.96 0.086 0.167 ###

550 183 184 150 151 0.97 0.96 0.112 0.219 ###

837 280 282 226 227 0.97 0.96 0.138 0.270 ###

1151 372 374 347 350 0.97 0.96 0.164 0.322 ###

1513 466 469 466 469 0.97 0.96 0.19 0.373 ###

2695 895 901 789 794 0.97 0.96 0.25 0.492 ###

APPLIED DESIGN (joint) LOADS Pan Head Screws

..SHEAR thread ..CRUSH grip

1.0 1.5 1.0 1.5

1.5 1.0 1.5 LIMIT CASE

(N) (N) (N) (N) (N) OD(m) At (m²)

1182 422 425 354 356 0.97 0.96 0.002 0.0040 ###

1818 631 635 579 583 0.97 0.96 0.003 0.0050 ###

2590 569 573 569 573 0.97 0.96 0.003 0.0056 ###

4635 1596 1607 1501 1511 0.97 0.96 0.004 0.0080 ###

7152 1750 1762 1750 1762 0.97 0.96 0.005 0.0095 ###

10364 3527 3551 3436 3459 0.97 0.96 0.006 0.0120 ###

18263 6110 6152 6110 6152 0.97 0.96 0.008 0.0160 ###

note: the Binding Head is a little better for PCB's

0.126

0.181

0.235

0.290

0.344

0.399

0.525

JSmax = m Fi m ~ 0.3 (unlubricated joint)

(C) joint K ratio bolt data ...DON"T change

Dpan (in)

P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

(C) joint K ratio bolt data ...DON"T change

Dpan(mm)

Dbind(in)

Page 15: Bolt Design

A286-Al-Ti

Page 15

pick PRELOADS: 73% of BOLT YIELD Strength for JOINT SHEAR:

73% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS Socket Head Screws

..Unseat JOINT ..YIELD BOLT ..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0 1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5 2.0 1.5 2.0 LIMIT CASE

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) OD(in) At (in²)

0-80 2.0 2.0 2.0 171 171 171 380 347 115 124 940 1473 29 31 29 31 0.55 0.51 0.06 0.098 ###

2-56 6.0 6.0 6.0 351 351 351 782 713 236 256 1931 3025 59 64 59 64 0.55 0.51 0.086 0.140 ###

4-40 12.8 12.8 12.8 573 573 573 1277 1164 385 418 3315 5174 154 167 154 167 0.55 0.51 0.112 0.183 ###

6-32 24 24 24 863 863 863 1921 1752 579 628 5047 7870 261 283 261 283 0.55 0.51 0.138 0.226 ###

8-32 44 44 44 1329 1329 1329 2959 2699 892 968 6928 10898 212 230 212 230 0.55 0.51 0.164 0.270 ###

10-32 72 72 72 1898 1898 1898 4227 3855 1274 1383 9091 14401 47 51 47 51 0.55 0.51 0.19 0.312 ###

1/4-20 151 151 151 3018 3018 3018 6721 6130 2026 2199 16225 25462 -1023 -1110 -1023 -1110 0.55 0.51 0.25 0.375 ###

APPLIED DESIGN (joint) LOADS Socket Head Screws

..Unseat JOINT ..YIELD BOLT ..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0 1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5 2.0 1.5 2.0 LIMIT CASE

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) OD(m) At (m²)

M2x0.4 0.54 0.54 0.54 1353 1353 1353 3014 2749 909 986 7113 11183 1645 1785 909 986 0.55 0.51 0.002 0.0038 ###

M2.5x0.45 1.11 1.11 1.11 2217 2217 2217 4937 4502 1488 1615 10930 17273 2385 2589 1488 1615 0.55 0.51 0.003 0.0048 ###

M3x0.5 1.97 1.97 1.97 3289 3289 3289 7325 6680 2208 2396 15563 24681 2379 2582 2208 2396 0.55 0.51 0.003 0.0055 ###

M4x0.7 4.59 4.59 4.59 5741 5741 5741 12786 11660 3854 4183 27860 44087 2545 2762 2545 2762 0.55 0.51 0.004 0.0070 ###

M5x0.8 9.28 9.28 9.28 9285 9285 9285 20678 18859 6233 6765 42960 68266 1711 1857 1711 1857 0.55 0.51 0.005 0.0085 ###

M6x1.0 15.77 15.77 15.77 13143 13143 13143 29270 26694 8822 9575 62276 98751 1290 1400 1290 1400 0.55 0.51 0.006 0.0100 ###

M8x1.25 38.29 38.29 38.29 23931 23931 23931 53298 48607 16064 17436 109684 174441 -2184 -2371 -2184 -2371 0.55 0.51 0.008 0.0130 ###

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials note: consider thick washers to improve joint crush

A-286 6061-T6Ti6Al4V 3xx SS Ti6Al4V

E (psi) 29E+06 10E+06 16E+06 29E+06 16E+06

E (Pa) 20E+10 07E+10 11E+10 20E+10 11E+10

160000 45000 150000 80000 150000

11E+08 03E+08 10E+08 06E+08 10E+08

130000 40000 140000 50000 140000

09E+08 03E+08 10E+08 03E+08 10E+08

JSmax = m Fi m ~ 0.3 (unlubricated joint)

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread (C) joint K ratio bolt data ...DON"T change

Dshd (in)

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread (C) joint K ratio bolt data ...DON"T change

Dshd(mm)

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 16: Bolt Design

A286-Al-Ti

Page 16

At (in²)

At (m²)

note: consider thick washers to improve joint crush

...DON"T change

...DON"T change

Page 17: Bolt Design

A286-Ti-Al

Page 17

pick PRELOADS: 85% of BOLT YIELD Strength for JOINT SHEAR:

73% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS Socket Head Screws

..Unseat JOINT ..YIELD BOLT ..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0 1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5 2.0 1.5 2.0 LIMIT CASE

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) OD(in) At (in²)

0-80 2.4 1.7 2.3 199 144 192 254 315 208 108 122 181 1174 1178 122 108 0.43 0.39 0.06 0.098 1.80E-3

2-56 7.0 5.1 6.8 409 295 394 521 647 428 223 251 371 2412 2420 251 223 0.43 0.39 0.086 0.140 3.70E-3

4-40 15.0 11.2 15.0 667 501 667 884 1098 656 301 427 630 4153 4174 427 301 0.43 0.39 0.112 0.183 6.04E-3

6-32 28 21 28 1004 760 1004 1343 1652 972 452 648 979 6364 6424 648 452 0.43 0.39 0.138 0.226 9.09E-3

8-32 51 35 47 1547 1073 1431 1896 2353 1720 993 915 1351 9181 9256 915 993 0.43 0.39 0.164 0.270 1.40E-2

10-32 84 55 73 2210 1441 1921 2545 3159 2671 1733 1228 1813 12196 12282 1228 1733 0.43 0.39 0.19 0.312 2.00E-2

1/4-20 176 125 166 3514 2494 3325 4407 5468 3778 2063 2125 3138 14045 13435 2125 2063 0.43 0.39 0.25 0.375 3.18E-2

APPLIED DESIGN (joint) LOADS Socket Head Screws

..Unseat JOINT ..YIELD BOLT ..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0 1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5 2.0 1.5 2.0 LIMIT CASE

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) (N) OD(m) At (m²)

M2x0.4 0.63 0.44 0.59 1576 1100 1466 1943 2411 1738 989 937 1384 15688 16441 937 989 0.43 0.39 0.002 0.0038 2.07E-6

M2.5x0.45 1.29 0.86 1.15 2581 1718 2291 3036 3768 3037 1902 1464 2162 24513 25688 1464 1902 0.43 0.39 0.003 0.0048 3.39E-6

M3x0.5 2.30 1.48 1.98 3830 2474 3299 4372 5426 4679 3078 2109 3114 31389 32661 2109 3078 0.43 0.39 0.003 0.0055 5.03E-6

M4x0.7 5.35 3.52 4.69 6685 4399 5865 7773 9645 7983 5100 3749 5536 47464 48828 3749 5100 0.43 0.39 0.004 0.0070 8.78E-6

M5x0.8 10.81 6.87 9.16 10811 6874 9165 12145 15071 13467 9069 5857 8650 66635 67957 5857 8650 0.43 0.39 0.005 0.0085 1.42E-5

M6x1.0 18.36 11.88 15.84 15303 9898 13197 17489 21702 18674 12264 8434 12455 88902 90047 8434 12264 0.43 0.39 0.006 0.0100 2.01E-5

M8x1.25 44.58 28.15 37.54 27865 17596 23462 31092 38582 34987 23784 14994 22143 142728 143115 14994 22143 0.43 0.39 0.008 0.0130 3.66E-5

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials

A-286 Ti6Al4V 6061-T6 3xx SS Ti6Al4V MY TEST CASE failure failure failure

E (psi) 29E+06 16E+06 10E+06 29E+06 16E+06 test result 8-32 sh (L/D) torque preloa stress

E (Pa) 20E+10 11E+10 07E+10 20E+10 11E+10 thread shear 1/8" pla 0.76 48 1463 44774 45 ksi

160000 150000 45000 80000 150000 broke head 1/4" pla 1.52 78 2378 ### min 160 ksi

11E+08 10E+08 03E+08 06E+08 10E+08

130000 140000 40000 50000 140000

09E+08 10E+08 03E+08 03E+08 10E+08

JSmax = m Fi m ~ 0.3 (unlubricated joint)

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread (C) joint K ratio bolt data ...DON"T change

Dshd (in)

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread (C) joint K ratio bolt data ...DON"T change

Dshd(mm)

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 18: Bolt Design

Al Inserts

Page 18

pick PRELOADS: 73% of BOLT YIELD Strength for JOINT SHEAR:

70% of Tapped Thread SHEAR YIELD Strength

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ANSI size (in lb) (in lb) (in lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb) (lb)

2-56 6.0 3.3 4.4 351 190 253 336 417 670 581 362

4-40 12.8 7.3 9.7 573 324 432 572 710 1063 901 625

6-32 24 14 18 863 493 658 872 1082 1586 1336 958

8-32 44 22 30 1329 675 901 1193 1481 2637 2346 1223

10-32 72 35 47 1898 931 1242 1646 2042 3844 3466 1791

1/4-20 151 78 104 3018 1557 2076 2751 3414 5937 5252 2767

APPLIED DESIGN (joint) LOADS

..Unseat JOINT ..YIELD BOLT ..SHEAR thread

1.5 2.0 1.5 2.0

BOLT 1.5 2.0 BOLT 1.5 2.0 [smaller value ..unseat or yield first?] 1.5

ISO Size (Nm) (Nm) (Nm) (N) (N) (N) (N) (N) (N) (N) (N)

M2x0.4 0.54 0.44 0.54 1353 1107 1353 1957 2226 1721 1277 4738

M3x0.5 1.97 1.25 1.66 3289 2076 2768 3669 4552 5597 4433 6605

M4x0.7 4.59 2.66 3.54 5741 3322 4429 5870 7284 10465 8765 8747

M5x0.8 9.28 4.84 6.46 9285 4844 6459 8560 10622 18142 15973 11161

M6x1.0 15.77 7.97 10.63 13143 6644 8858 11739 14567 26172 23336 13849

M8x1.25 38.29 17.72 23.62 23931 11073 14764 19565 24279 50016 45979 20044

note: 4 Nm = 35.433 in lb

MATERIALSBOLT GRIP Thread ...other materials

A-286 Ti6Al4V 5083-0 Al 3xx SS Ti6Al4V

E (psi) 29E+06 16E+06 10E+06 29E+06 16E+06

E (Pa) 20E+10 11E+10 07E+10 20E+10 11E+10

160000 150000 42000 80000 150000

11E+08 10E+08 03E+08 06E+08 10E+08

130000 140000 21000 50000 140000

09E+08 10E+08 01E+08 03E+08 10E+08

JSmax =

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

G (inlb) ~ 0.2 d Fi %SyAt %Ssy p od L/2 Fm = 0 = Fi(1-C) Fb = (SyAt-Fi)/C P = (Fb-

Fb = pSsy

TORQUE (G) Joint PRELOAD (Fi)

% Sb % thread Ssy % Sb % thread Ssy

(L/D)grip

(L/D)thread

Stensile(psi)

Stensile(Pa)

Syield (psi)

Syield (Pa)

Page 19: Bolt Design

Al Inserts

Page 19

APPLIED DESIGN (joint) LOADS Socket Head Screws & Helicoils

..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0 thread

2.0 1.5 2.0 LIMIT CASE Insert

(lb) (lb) (lb) (lb) (lb) OD(in) At (in²) OD(m)

535 2654 2778 336 417 0.43 0.39 0.086 0.140 ### 0.110

922 4559 4774 572 710 0.43 0.39 0.112 0.183 ### 0.144

1415 6978 7309 872 1082 0.43 0.39 0.138 0.226 ### 0.178

1805 10098 10610 1193 1481 0.43 0.39 0.164 0.270 ### 0.205

2645 13369 14015 1646 2042 0.43 0.39 0.19 0.312 ### 0.244

4086 16204 16623 2751 3414 0.43 0.39 0.25 0.375 ### 0.310

APPLIED DESIGN (joint) LOADS Socket Head Screws

..SHEAR thread ..CRUSH grip

1.5 2.0 1.5 2.0 thread

2.0 1.5 2.0 LIMIT CASE Insert

(N) (N) (N) (N) (N) OD(m) At (m²) OD(m)

7310 15671 16729 1721 1277 0.43 0.39 0.002 0.0038 ### 0.004

9755 32307 34016 3669 4433 0.43 0.39 0.003 0.0055 ### 0.005

12917 49945 52493 5870 7284 0.43 0.39 0.004 0.0070 ### 0.006

16482 71310 74860 8560 ### 0.43 0.39 0.005 0.0085 ### 0.007

20451 96400 ### ### ### 0.43 0.39 0.006 0.0100 ### 0.008

29601 ### ### ### ### 0.43 0.39 0.008 0.0130 ### 0.010

JSmax = m Fi m ~ 0.3 (unlubricated joint)

(C) joint K ratio bolt data ...DON"T change

Dshd (in)

P = (Fb-Fi) /C P = (Fb-Fi) /C

Fb = pSsyDL/2 Fb = pSy(D²-d²) /4

(C) joint K ratio bolt data ...DON"T change

Dshd(mm)