-
NASA
Technical Memorandum
100281
Simplified
Composite
Procedures for Designing
Bolted Joints
INASA-TH-
100281)
SIBPLIFIBD
PBOCEDCJB
ES
POB
IJ88-15020
DESIGIJIIC
COnPOSITE
BOLTED
JOINTS
(NASA)
CSCL
11D
Uoclas
1s
P
G3/24
0119506
Christos
C.
Chamis
Lewis
Research
Center
Cleveland, Ohio
Prepared
for
the
43rd Annual Conference
of
the Society
of
the Plastics Industry
Cincinnati,
Ohio,
February
1-5,
1988
SIMPLIFIED
PROCEDURES
FOR
DESIGNING
COMPOSITE
BOLTED
JOINTS
I.
cu
cu
or
m
Christos
C.
Chamis
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio
44135
SUMMARY
Simplified procedures (methods) are described
to
design/analyze single
and multibolt composite joints. Numerical examples illustrate the use
of
these methods. Factors affecting composite bolted joints are summarized.
References are cited where
more
detailed discussion are presented on specific
aspects
of
composite bolted joints.
joints are summarized in the appendix.
Design variables associated with these
INTRODUCTION
The structural integrity
of
composite structures
is
often times
determined by the
integrity and durability
of
their respective joints. The
two
general classes
of
joints are mechanical
fasteners and adhesive bonding.
The integrity
of
the mechanical fastener joints depends mainly on the local
laminate bearing strength, while that
for
adhesively bonded joints, depends
mainly on local interlaminar shear strength.
I
IW
Composite joints have been extensively investigated in recent years.
Results
of
these investigations are reported, in part, in symposium
proceedings (refs.
1
and
2).
Helpful recommendations
for
design practice
for
select composite joints are included in reference
3.
detailed
stress
calculations are described in reference
4.
Analysis methods
for
Recent research at the
NASA
Lewis Research Center focuses on developing
simplified methods
for
predicting microstresses and local
laminate strengths
including interlaminar strengths
(refs.
5
and
6).
In this report these
methods are used to design bolted
joints
for composite structures.
The
objective
of
the paper
is
to
describe these methods and outline a step-by-step
procedure
for
their use in the preliminary design phase
of
composite joints.
Several numerical examples are included
to
illustrate applications
of
these
simplified methods
to
select bolted composite joints. Typical design
variables are summarized in the appendix
for
convenience.
COMPOSITE
BOLTED JOINTS: FAILURE
MODES
AND
ANALYSIS
Bolted joints are designed
to
resist
certain select failure modes during
the preliminary design phase.
commonly occurring in practical applications. They include:
(1)
local
bearing,
(2)
net tension,
(3)
wedge-type splitting,
(4)
shear-out, and
(5)
tension with shear-out. These select failure modes and the approximate
equations used
to
quantify them are described below in detail.
These select failure modes are those
most
Local Bearing Fai
1
ure Modes
Local bearing failure modes are characterized by a local laminate
compressive failure caused by the bolt diameter which tends to crush the
composite material.
A
schematic
of
these types
of
failure modes is shown in
figure 1. The schematic which is used to derive the equation and the
respective equation are also shown in figure
1.
design against this failure mode are
:
(1)
bolt diameter (d),
(2)
laminate
thickness (t,), and
(3)
laminate compressive strength parallel to the bolt
force (ScxxC). Use
of
the equation (fig.
l(a>>
is illustrated in the
following example.'
The requisite variables to
Example
1.
Calculate the local average bearing stress
(acxx>
in
a
[O+45/O/901s
AS/E
laminate induced
by
a 1/4-in. diameter titanium bolt with
a
1000
lb load. These referred to herein as the composite bolted joint
specified conditions. To perform this calculation, we first solve the
equation in figure l(a> for
Scxxc
and replace
S
with
u
F
--
U
-
cxx dtc
where
F
is
1000
lb, d is
1/4
in., and tc is
0.05
in.
(10
piles at
0.005in.lply). Using these
values in the equation we obtain
=
80
000
psi
-
1000
lb
cxx
-
(0.25
by
0.05)
U
The corresponding laminate compressive strength
(Scxxc)
from table
I
is
79
700
psi. The margin-of-safety (MOS) against local bearing failure is
Therefore, this bolted connection will barely fail in local bearing.
Net Tension Failure Modes
Tensile failure modes are characterized by "net-tension" laminate
fracture.
A
schematic
of
these types
of
failure modes is shown in figure lb
where the schematic used to derive the governing equation and the equation are
also shown.
(1)
net section width (w
-
d),
(2)
laminate thickness (tc> and
(3)
laminate
tensile strength
(Scxx~>.
Use
of
the equation (fig. lb) is illustrated in the
fol
lowi ng example.
The requisite variables to design against this failure mode are:
Example
2.
the composite bolted joint specified conditions in example
1
with bolt spacing
(w) equal 1.0
in.
To
perform this calculation we solve the equation in figure
lb for
Scxx~.
F
Calculate the net section stress
(ucXx)
at the bolt hole edge for
where
F
is
1000
lb/in., w is
1.0
in.,
d
is 114 in., and tc
=
0.05
in.
Using these values in the equation we obtain
2
=
26
700
psi
-
1000
lb
cxx
-
r(1.00
in.
-
0.25
in.)
x
0.05
in.]
0
The corresponding laminate tensile strength
(Scxx~>
from
table
I
is
79
200
psi. The margin
of
safety
is
79
2oo
si
-
1
=
1.97
0.K.
Therefore this composite bolted joint
will
not fail in net tension.
Wedge-Type Splitting Failure Modes
Wedge-type splitting failure modes in composite bolt joints are
characterized by laminate splitting which starts at the local bearing point
and propagates
to
the
free
edge. These failure modes are caused by the
lateral pressure
of
the bolt against the laminate. The failure mode
is
shown
in figure l(c) where the schematic used
to
derive the equation and the
equation are also shown.
failure mode are:
(1)
bolt diameter (d),
(2)
laminate the thickness
(tc)
(2)
edge distance (e) and
(3)
laminate transverse tensile strength
(Scyy~).
following example illustrates use
of
the equation in figure l(c).
The requisite variables
to
design against this
The
Example
3.
Calculate the transverse splitting stress
(ucYy)
for
the
composite bolted joint specified conditions in example
1
with
e
equal
to
1.0
in.
To
perform this calculation
we
solve
the equation in figure l(c)
for
Scyy~
and replace
S
with
o
2F
- -
cyy
C(2e
-
d)t,l
0
where
F
is
1000
lb,
e
=
1.0 in.,
d
is
114 in. and
tc
is
0.05
in. Using
these
values
in
the equation
we
obtain
=
22
860
psi
-
2
x
1000
lb
cyy
-
C(2
x
1.00 in.
-
0.25
in.)(0.05 in.)]
0
The corresponding strength from table
I
is
49
800
psi. The margin
of
safety
is
49
8oo
-
1
=
1.18
O.K.
MoS
=
(22
860
psi)
Therefore, this composite bolted joint
will
not fail in wedge-type splitting.
Shear-Out Failure Modes
Shear-out failure modes in composite bolted joints are characterized by
shear-out part
of
the
laminate ahead of the bolt.
*4
schematic depicting this
3
failure mode is shown in figure
l(d1
where the schematic used to derive the
equation and the equation are also shown. The requisite variables to design
against shear-out are:
(1)
the edge distance (e),
(21
the laminate thickness
(tc> and
(31
the laminate shear strength
(Scxys).
illustrates one use
of
the equation in figure l(d>.
The following example
Example
4.
Calculate the shear-out stress for the composite bolted joint
specified conditions in Example
1
with an edge distance
of
1.0
in.
To
calculate the shear-out stress we first solve the equation in figure l(d1 for
Scxys
and replace
S
by
u
where
F
is
1000
lb, e is
1.0
in., and tc is
0.05
in. Substituting these
values in the equation we obtain
=
10
000
psi
-
1000
lb
cxy
-
(2
x
1.00
x
0.05
in.)
0
The corresponding in-plane strength from table
I
is
38
700
psi. The
margin-of-safety is
Therefore, this composite bolted joint will not
fail
by shear-out.
As
a
matter
of
fact, its edge distance can be decreased to
1/2
in. and still have
substantial MOS
(0.941.
Tension With Shear-otit Failure Modes
Tension with shear-out failure modes are characterized
by
part
net-section and part
shear.
A
schematic
of
the failure mode
is
shown in
figure l(e) where the schematic used to derive the equation and the equation
are also shown. The requisite variables to design against this failure mode
are:
(11
laminate thickness,
(2)
net section dimension
(w
-
d),
(3)
edge
distance (e),
(4)
laminate tensile strength
(Scxx~l,
and
(5)
laminate in-p
shear strength
(Sex
s).
The following example illustrates one use
of
the
equation in figure Y(e).
Example
5.
Calculate the margin
of
safety
of
the composite bolted
jo
specified in Example
1
with bolt spacing
1.0
in. and edge distance
1.0
in.
calculate the MOS for this examDle we first calculate the bolt load
(F1
to
ane
nt
To
cause laminate failure and than we compare this to the specified value
of
1000
lb. Repeating the equation:
tcUw
-
dlScxxT
+
2e
'cxyS1
2
F=
4
where
tc
is
0.05
in.,
w
is
1.0
in., d
is
114 in., e
is
1.0
in.,
Scxx~
is
79
200 psi (table
I>
and
Scxys
in the equation
is
38
700
psi (table
I).
Using these values
0.05
in.L(l.00 in.
-
0.25 in.>x79
200
psi
+
2
x
1.0
in.
x
38
700
psi1
=
3420
lb
2
F=
The corresponding specified load
is
1000
lb. The margin-of-safety
is
-
1
=
2.42
O.K.
3420 lb
MoS
=
1000
lb
Therefore, thi
s
composite bo1 ted joint
wi
11
not fai
1
by combined net-tension
and shear-out.
Taken collectively these calculations show that local bearing
is
the
most
likely failure mode
for
this composite bolted joint.
can obtain insight by repeating the previous exercises using the strengths
for
the other
two
laminate configurations in table
I.
The interested reader
MULTI-BOLT
COMPOSITE
JOINTS
Multi-bolt composite joints are required
to
transfer load between
two
adjacent panels
or
from
a panel
to
its
attachment.
A
representative schematic
is
shown in figure 2. Multi-bolt composite joints are designed by assuming
that all the bolts in the joint are sharing equal load. In reality, the
first
row
of
bolts
will
usually transfer more load. However, any insignificant
local bearing failure
will
redistribute the load
to
the next bolt
row
and
so
on.
The example below illustrates the design procedure.
Example
6.
Design a composite joint connecting a composite panel
to
a
metallic plate attachment. Refer
to
the schematic in figure 2. For this
joint
we
only
design the bolts
for
the composite panel. We assume that the
metallic attachment has adequate strength. The composite panel
is
made
from
[O/+45/9OIs
AS/E.
The panels carries 2000 lb/in. design tensile load and
is
0.05
in. thick. We
will
use 114 in. diameter bolts. The bolt spacing
is
6
bolt diameters (1.5 in.) and the edge distance
is
4 bolt diameters
(1.0
in.)
Step
1.
Determine the load carried per bolt. The load carried per bolt
is
the bolt spacing times the panel load per inch.
p
x
Ncxx
=
1.5
in.
x
2000
lb/in.
3000
lb
Step 2.
Determine the number
of
bolts per bolt
row.
Assuming first
bearing failure mode, the number
of
bolts
N
is
determined
from
figure l(a>:
F
N=
(d
tc scxxc)
5
where
F
is
3000
lb in.; d
=
114 in.; tc
is
0.050
in.; and
Scxxc
is
79
700
psi. Using this
values
in the equation we calculate
3000
lb/in.
N=
E(0.25
in.) (0.050 in.)
(79
700
lb/in.2)1
N
=
3.01
bolts, use
3
bolts
Check next net tension, the number
of
bolts in
N
is
from (fig. l(b>)
F
N=
[W
-
dlt, ScxxT
where
F
=
3000
lb,
w
is
1.50
in.; d
is
0.25
in.; tc
=
0.05
in.; and
Scxx~
is
79
200
lb/in.2.
Using these values in the equation
we
calculate
3000
lb
N=
L(1.5
in.
-
0.25
in.)
(0.050
in.
79
200
lb/in.2>3
N
=
0.61 bolts,
use
1
bolt
Therefore, local bearing
is
more severe than net tension.
Step
3.
Check the other
failure
modes
for
the edge and corner bolts.
First
Row
Center Bolt
in
Shear-Out
The shear stress
is
calculated from the equation (fig. l(d>>.
where
F
is
1000
lb;
e
is
1.0 in.; and t,
is
0.05
in. Using these
values
in the equation, we calculate
2
=
10
000
lb/in.
-
1000
lb
cxx
-
(2
x
1.0
in.
x
0.05
in.)
0
10
000
lb/in.2
<
38
700
lb/in.2
O.K.
and
2
2
-
1
=
2.87
38
700
lb/in.
10
000
lb/in.
MOS
=
First Row Center
Bolt
in Wedge-Type Splitting
The transverse
tensile
stress
from
the
equation
in
figure
l(c)
is:
3C
LI
-
U
-
cyy
[(2e
-
d)tcl
6
Substituting respective numerical values, we calculate
2
=
32
000
lb/in.
2
x
1000
lb
[(2
x
1.0
in.
-
0.25
in.)
x
0.05
in.]
32
000
lblin.2
<
49
800
lblin.2
cyy
=
O.K.
and
2
2
-
1
=
0.56
49
800
lb/in.
32
000
lb/in.
MOS
=
Corner Bolt in Tension with Shear-Out
The force required to induce tension with shear-out in the corner bolt is
calculated from (fig. l(e)> where
w
=
p
tc[(p
-
d)ScxxT
+
2e
Sc,
2
F=
Using respective numerical values in the equation, we calculate
F
=
0.05
in.L(l.50 in.
-
0.25
in.)
x
79
200
lb/in.2
+
2
x
1.00
in.
38
700
lb/in.21/2
=
4410
lb
4410
lb
>
1000
lb
O.K.
and
4410
lb
-
1
=
3.41
MoS
=
(1000
Ib)
Therefore, use three
1/4
in. bolts per column at
1.50
in. on centers to join
the composite panel to the metal attachment (fig.
2).
GENERAL
DISCUSSION
Several other factors influence composite bolted joint des gn. These
include
(1)
bypass load,
(2)
load transferred through friction,
(3)
cyclic
load,
(4)
temperature effects,
(5)
moisture effects,
(6)
biaxia loads,
(7)
flat-wise compression due to bolt torqueing, and
(8)
flat-wise oca1 bearing
at the edge
of
bolts heads, nuts, or washers.
A
brief discussion on each
of
these factors follow.
Bypass load.
-
The bypass load is that load that bypasses the bolt and
must be resisted by bolts following the bolt being bypassed.
important
in multi-bolted joints and was implied in the multi-bolted joint
This is
7
designed discussed previously. They key question
is
how much
of
the load
is
bypassed. This
is
not as simple a problem as
it
may seem. Usually innovative
use
of
finite element analysis
is
needed
to
determine the bypass load.
Load transferred through friction.
-
The load transferred through
friction reduces the load transferred through the bolt. This load can be
substantial.
It
depends on the through-the-thickness compressive stress and
the coefficient
of
friction between
(1)
bolt head, washer
or
nut and composite
and
(2)
between the composite panel surfaces
or
composite panel metallic
attachment surface. The load transferred through friction may not be
dependable in situations where there are temperature fluctuations and large
differences in the thermal expansion coefficients
of
the composite and the
bolt. The load transferred through friction increases the bearing load
capacity compared
to
that predicted using laminate compression strength in
general (ref.
7).
Cyclic load effects.
-
Cyclic load effects generally degrade the laminate
The degree
of
degradation depends on the number
of
cycles, cyclic
strengths.
stress range, mean stress, and environmental conditions. Procedures
for
estimating some
of
these strength degradations are described in reference
6.
The degraded strengths are used in the equations in figure
1
to
designlanalyze
the bolted joint.
Temperature effects.
-
The temperature effects influence the laminate
strengths. Procedures
for
evaluating this influence are described in
reference
6.
The modified strengths are used in the equations in figure
1
to
designlanalyze the bolted joint.
Moisture effects.
-
Moisture effects are handled the same way as
temperature effects. The combined moistureltemperature effects on laminate
strength are also estimated using the procedures in reference
6.
Biaxial loads.
-
In biaxial load cases
(for
example,
x
and
y
loads) the
bolted joint
is
designed
to
transfer both loads. The assumption made
is
that
each load
is
transferred independently. The equations in figure
1
are applied
individually
to
each
x
and
y
loads. Other effects are incorporated as was
described previously.
Flat-wise compression.
-
Flat-wise compression
is
induced by torqueing
the bolt
to
a predetermined value in order
to
prevent slippage between
panels.
compression required. Calibration experiments are generally conducted
to
develop flat-wise compression versus torque curves which are used
to
specify
the torque
to
be used. The torque can also be estimated
from
elementary
mechanics and energy balance concepts.
The amount
of
torque used
is
determined
from
the amount
of
flat-wise
Flat-wise load bearing at the edges
of
bolt-heads, nuts,
or
washers.
These are usually caused by
(1)
uneven joint,
(2)
local bending
-
prominent in
single lap joints, and
(3)
combinations. This stress value
is
determined by
knowing the
olt
torque, the amount
of
bending, and the environmental
conditions. Estimates are obtained using elementary mechanics concepts.
Accurate eva uations are determined by innovative use
of
finite element
analysi
s.
8
Many
of
the factors discussed previously have been investigated, in part,
and reported in the technical literature. For example the various failure
modes in composites are discussed extensively in reference
7.
The edge
distance effect on net tension failure and bearing stress have been
investigated and reported
in
reference
7.
The local stress distribution in
the periphery
of
the bolt hole due to different types
of
bolts is discussed in
reference
4
where the effect
of
clearance on the bearing (radial) and hoop
stress are also discussed. The fatigue effects on composite joints
is
discussed in reference
7.
The effects
of
(1)
bolt diameter to thickness ratio
(D/t>,
(2)
bolt spacing to diameter ratio, and
(3)
edge distance to bolt
diameter ratio are discussed in reference
3.
Recommended allowables for
select D/t ratios and for several composites are included in reference
3
where
recommended clearances, edge and side distances are also included.
Design
of
composite joints requires considerable care. The methods
described here are adequate for
the preliminary design phase only. These
methods must be complemented with appropriate finite element analyses and
strategic experiments for final design. The references cited provide a
variety
of
guidelines for selecting appropriate analyses and experiments.
SUMMARY
Simplified methods to designlanalyze composite bolted joints have been
presented. The typical failure modes are discussed and respective equations
to design for these failure modes are presented.
by applying them to single and multi-bolt composite joint designs. Various
factors affecting composite joint design are summarized. Select references
are cited where more extensive discussions on specific aspects
of
bolted
composite joints can be found. The methods and sample calculations presented
in this paper are suitable for the preliminary design phase. The methods need
to be complemented with appropriate finite element analyses and selective
testing for the final design phase.
The methods are illustrated
REFERENCES
1.
K.T. Kedward, Ed., Joining
of
Composite Materials, ASTM STP
749,
ASTM,
Philadelphia, PA, 1981.
2.
Jointing in Fiber Reinforced Plastics, IPC Science and Technology
Press Ltd., Surrey England,
1978.
3.
S.J.
Dasting, "Joining and Machining Technique," Handbook
of
Composites,
G.
Lubin,
Ed.,
Von Nostrand, New York,
1982,
Chapter
22.
4.
M.W. Hyer and E.C. Klang, "Contact Stresses in Pin-Loaded Orthotropic
Plates," Int.
J.
Solids Struct.,
vol.
21,
no.
9,
Sept.
1985,
pp. 957-975.
5.
P.L.N. Murthy and
C.C.
Chamis, "Integrated Composite Analyzer (ICAN)
Users and Programmers Manual," NASA TP-2515, 1986.
6.
C.C.
Chamis and C.A. Ginty, "Composite Structural Durability and Damage
Tolerance: Simplified Predictive Methods," NASA TM-100179, 1987.
9
7.
R.L. Ramkumar, and
E.W.
Tossavainen, "Strength and Lifetime
of
Bolted
Laminates," Fatigue in Mechanically Fastened Composite and Metallic
Joints, ASTM STP
927,
J.M.
Potter,
Ed.,
ASTM, Philadelphia,
1986,
pp. 251-273.
I
10
APPENDIX
DESIGN
VARIABLES
FOR
COMPOSITE
BOLTED
JOINTS
Laminate (composite) bolted connections are mainly controlled by
two
groups
of
design variables, those
for
the bolts and those
for
the laminates,
as
follows:
I.
Bolt
design variables
1.
Bolt
diameter (d>
2. Washer, bol't-head
or
nut diameter (dw>
3.
Bolt
material and threads per inch
4.
Bolt
strength (static, cyclic), tension and shear (single, double)
tensile yield strength (Sb
T>
for
bolt pretension
shear yield strength (sbyTJ
for
bolt pretension
oftentimes the bolt strengths are specified by the supplier
5. Thermal expansion coefficients
11.
Laminate design variables
1.
Laminate strengths (static, cyclic, environmental)
a. Bearing
-
axial compressive strength
(Scxxc)
b. Axial tensile strength
(Scxx~)
c.
Transverse tensile strength
(Sty
T)
d. Through-the thickness (flat-wisey compressive strength
(Sczz~)
for
local bearing due
to
bolt pretension and/or joint local bending
2. Laminate thickness
(tc)
-
multiples
of
basic laminate configurations
for
which the laminate strengths in
11-1
are known
3.
Laminate edge distances
a. Axial direction (e>
b. Transverse direction
(w
-
d>/2
c.
Bolt
spacing
(W)
or
pitch (p)
-
both width-wise
(row)
and
span-wise (column). The spacing can be square, rectangular,
or
staggered.
4.
Laminate moduli and
Posison's
ratios
5. Laminate thermal and moisture expansion coefficients
6.
Temperature and moisture effects on all properties
The laminate properties needed
for
bolted joint design are either
available
from
tests
or
can be predicted using the computer codes such
as
ICAN
(ref. 5) as were the properties in table
I.
111.
Safety factors
Safety factors are usually established
for
specific designs.
Two
cases
generally exist in the preliminary design phases
1.
Design loads given
-
for
this case no safety factors are required and
margins
of
safety
of
0.15
or
greater on failure modes are typically
acceptable.
2.
Specified
or
ultimate loads given
-
nominal factors
of
safety are:
(1)
2
for
loads
for
the composite and
(2)
1.5 on the yield stress
for
the bolts. Additional safety factors
may
be required
for
cyclic loads.
11
TABLE
I.
PREDICTED FRACTURE STRESSES
FOR
SELECT LAMINATESa
[AS/E AT
0.6
FVR.]
Stress
Laminate/fracture stress, ksi
[(0/+45/0/90)]s
I
[(03/f80)Is
I
[(0/+3-/0s/-30/0)1s
ScxxT
scxxc
CYYC
ScxyS
sczzs
79.2
79.7
49.8
51.5
30.7
21.8
94.8
99.1
61
.O
67.8
13.1
21.8
129.3
70.5
6.3
14.7
20.1
21.8
aPredicted using the ICAN computer code (ref.
5).
Notation:
SC
Laminate strength
x,y,z Direction (x,y
-
laminate plane;
z-
thickness
T,C,S Tension, compression, shear
I
F
LF
cxx
I
OCYY
Ocxy
rjfl
1
OcxypJ
COORDINATE
REFERENCE
AXES
pg
(a)
LOCAL BEARING.
(b)
NET TENSION.
(c)
WEDGE-TYPE (d) SHEAR-OUT.
(e)
TENSION
WITH
SPLITTING. SHEAR-OUT
.
AT FRACTURE:
BOLT FORCE F
=
(W
-
d)t,Scx,,
1
2etcScxys
-
tC
[tu
-
d)ScxxT
+
2e%xysl
dtcScxxc
-
2
(2e
-
d)tScyy,
2
FIGURE
1.
-
COMPOSITE BOLTED JOINTS
-
FAILURE MODES AND RESPECTIVE EQUATIONS.
r
BOLT
,’
r
WASHER
COMPOS
I
TE
PANEL
7
I
NCXX r-ETALLlC ATTACHMEN1
c-
-
NCXX
-
NUT
NOTAT ION
:
Ncxx IN-PLANE LOAD
p
BOLT SPACING (PITCH)
e
EDGE DISTANCE
[e
=
(p
-
d)/21
SQUARE ARRAY PATTERN
FIGURE
2.
-
SCHEMATIC OF MULTI-BOLT COMPOSITE JOINT.
13
Nalional
Aeionaulcs
and
1.
Report No.
NASA TM-100281
Report Documentation Page
2.
Government Accession No.
17
Key Words (Suggested by Author(s))
Fiber composites; Illustrative examples;
3esign; Analysis; Failure modes;
Bearings; Net tension; Splitting;
Shear-out; Combined; Composite strengths
Simplified Procedures for Designing
Composi te Bo1 ted
Joi
nts
18
Distribution Statement
Unclassified
-
Unlimited
Subject Category
24
7.
Author@)
Christos
C.
Chamis
9 Security Classif (of this report)
20
Security Classif (of this page)
21
No of pages
Unclassified Unclassified
14
~~
9.
Performing Organization Name and Address
National Aeronautics and Space Administration
Lewi
s
Research Center
C1
eve
1
and, Ohio
441
35-31
91
12.
Sponsoring Agency Name and Address
22
Price'
A02
National Aeronautics and Space Administration
Washington,
D.C.
20546-0001
15.
Supplementary Notes
Prepared for the 43rd Annual Conference
of
the Society
Cincinnati,
Ohio,
February
1-5,
1988.
3.
Recipient's Catalog No
5.
Report Date
6.
Performing Organization Code
8.
Performing Organization Report No.
E-3922
10.
Work Unit No.
505-63-1
1
11.
Contract or Grant No
13.
Type of Report and Period Covered
Technical Memorandum
14.
Sponsoring Agency Code
of
the Plastics Industry,
16.
Abstract
Simplified procedures (methods) are described to designlanalyze single and
multi-bolt composite joints. Numerical examples illustrate the use
of
these
methods. Factors affecting composite bolted joints are summarized. References
are cited where more detailed discussion are presented on specific aspects
of
composite bolted joints.
marized in the appendix.
Design variables associated with these joints are
sum-
