The fabrication of multilayer fiber composites by explosive welding is characterized by intense plastic deformation of the matrix material as it fills the spaces between fibers and by high velocity of the collision between matrix layers due to acceleration in the channels between fibers. The plastic deformation of the matrix layers and fiber-matrix friction provide mechanical and thermal activation of the contact surfaces, which contributes to the formation of a bond. An important feature of the process is that the fiber-matrix adhesion strength can be varied over a wide range by varying the parameters of impulsive loading

Cabelka, D.

Kotov, V. A.

Mikhaylov, A. N.

English

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NASA TECHNICAL MEMORANDUM	 NASA TM-77844
SOME FEATURES OF THE FABRICATION CF MULTILAYER
FIBER COMPOSITES BY EXPLOSIVE WELDING
V. A. Kotov, A. N. Mikhaylov, D. Cabelka
(b1A3k-TM- 77644) 	 SCMIS FLAiUri.S C° TH2
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20745
Translation o- "Nexotoryye osobennosti protsessa izgotovleniya mnogo-
sloynykh VKM 3varkoy vzryvom," in 5t h International Symposium on Com-
posite Metall ic Materials, Smolenice, Czechoslovakia, November 8-11,
_1 983. Proceedings, Slovenska Akademia Vied, Bratislava, Czechos ova ia,
1983, pp. 79-84.
'I f l `k c
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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, D.C. 20546
	 APRIL 19H5
STANDARD TITLE PAGE
1.	 Repoli No. 2. Go.omw.nt Accotuon No. )	 Roclplont'a Cotalo^ No,
NASA TM-77844
L	 T111a onf S.,bwlo 3.	 Repoli oat*
SOME FEATURES OF THE FABRICATION OF April 1985
MULTILAYER FIBER COMPOSITES BY 6. Pw(orulno Otoonicotian Codo
EXPLOSIVE WELDING
1.	 Auchel(c) L Pwlonons oryonicolirn Report No.
V. A.	 Kotov, A.	 N. Mikhaylov,
D. %abelka 10. RoAunitNo.
•. P t ,fe—np Ogan.t000n Nano on1 Add.ou U.	 Contract or Gtant No.
Leo Kanner Associates NASW-4005
11
	
Type of Repoli cnd P.,iod Co.ar.A 	 1Redwood City, California 94063
Translation
12.	 kentot.n3 Agency , Nome and Addrocc
National Aeronautics and Space Adminis-
tration,	 Washington,	 D.C.	 20546 id,	 sp.n..tln, A,.nc, cce.
iS.	 S^;;I.r..ntct^ Notot
Translation of "Nekotoryye osobennosti protsessa izgotovleniy
mnogosloynykh VKM svarkoy vzryvom," in 5th International
Symposium on Composite Metallic Materials, Smolenice, Czecho-
slovakia,
	
November 8-11,	 1983.	 Proceedings,	 Slovenska Aka-
demia Vied,	 Bratislava,	 Czechoslovakia,	 1983,	 pp.	 79-84.
lb.	 a.t..;^.
The fabrication of multilayer fiber composites by
explosive welding is characterized by intense plastic deform-
ation of the matrix material as it fills the spaces between
fibers and by high velocity of the collision between matrix
layers due to acceleration in the channels between fibers.
The plastic deformation of the matrix layers and fiber-matrix
friction provide mechanical and thermal activation of the
contact surfaces, which contributes to the formation of a
bond.	 An important feature of the process is that the fiber-
matrix adhesion strength can be varied over a wide range by
varyin g the parameters of impulsive loading.
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SOME FEATURES OF THE FABRICATION OF MULTILAYER
FIBER COMPOSITES BY EXPLOSIVE WELDING
V. A. Kotov, A. N. Mikhaylov, D. Cabelka
Explosion welding has found increasing use in recent years as a /80*
method of bonding different materials in the production of metal
sandwich composite and fiber composite materials (MSC and FCM). The
process flow diagrams, conditions for performing explosion welding of
sandwich composites, and features of layer bonding during explosion
welding of MSC are detailed in many works (151, for example). The
specifics of the FCM manufacturing process with explosion welding,
however, have so far been studied to a lesser extent.
The specific structure of the FCM blank undergoing welding (the
presence of numerous fibers in the zone of matrix layer impact) and
certain requirements associated with the subsequent mechanical be-
havior of FCM when loads are applied (in particular, the requirement
that there be no extraordinary local matrix fusion, and virtually no
waves in the bonding zone) define many features of the process of
FCM explosion welding relative to explosion manufacture of MSC.
One characteristic determined by the presence of numerous rigid
reinforcing fibers in the matrix layer contact zone is intense plastic
deformation of the matrix material when it flows into the gaps between
the fibers, which consist of channels of shrinking cross-section [6],
and marked increase in the impact speed of the matrix layer surfaces
because of matrix acceleration as it moves in these gaps [7]. If the
impact front propagates along the reinforcing fibers, the latter of
these circumstances produces a corresponding increase in impact angle
of the matr_ic layers in }he gaps between the fibers [7]. Plastic
deformation of the matrix-layer surfaces when they flow between the
fibers (the greater it is, the smaller the spacing of the fibers) and 	 Im
friction in the fiber-matrix zones when fibers are introduced into the
*Numbers in the margin indicate pagination in the foreign text.
1
--	 ^L
imatrix ensure prior mechanical and thermal activation of the layers
being welded, thus facilitating the formation of their bond.
Furthermore, when the reinforcing fibers are packed densely 	 /81
enough, explosion welding of FCM becomes possible with a transition
to substantially supersonic conditions, including at a contact-point
speed V  i - (i.e., welding becomes possible under flat projection
conditions as well); in the latter case, and also when the impact
front propagates at right angles to the fibers, a weld is formed if
the surfaces of the matrix layers collide much below the mid-point
of the reinforcing fibers. The possibility of obtaining FCM under
any supersonic conditions, including with flat projection, is
perhaps the most interesting feature of FCM explosion welding. This
feature, first established in [7], is also noted by the authors of [8].
Another important feature of the process of manufacturing FCM
with explosion welding is the possibility of obtaining fiber composites
with different fiber-matrix-adhesion resistance to direct pull, am-f'
within a rather wide range of values (to as much as a m_ f values close
to the matrix strength a m) through varying the technological parameters
of impact loading 181, which is characteristic only of explosion
welding and one of its chief advantages over other familiar methods
of manufacturing FCM. The mechanism of a m_ f change in the case of 	 I'
steel-aluminum FCM is regulating the amount of local matrix fusion in
areas of matrix contact with fibers [8].
In practice, when manufacturing multi-layer FCM with explosion
welding it is expedient to employ an "unwel_ded" massive metal plate
(MMP), which is merely an energy carrier that creates a high-momentum
impact on the FCM blank being welded [S]. On the one hand, the use
of MMP helps a great deal to regulate the energy expended in each
single impact of the layers, and thereby helps control the amount of
local matrix fusion in the areas around the fibers, which usually
occurs in FCM welded by explosion [9]; on the other hard, it helps
produce a more even distribution of energy through the layers. This /82
is directly implied by analysis of the explosion-welding energy-
2
•	 : 1
balance component losses in plastic deformation
C;; = i/' Lr m1v1 • m 2 / (ml + m2 ) ) (here m1 is the unit mass of the MMP) ;
v 1 is its speed; m 2 is the unit mass of the matrix plate) [3] and the
law of conservation of momentum. In addition, the use of MMP helps
practically eliminate waves when welding a multi-layer stack l , which
follows from [11), in which an examination of wave-formation theory
makes a theoretical predication of and experimentally proves the rela-
tion between wavelength and the experiment's parameters, in the form
(Here Y is the MMP impact angle). This relation, as well as the
expression for AW, contains ratio m 2/(ml + m 2 ). Clearly, increasing
the MMP mass when welding a stack of FCM containing thin matrix layers
(m2 << m1 ) severely diminishes wave size, i.e., the use of MMP when
manufacturing multi-layer FCM with explosion welding can be considered
a specific feature of this process.
When limiting (eliminating) wave formation in the process of
explosion welding of multi-layer materials in general, and FCM in
particular, one other feature, established in [12, 131, should also
be borne in mind. These works pointed out that a certain time,
t  = 0.6-1 Usec, is needed for complete development and "setting"
of the pattern of waves generated during the impact. If the impact
conditiDns change substantially during the time interval (0, t w )
(for instance, the stack being welded strikes a new layer), the wave
sizes also change (the waves become larger) in accord with these
impact conditions (a new mass ratio). So the presence of a charac-
teristic setting time tw for the tiave pattern imposes certain restric-
tions on the minimum size of the gaps between the layers being welded.
The time before collision with the next layers, t 3 , should ')e no less /83
than the time of development and setting of the wave at the given
bond boundary, i.e., condition t  < t 3 must be met, from which it is
1 Discussion of possible wave formation during explosion welding of FCM
makes sense in the case of sparse enough packing of the reinforcement.
3
rev,
2 A indicated by evaluation of the time of fiber
matrix layers [7],when explosion welding FCM with
d > 0.3 min the condition t  < t 3 is met, as a rul
4
easy to determine the required size of the gap between layers.2
Considerat -ion of these features when manufacturing FCM with
explosion welding produces high-quality fiber composites. For example,
the use of explosion welding by one of this work's authors to manu-
facture steel-aluminum FCM made it possible to obtain a spectrum of
FCM with Qm_ f values from 0 to (0.7-0.8)am (the Tm-f varying between
0.5 and 1Tm ) with virtually no perceptible damage to the fibers or
matrix [9, 14].
REFERENCES
1. Deribas, A. A., Fizika uprochneniya i svarki vzryvom [The Physics
of Reinforcement and Explosion Welding], Novosibirsk, 1972.
2. Sedykh, V. S.(ed.), Svarka i svo stva svarn kh so edineni
[Welding and the Properties of Welds], Issues 1 and 2,
collections of articles, Volgograd, 1974 and 1975.
3. Sedykh, V. S., and A. P. Sonnov, "Calculation of the energy
ba ance of the explosion-welding process," FiKhOM, 2, (1970).
4. Cowen, G., J. Douglas, A. Holtzman, "Explosive Bonding," U.S.
Patent No. 31377.937, Ser. No. 65194. 12 claims, CJ 29-486.
5. Krupin, A. V. et al., Deformatsiya metallov vzryvom [Metal Deform-
ation by Explosion], Moscow, 1975.
6. Kotov, V. A., and V. N. Karpov, "Calculation of unsteady deform-
ation of a flexible plastic half-space with the introduction of
numerou ,_ rigid fibers into it," Tezisy dokladov Vsesoyuznoy kon-
ferentsii molodykh uchenykh po nekhanike deformiruyemogo tver-
dogo tela [Abstracts of Reports at the All-Union Conference of
Junior Scientists on the Mechanics of a Deformed Solid],
Kuybyshev, 1976.
7. Kotov, V. A., dissertation, Volgograd, 1974.
8. Kotov, V. A., and V. S. Sedykh, "The mechanism of bond formation
of steel fibers with a matrix of aiuminum alloys when obtaining
FCM by explosion welding," in collection Svarka vzryvom i svoy-
stva svarnykh soyedineniy [Explosion Welding and the Properties
of Welds], 2nd Issue, 1975.
9. Kotov, V. A., "Some structural features and the mechanical proper-
ties of fiber composite materials obtained using explosion
energy," Sbornik trudov 5-go mezhdunarodnogo simpoziuma po
ispol'zovaniyu energii vzryva dlya proizvodstva metallicheskikh
materialov s novymi svoystvami [Proceedings of the 5th Inter-
national Symposium on the Use of Explosion Energy to Make Metallic
Materials with New Properties],Gottwaldov, Czechoslovakia, 1982.
10. Kriventsov, A. N., and I. A. Solov'yev, "Basic features of explo-
sion welding of fiber composite materials," Sbornik trudov 5-go
mezhdunarodnogo simpoziuma po ispol'zovaniyu energii vzryva dlya
proizvodstva metallicheskikh materialov s novymi svoystvami
[Proceedings of the 5th International Symposium on the Use of
Explosion Energy to Make Metallic Materials with New Properties]
Gottwaldov, Czechoslovakia, 1982.
11. Utkin, A. V., A. N. Dremin, A. N. Mikhaylov, Yu. A. Gordopolov,
"Hydrodynamic instability as a cause of wave formation during
high-speed collisions of metals," All-Union Institute for
Scientific and Technical Information Department of Scientific
Resources, No. 557 -80 dep.
12. Mikhaylov, A. N., A. F. Belikova, A. N. Dremin, "On the time of
development of the wave-formation process during oblique
collision of metal plates," All -Union Institute for Scientific
and Technical Information Department of Scientific Resources,
No. 1808 -80 dep.
13. Dremin, A. N., and A. N. Mikhaylov, "Observation of the wave-
formation process during high-speed oblique collision nf
plates using light reflection," Sb.trudov 4-qo mezhdunarod-
nogo simpoziuma po ispol'zovaniyu energii vzryva dlya polu-
cheniya materialov s novymi svoystvami [Proceedings of the
4th International Symposium on the Use of Explosion Energy to
Obtain Materials with New Prcperties], Gottwaldov, Czechoslo-
vakia, 1979.
14. Kotov, V. A., "A study of the strength of explosion-welded FCM
and tubular items ,Wade of them during single-axis and two-
axis loading," Sb. trudov 5-90 mezhdunarodno o simpoziuma po
kompozitsionnym metallicheskim materialam Proceedings of the
5th International Symposium on Metallic Composite Materials],
Bratislava, Czechoslovakia, 1983
15. Kotov, V. A., and D. Cabelka, "Study of the mechanical properties
of explosion-welded FCM at low temperatures," Sb. trudov 5-go
mezhdunarodnogo simpoziuma Fo kompozitsionnym metallicheskim
materialam Proceedings of the 5th International Symposium on
Metallic Composite Materials], Bratislava, Czechoslovakia, 1983.
s :7,.V'
	
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Some features of the fabrication of multilayer fiber composites by explosive welding

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