Interactive computer graphics technology is combined with a general purpose mechanisms computer code to study the operational behavior of three guided bomb dispersal mechanism designs. These studies illustrate the use of computer graphics techniques to discover operational anomalies, to assess the effectiveness of design improvements, to reduce the time and cost of the modeling effort, and to provide the mechanism designer with a visual understanding of the physical operation of such systems

Richter, B. J.

Welch, B. H.

English

NASA Technical Reports Server

N79-21880
An Application of Interactive Computer
Graphics Technology to the Design
of Dispersal Mechanisms
by
B. J. Richter and B. H. Welch
Lockheed Missiles & Space Company, Inc.
Sunnyvale, California
ABSTRACT
Interactive computer graphics technology is combined with a general purpose
mechanisms computer code to study the operational behavior of three guided bomb
dispersal mechanism designs. These studies illustrate the use of computer graphics :_ :
techniques to discover operational anomalies, to assess the effectiveness of design
improvements, to reduce the time and cost of the modeling effort, and to provide the
mechanism designer with a visual understanding of the physical operation of such
systems.
INTRODUCTION
A general purpose mechanisms computer code has been developed that accurately
simulates complex interactive dynamic behavior between the various components,
which comprise mechanisms. Mechanism components that can readily be accommo-
dated with this new simulation technique are exemplified by rollers, nonlinear springs
and dampers, linkages, actuators, and arbitrary constraint guides. In addition,
mechanical components that collide, rebound, slide relative to one another, and which
are subjected to complex environmental loadings, can be modeled with this code.
Guided bomb systems for dispersing large numbers of submunitions belong to a class
of mechanisms for which the mutual interactions between components are geometri-
cally complex, numerous, and depend upon initial conditions and external environmental
57
Precedingpa eblank
https://ntrs.nasa.gov/search.jsp?R=19790013209 2020-03-20T18:55:56+00:00Z
loading. For these dispersal systems all of the possible interactions between the
various components cannot be determined a priori and consequently must be calculated
during the dynamic process. Adequate assessment of motions and reactions for this
class of mechanisms is greatly facilitated by an interactive, visual, incremental-in-
time solution technique. The problem is initiated on the computer using known condi-
tions. By viewing the subsequent transient response via computer graphics, a pre-
viously unforseen interaction between mechanism components is detected. At such
time the problem is stopped, the new interaction is incorporated into the model, and
the problem is restarted. This incremental process continues for the desired time of
interest.
The followi:lg sections discuss three guided bomb dispersal systems whose basic
operation is similar. At a predetermined time, the vehicle is pyrotechnically severed
into a nose section, a tail section, a payload section, and three cover panels. The
dispersion of these components may be forced (e. g., internal pressurization of the
vehicle simultaneous to the pyrotechnic cutting charge), or may be due solely to
aerodynamic forces.
FIRST DISPERSAL SYSTEM
As a first step in analyzing the dynamics of a guided bomb dispersal system, the
computer graphics technique can be used to visually locate specific areas of potential
collisions between components. This is accomplished by performing an initial analysis
in which no impacts are included in the model, thus allowing bodies to pass through
one another. For the system depicted in Figure 1, operating with a given set of flight
conditions, it is found that: (1) the aft surface of the nose section will impact/slide
over the forward part of the payload section, (2) the aft tip of the winged, upper cover
panel will impact/slide along the cylindrical surface of the tail section, and (3) one of
the side cover panels initially moves radially away from the payload section but then
returns to impact it. The areas that have been identified can then be modeled to
simulate the forces generated by such impacts and the analysis can be rerun as shown
in Figure 2. This approach results in a great savings of both man-time and computer
time by eliminating the need to model the entire structure to account for all possible
impacts.
58
Even though a side cover panel impacts the payload section in the example shown in
Figure 2, the deployment of the payload is not seriously impaired. Under other flight
conditions, however, the behavior of this system was found to be totally unacceptable.
Figure 3 illustrates a case in which the winged, upper cover panel is aerodynamically
'trapped' against the payload section prohibiting successful deployment of the payload.
To avoid this anomalous behavior, the only practical design fix was to restrict the
operation of this system to certain vehicle angles of attack.
SECOND DISPERSAL SYSTEM
The example shown in Figure 4 is intended to illustrate two important aspects of using
computer graphics techniques to study dispersal systems. The first thing to be noted
is that two views of the dispersal sequence are necessary to comprehend the relative
positions of the various components. In this particular case, the nose section happens
to pass through the developing pattern of payload bodies untouched. Under slightly
different flight conditions it can be expected that the nose section wiil impact several
of these payload bodies. The design modification which was proposed to prevent this
anomaly consisted of rigidly connecting the nose and tail sections of the vehicle via a
center post. A combined nose/tail section was found to pitch much slower than the
original separate nose section thus easily avoiding impacts with the payload bodies.
This design solution was suggested by viewing the sequential pictures shown in
Figure 4. Hence, the second thing to be noted is that the computer graphics technique
can serve as a visual aid inspiring solutions to operational anomalies.
THIRD DISPERSAL SYSTEM
An example of a more complex dispersal system is illustrated in Figure 5. A side
view of the entire system prior to deployment is shown in Figure 5a while in Figure 5b
the three cover panels and the payload bodies have been removed to point out that the
four tail fins are attached only to the tail cylinder and are cantilevered out over the
59
cover panels with a small radial clearance or gap. Each of the tail fins is assembled
to the tail cylinder by fitting a tab into a mating slot on the tail cylinder as illustrated
in Figure 5c. The tab is then secured in the slot by a single break bolt.
This system was originally intended to operate as follows:
• the nose section, tail section, and cover panels are pyrotechnically severed
• a simultaneous pressurization of the payload section drives the cover panels
and the payload bodies outward
• the cover panels impact the cantilevered portion of the tail fins, prying them
away from the tail cylinder and failing the break bolts (see Figures 5d and 5e)
• the four loose tail fins are then pushed out of the way by the cover panels
allowing the payload pattern to develop
When this system was analyzed with the computer graphics technique as shown in
Figure 6, it was found that the forces required to fail the break bolts retarded the
deployment of the cover panels to such an extent that many impacts occurred between
the payload bodies and the cover panels. To correct this malfunction, a relatively
simple design modification was proposed which consisted of substituting pyrotechnic
bolts for the break bolts which attach the tail fins to the tail cylinder. This allows
the tail fins to be severed and aerodynamically carried away from the parent vehicle
just prior to the dispersal event. The deployment of the cover panels and payload
bodies can then be conducted without anomalous impacts.
C ONC LUSIONS
The merging of mechanisms technology with computer graphics technology has provided
the designer of guided bomb dispersal systems with a valuable tool for use throughout
the entire design process. Specific examples have been discussed which illustrate the
use of computer graphics techniques to discover potential design anomalies, to aid in
making design improvements, to reduce the time and cost of the modeling effort, and to
provide the mechanism designer with a visual understanding of the physical operation
of such systems.
6O
.'L
Figure i. First Separation System
Modeled With No Impacts
61
Figure 2. First SeparationSystem
ModeledWith Impacts
62
Figure 3. AnomalousBehavior
of First SeparationSystem
63
.z .........
0 0
I .
m
m
m
l
• g
g •
4, •
• o
o •
J I
% I I
% 0 0
I e
Figure 4. Second Separation System
e
64
REACTION
POINT "_
/
(a)
I
(c)
(b)
TAIL FIN
TAIL CYLINDER
BOLT
• F B BREAK
_-OV_PANE_°_'_H_O, OT
iF
, SPRING (e)
(d)
Figure 5. Details of Third Separation System
-----d
65
99
tuols._ uoi]_t_do_ pJIqj_ oql .zoj
oouonbo S luott_oIdocI jo _OIA pu[ff pu_ _OIA opIs "9 o,zn_Id
o o


An application of interactive computer graphics technology to the design of dispersal mechanisms

https://ntrs.nasa.gov/search.jsp?R=19780011089 2020-03-20T12:53:42+00:00Z
N78-19()32
2_n Application of Interactive Computer
Graphics Technology to the Design
of Dispersal Mechanisms
by
B. J. Richter and B. H. Welch
Lockheed Missiles & Space Company, Inc.
Sunnyvale, California
ABSTRACT
Interactive computer graphics technology is combined with a general purpose
mechanisms computer code to study the operational behavior of three guided bomb
dispersal mechanism designs. These studies illustrate the use of computer graphics
techniques to discover operational anomalies, to asses._ the effectiveness of design
improvements, to reduce the time and cost of the modeling _ffort, and to provide the
mechanism designer with a visual understanding o_ the physical operation of such
system_.
INTRODUCTION
A general purpose mechanisms c-)mputer code has been developed that accurately
simulates complex interactive dynamic behavioc bet_veen the various components,
which comprise mechanisms. Mechanism components that can readily be accommo-
dated with this new simulation technique are exemplified by rollcvs, nonlinear springs
and dampers, linkages, actuators, and arbitrary constrair:t guides. In addition,
mechanical components that collide, rebound, slide relative to one another, and which
are subjected to complex environmental loadings, can be modeled with this code.
Guided bomb systems for dispersing large numbers of submunitions belong to a class
of mechanisms for which the mutual interactions between components are geometri-
cally complex, numerous, and depend upon initial conditions and external environmental
57 " -_T " ,, . .° "v.._ ¢ .w J
.j" _,
loading. For these dispersal systems all of the possible interactions between the
various components cannot be determined a priori and consequently must be camulated
during the dynamic process. Adequate assessment of motions and reactions for this
class of mechanisms is greatly facilitated by an interactive, visual, incremental-in-
time solution technique. The problem is initiated on the computer using known condi-
tions. By viewing the subsequent transient response via computer graphics, a pre-.
viously unforseen interaction between mechanism components is detected. At such
time t'm problem is stopped, the new interaction is incorporated into the model, and
tt.e: problem is restarted. Thi o, incremental process continues for the desired time of
interest.
The following sections discuss three guided bomb dispersal systems whose basic
operaticn is similar. At a predetermined time, the vehicle is pyrotechnically sevexed
i_lto a ngse section, a tail section, a payload section, arm three cover panels. The
i,i_persion of these components may pc forced (e. g- ; internal pressurization of the
vehicle simultaneous to the pyrotech.ic cutting charge), or may be due solely to
aerodynamic forces.
FIRST DISPERSAL SYETEM
As a first step in analyzing the dynamics of a guided bomb dispersal system, the
computer graphics technique can be used to visually locate specific areas of potential
collisions between components. This is accomplished by performing an initial analysis
in which no impacts are included in the model, thus allowing bodies to pass through
one another. For the system depicted in Figure 1, operating with a given set of flight
conditions, it is found that: (1) the aft surface of the nose section will impact/slide
over the forward part of the payload section, (2) the aft tip of the winged, upper cover
panel will impact/slide along th_ cylindrical surface of the tail section, and (3) one of
the side cover panels initially moves radially away from the payload section but then
returns to impact it. The areas that have been identified can then be modeled to
simulate the forces generated by such impacts and the analysis can be rerun as shown
in Figure 2. This approach results in a great savings of both man-time and computer
time by eliminating the need to mode! the entire structure to account for all possible
impacts.
58
Even though a side cover panel impacts the payload section in the example shown in
Figure 2, the deployment of the payload is not seriously impaired. Under other flight
conditions, however, the behavior of this system was found to be totally unacceptable.
Figure 3 illustrates a case in which the winged, upper cover panel is aerodynamically
'trapped' against the payload section prohibiting successful deployment of the payload.
To avoid this anomalous behavior, the only practical design fix was to restrict the
operatioi_ of tkis :_yst_m to certain vehicle angles of attack.
SECOND DISPERSAL SYSTEM
The example shown in Figure 4 is intended to illustrate two important aspects of using
computer graphics techrAques to study dispersal systems. The first thing to be noted
is that two views of the dispersal sequence are necessary to comprehend the relative
positions oi the various components. In this particular case, the nose :_ection happens
to pass through the developing pattern of payload bodies untouched. Under slightly
different flight conditions it can be expected that the nose section will impact several
of these payload bodies. The design modification which was proposed to prevent this
anomaly consisted of rigidly connecting the nose and tail sections of the vehicle via a
center post. A combined nose/tail section was found to pitch muc h slower than the
original separate nose section thus easily avoiding impacts with the payload bodies.
This desigr, solution was suggested by viewing the sequential pictures shown in
Figure 4. tlence, the second thing to be noted is that the computer graphics technique
can serve as a visual aid inspiring solutions to operational anomalies.
TIIIRD DISPERSAL SYSTEM
An example of a more complex dispersal system is illustrated in Fi_mare 5. A side
view of the er.tire system prior to deployment is shown in Figure 5a v, hile in Figure 5b
the three cover l)ar_els and the payload bodies trove been removed to point out that the
four tail fins are attached only to the tail cylinder and are cant!levered out over the
59
cover panels with a small rsdial clearance or gap. Each of the tail fins is assembled
to the tail cylinder by fitting a tab into a mating slot on the tail cylinder as illustrated
in Figure 5c. The tab is then secured in the slot by a single break bolt.
This system was originally intended to operate as follows:
• the nose section, tail section, and cover panels are pyrotechnically severed
• a simultaneous pressurization of the payload section drives the cover panels
and the pa_ 'c.ad bodies outward
• the cover panels impact the cantilevered portion of the tail f'_ns, prying them
away from the tail cyliz, der and failing t!',e break bolts (see Fig_tres 5d and 5e)
• the four loose tail fins are then pushed otlt of the way by the co_,er pan,qs
allowing the payload pattern to develop
When this system was analyzed with the computer graphics technique as shown in
Figure 6, it was found that the forces required to fail the break bolts retarded the
deployment of the cover panels to such an extent that many impacts occurred between
the payload bodies and the cover panels. To correct this malfunction, a relatively
simple design modification was proposed which consisted of substituting pyrotechnic
bolts [or the break bolts which attach the tail fins to the tail cylinder. This allows
the tail fins to be severed and aerodynamically carried away £rom the parent vehicle
just prior to the dispersal event. The deployment of the cover panels and payload
bodies can then be conducted without anomalous impacts.
CONC LUSIONS
The merging of mechanisms teclmology with computer graphics technology has provided
the designer of guided bomb dispersal systems with a valuable tool for use throughout
the entire design process. Specific examples have been discu.ss_d which illustrate the
use of computer graphics tecbnlques to discover potential design anomalies, to aid in
making design improvements, to reduce the time and cost of the .nodeling effort, and to
provide the mechanism designer with a visual understanding of the physical operation
of such systems.
6O
• Figure 1. First Separation System!
I' Modeled Witb No Impacts
61
||
Figure 2. First Separation System
Modeled With Impacts
62
Figure 3. Anomalous Behavior
of First Separstion System
63
0 0
m
m
+
: i""i:
.'_..
W
Figure 4. Second Separation 8yetem
| 0
| P
0 e
o o
I i
o •
t
1t4
vTAIL FIN
REACTION __ \ /
POINT "_ (c) _ BOLT
/ F B BREAK
/ FORCE APPLIED ii POINT
/f----'-"-'--"__ BY COVER PANEL 1
F
d
BREAK BOLTI " I"__'_' / i.
i[e_
Figure 5. Details of Third Separation System
65
O O
O O
Figure 6. Side View and End Vl_:w of Deployment Sequence
for the Third Separation Sys_om
66



An application of interactive computer graphics technology to the design of dispersal mechanisms

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server

NASA Technical Reports Server