Using ABAQUS in a Manufacturing Environment at Honeywell

20 Pages·2004·1.74 MB·English

Using ABAQUS in a Manufacturing Environment at
*
Honeywell Federal Manufacturing & Technologies :
The Quest for Quality Parts Under Small Lot
Production Scenarios
James F. Mahoney, Jr.
Honeywell FM&T
Abstract: The diversity and complexity of current product designs require skillful manufacturers
to produce the needed small volume of parts effectively. Traditional methods have been to do trial-
and-error to produce good quality parts. Costs and flow times associated with prototyping are
skyrocketing. Survivability for manufacturers is at stake. Computer simulations are key to solving
production development issues facing industry today. The aid of high-performance computing
simulations has greatly enhanced the manufacturing expertise and knowledge at Honeywell
Federal Manufacturing & Technologies. The simulations augment the prototyping and
development stage and aid in solving production problems.
Keywords: Manufacturing, encapsulation, welding, forming, failure mechanics.
1. Introduction
Honeywell FM&T is a supplier of high-tech manufactured goods to the Department of Energy’s
National Nuclear Security Administration defense systems. Honeywell is responsible for a wide
variety of components and systems ranging from machined cases, forged metal parts, encapsulated
high-voltage electronics, guidance and radar electronic systems, and individual plastic and
mechanical parts. The volume of manufacturing is very low, on the order of 10–1,000 pieces per
build cycle. To maintain the high quality of parts within the diversity of manufacturing,
prototyping is necessary. With the low volume of required parts, the challenge faced is to fully
understand new and existing manufacturing processes to produce newly designed components and
systems.

* Operated for the United States Department of Energy under Contract No. DE-ACO4-01AL66850.

All data prepared, analyzed, and presented has been developed in a specific context of work and was prepared for internal
evaluation and use pursuant to that work authorized under the referenced contract. Reference herein to any specific
commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily
constitute or imply its endorsement, recommendation, or favoring by the United States Government, any agency thereof, or
Honeywell Federal Manufacturing & Technologies.

Copyright © Honeywell Federal Manufacturing & Technologies, 2004
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Traditionally, a manufacturing process was evaluated for specific applications by both machine
craftsmen and process engineers. The final output quality was formulated, in part, by the know
how (or “art”) of the understanding of the specific processes. To be maintained as a leader in
defense-related parts requires a high level of confidence in process operations. The combination of
an aging population of experienced personnel with new “computer literate” engineers integrated
with simulation solutions is the key to future success.
The objective of this paper is to illustrate the methodology and approach to integrating ABAQUS
Finite Element Method (FEM) solutions into a diverse manufacturing framework. This paper will
overview the challenges that Honeywell FM&T has faced over the past 20 years and suggest and
forecast directions for the simulation business for the next decade. Some specific examples will be
noted where traditional manufacturing is no longer able to cope with the complex receipt for
success and where simulations compliment traditional production methods.

2. Science-Based Manufacturing Approach
During the mid 1980s, manufacturing work was flourishing at the Kansas City Plant. The
development of both new defense systems and the maintenance of existing systems were at an all
time high. The product line of mechanical, electrical, and plastics required a diverse production
environment. Because of the small volume of each unique part, development costs amortized over
the systems were becoming excessive. The Kansas City Plant has the responsibility of producing
the wide diversity of parts at all levels of production quantities. The level of security on the parts
and systems also required a closed-door environment, even to many downstream component
suppliers.

The traditional role of ABAQUS [1] simulations was on the evaluation of manufacturing
processes that were difficult to understand. The art in manufacturing and the craftsmanship was
still required, even though many operations were changed to automatically controlled systems.
The population of experienced personnel was stable and aging.

As time progressed to the 1990s, the cost or value of the production work was given tighter
controls. The usage of Components Off The Shelf (COTS) was driving the electronics industry.
The requirements for new strategic defense systems had diminished. It was important to “get it
right the first time” on production builds. The formula for production success had to change. The
mid to late 1990s was a time of survival, a time to regroup and evaluate production, a time to keep
core processes, and a time to be reactive and agile to change. The focus of simulation, particularly
with the FEM-based tools such as ABAQUS, had to take a leading role. The birth of the Science-
Based Manufacturing (SBM) approach to production occurred in the late 1990s. The focus and
direction were paramount : in effect, shift emphasis on utilization of the simulation tools to the
front-end of process development, augment the work with the knowledge capture of the highly
experienced workforce, and yield high quality parts, using COTS, in a shorter amount of time. The
Department of Energy [2] suggested this approach to Honeywell FM&T via its broad definition:

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“Science-Based Manufacturing is our strategy to use scientific,
engineering, and computational tools to allow rapid realization
of defect free product to support the nuclear weapons stockpile.”

Specific to the Kansas City Plant was the focus on applying simulation tools to solve single and
multi-physics manufacturing problems. From the high level strategy, a more specific concept was
fostered for the SBM principles:

An infrastructure and tool set that will allow for a more
comprehensive approach to utilizing simulations before full
production commences and design/manufacturing decisions
are set.

This tool set included a vast array of software tools, with ABAQUS being in the forefront. The
approach to favor preproduction appeared impossible compared to the existing challenges in
current production operations. The strategy and approach needed additional resources. The
number of dedicated analysts expanded from 5 to 10, computer systems were upgraded from 4-
processor CRAY XMP machines to 128-processor high-performance computing platforms [3],
and appropriate ABAQUS licenses were procured.

The successful formula of today is an environment that models and simulates processes in
conjunction with the captured knowledge of experienced associates. In many process areas, such
as welding, metallurgists with 30 years of experience will work together with associates with only
2 years of production know-how. The acceptance and aggressive nature of the new workforce
toward computer applications has made the utilization of simulation tools, or the science-based
approach, a success.

Prototyping costs have become excessive over the last 10 years. The time it takes for these
evaluations has also escalated. The implementation of the SBM approach has been shown to save
thousands of dollars in front-end evaluations. The prototyping stage still exists, mostly virtual, and
in a capacity to produce hardware only on the most successful options or ideas. For example, to do
a prototype run of a welding operation requires machined parts to be designed and fabricated,
welding to be performed on a nonproduction schedule, parts to be sectioned, parts to be X-rayed
for porosity/cracks, and parts to be mechanically loaded for strength. A lot of 20 parts for each
geometry condition is not uncommon. Using the SBM approach, after initial validation and
verification have occurred, sequentially coupled thermal-structural simulations are performed,
varying both welding parameters and geometry. From this, only valid, acceptable production
conditions are brought forward for prototyping. Sometimes if known modeling risks are evident,
no prototyping is required. Safety reviews with large safety factors are of this type—known
quality indexes in the simulation models and solutions. The time using simulations has also been
shown to decrease the prototyping cycle from weeks to days.

The success in the implementation of science-based solutions was not easy. One of the early stages
was to evaluate all of the manufacturing processes. This is described as follows. Step 1: rate the
processes according to the importance in the core competency of the business, the “keepers” that
set the Kansas City Plant apart from other vendors. Step 2: determine if simulation tools such as
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ABAQUS are or can be applicable to solve the specific process problems. Step 3: list which
processes get the most attention, which ones are “low hanging fruit,” and which ones are too
complex and require craftsmanship to complete. (This last step is considered to be one of the
hardest steps because there can be a mismatch between what is best for business and what the
FEM analyst would like to understand, explore, and solve.)

Today at the Kansas City Plant the simulation solutions to manufacturing problems are
categorized into two areas. The first, getting most of the attention, are the computer simulations
focused on integrating the three-dimensional Computer Aided Design (CAD) information into
software programs that articulate motion, or scenes. Such simulations are performed with an
engineer’s eyes and with attention to interferences, states, or locations of parts, and with visual
scenes, and camera settings. It should be noted that these types of simulations sometimes use the
same baseline CAD information as the second category. This second area deals with FEM-type
solutions, focused on applying the proper physics to the process via verified software tools. Below
are descriptive examples of the two areas of simulation work:

Design-Type Computer Simulations
• Tool/Part Interaction
Interference, kinematics events
• Work cell placement
Machine movement, collision detection
• Assembly Modeling
Tool/hand placement, work instructions

Physics-Type Computer Simulations
• Structural
Fit and function, forming, assembly
• Vibration and Forced Response
All potted assembly, cleaning operation,
equipment calibration
• Thermal Stress
Environmental operations, solder stresses,
welding/brazing operations
• Molding operation
Injection molding/cooling operations
• Heat Transfer
Soldering/brazing/welding, oven cycles
• Custom Processing
Heat treatment, plating, drying

The implementation of ABAQUS as a general purpose FEM tool has gained wide acceptance for
many manufacturing applications. Sometimes it appears to be unlimited in its ability to solve the
physics-based problems encountered. The next section shall exploit some specific examples of the
utilization of the FEM for manufacturing problems.

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3. Examples at the Kansas City Plant
The diversity of the product line and manufacturing operations makes the Kansas City Plant rich
in opportunities for applying simulations during process development. Because of the small lot
production needs and the need for high quality parts, every effort is made to develop the processes
optimally the first time. ABAQUS/Standard and ABAQUS/Explicit have been used since the mid
to late 1980s, with a transition toward process development before production over the last 5
years.
In the later 1980s much of the focus was on using the software tools properly, integrating the tools
into a seamless environment, and building confidence in their applicability. Interest focused on
comparative values—the new process was a certain percentage better, but there was no was
validated confidence in the actual values. As time progressed, the development of new and
updated procedures within the software tools, the update in mesh sizes and qualities, and the
experience in analysts gave more credence to the actual resultant values. This direction is required
today when using the tools on process evaluations where the final output will be the suggested
solution to the manufacturing process. A lot of confidence is required. ABAQUS is one of the
cornerstones of this effort.
Following are some site examples in specific process areas. Sometimes it is unclear whether the
simulation is for design intent or manufacturing requirements. Remember that the design for
manufacturability suggests integration of ideas between the two areas and a design is only robust
if can effectively be produced.

3.1 Welding operations
Simulations to support weld operations fall into three categories, the first being the concern about
heat and the concern about getting surrounding parts too hot. This is shown in Figure 1, where the
temperature profiles (contours) are noted for a CO laser weld around a can assembly. The model
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is a pie section model. This simulation process is valuable for the review of temperatures far
removed from the weld profile. Within the weld pool where vapor recoiling is occurring,
temperatures are estimated based on varying thermal capacitances. The latent effects of
vaporization are estimated by convection losses to the environment. Another example is shown in
Figure 2, where the contours indicate areas where the laser radiation is impinging on the surface.
Based on the cavity radiation and absorptivities of the materials at the laser’s wavelength, the
process runs the risk of thermal cracking glass-to-metal seals. The same CAD model definition
can be used for a variety of process areas. This leads to the second category, the coupling of the
thermal model to the structural model. This is best described in upset forge welding.
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Figure 1. Typical thermal profiles during welding process.

Figure 2. Cavity radiation of low frequency energy onto a glass seal.
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In the forge welding simulation process, ABAQUS/Standard and ABAQUS/Explicit are
sequentially coupled through time. An axisymmetric mesh is used in a coupled electrical-thermal
procedure to produce temperatures that are read into the structural application for material
softening and deformations under axial loading. The ABAQUS/Explicit mesh uses quadrilateral
elements, while ABAQUS/Standard uses triangles generated from the same node map. (This
technique was used to prevent ABAQUS/Standard from terminating with errors on bad elements
during time recovery.) Figure 3 indicates the temperature profile over a softened deformed shape.
User subroutines are used to evaluate the “time at temperature” for diffusion to occur and create a
valid weld.

Figure 3. Welding of tubes into blocks: thermal
profiles during upset forging process.
Another coupled physics example is the inertial welding process. Just as in the forging process,
heat is introduced into the model, material is softened, and the model is formed together. But
unlike the coupled electrical-thermal-structural response of the forging process, the inertia process
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uses the friction user subroutine to develop frictional dissipations for heating. As
ABAQUS/Standard solves the increment, the energy loss due to friction causes the angular
velocity to slow down, thus reducing the heating on the next increment. Figures 4 and 5 show
typical outputs for the inertia welding process where two axisymmetric parts have been formed.
The later is the final deformed shape.

Figure 4. Typical run sequence for forging process.

Figure 5. Final shape section profile for inertia welding of two cylinders.
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In both the prior examples, caution has been given to the evaluation of friction and coupling
energy across individual parts. Actual sections of baseline parts correlated to computer runs have
allowed for the determination of these parameters.
The last category is one in which the strength of the weld is in question. This is based on the depth
of penetration, the materials in question, and the overall load path to failure. Figure illustrates
where a weld section has indicated porosity on the weld pool area. Computer models have been
constructed parameterizing the voids. Figure 6 illustrates a 4o slice of a cylindrical part with a
lower cylindrical void subjected to axial loads. The simulations use power law hardening models
for the various materials and shear failure damage to direct the shear path and suggest failure
loads. Heat-effected zones are estimated based on metallurgical section input.

Figure 6. Equivalent plastic strain (damage) to weld joints with porosities.

3.2 Mechanical actuator operations
This area of simulation has been the most challenging, and the approach varies between each
application. Most of this work done in the industry is focused on applying rigid body dynamics to
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the structures. The Kansas City Plant is mostly interested in the effects of tolerance and
manufacturing features on the operation of assemblies. This suggests that elastic collisions and
dynamic forces are important. Most of the assemblies today are formulated from both rigid bodies
and deformable bodies. Figure 7 shows a typical mesh of a working mechanism that operates
within 1–5 milliseconds.

Figure 7. Sample mechanism mesh using rigid/deformable bodies.

This method of solution has gained popularity for a number of reasons. The advantages to this
method follow:
• Derived elastic collision (restitution) parameters.
• FEM models built directly off CAD systems.
• Parts can be switched between elastic and rigid easily.
• Visual presence is very marketable.
• Mass/Center of Gravities extracted directly from parts.
• Allows for elastic deformations to be captured.

The main disadvantage of this method is the computational time. It is not uncommon to get time
constants on the order of a nanosecond to capture wave speeds through such a small mesh on a
steel part. A sample output might be the deformation and stresses in the center pin or the tolerance
shift in the bearings, as shown in Figure 8. Note that this response can only be found in either this
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