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Management & Engineering Simulation System
Management & Engineering 01 (2010) 1838-5745
Contents lists available at SEI
Management & Engineering
journal homepage: www.seiofbluemountain.com
Research on Equipment Maintenance Spare Parts Allocation
Simulation System
Yanjun Liu*, Wei Wu, Chengming He
Department of Technical Support Engineering, Academy of Armored Forces Engineering, Beijing, China
KEYWORDS
Maintenance level,
Product structure,
Support processes,
Maintenance spare parts,
Allocation model
ABSTRACT
This paper posed the decomposition theory of equipment product structure based on the
Level of Repair Analysis (LORA), and analyzed the maintenance support processes of
different maintenance level. Then according to the technology of Failure Mode Effect and
Criticality Analysis (FMECA), this paper established the equipment maintenance spare
allocation model and simulation system. This paper provides decision-making rationale for
analyzing the maintenance support processes and determining the maintenance spare parts
and allocation concept.
© ST. PLUM-BLOSSOM PRESS PTY LTD
1 Introduction
Equipment is made up by a large number of parts through different connection ways. During the using stage, all of the parts may be
failure, and cause the equipment fault. So we should allocate a certain quantity of maintenance spare parts when deployed the
equipment. According to the technology of Reliability-Centered Maintenance Analysis (RCMA), the scheduled maintenance may be
classified as organizational, intermediate, and depot. When the equipment was used in a certain time or a certain mileage, according
to the functional status of equipment, we should implement scheduled maintenance at different maintenance levels to ensure that the
equipment is in good functional status. Spare parts required for scheduled maintenance were allocated according to scheduled
maintenance base by higher authorities based on maintenance plan. Therefore, determining spare parts required for planned
maintenance was based on maintenance support system, and with some certainty. When allocating the maintenance spare parts, we
should allocate a certain number of non- scheduled maintenance spare parts, besides the spare parts required for scheduled
maintenance, to ensure that fault equipment can timely access to the required maintenance spare parts and be repaired timely and
effective, when the equipment breakdown during the process of using. This paper focused on studying the problem of allocating the
non-scheduled maintenance spare parts, according to the decomposition theory of equipment product structure based on the Level of
Repair Analysis (LORA).
2 The Decomposition Theory of Equipment Product Structure Based on the
Level of Repair Analysis (Lora)
2.1 Related definitions
*
Corresponding author.
Email : [email protected]
English edition copyright © ST. PLUM-BLOSSOM PRESS PTY LTD
DOI:10.5503/J.ME.2010.01.007
40
Definition 1 The level , divided by the unit- level of responsible for maintenance tasks, which discriminated by the scope and depth
of equipment maintenance tasks and the place of maintenance, is called the maintenance level. Maintenance level may be classified
as organizational level, intermediate level, and depot level.
Definition 2 Based on the restrictions of maintenance level, according to the equipment product functional structure, the equipment
was decomposed until all the underlying decomposition unit parts can be repaired at the maintenance level, and constructed the
equipment product tree based on the maintenance level. This decomposition theory is called the decomposition theory of equipment
product structure based on Level of Repair Analysis (LORA).
The same equipment implemented the product structure decomposition at different maintenance levels. But the result is not the same.
The repair capacity of maintenance level is more powerful, the level of product structure decomposition is more low, and the
underlying decomposition unit parts is more many. For example, a component A, the limited maintenance level is intermediate level,
so when we decompose the equipment at the organizational level, we can not decompose the component A, and when the component
A is failure or damaged, the maintenance unit of organizational level can not repair it, and can only replace it, then convey it to the
maintenance unit of intermediate level. So the component A need to be stored by the maintenance unit of organizational level.
However, when we decompose the equipment at the intermediate level, we need to continue decomposing the component A until all
the underlying decomposition unit parts can be repaired at the depot level.
2.2 Basic steps of the decomposition theory of equipment product structure based on Level of Repair
Analysis (LORA)
The decomposition theory of equipment product structure based on Level of Repair Analysis (LORA) is based on the product
functional structure decomposition, and begins from the top to the bottom to decompose the equipment according to the maintenance
level. The decomposition can be carried on by the follow tow steps: first, we should execute the product functional structure
decomposition until the decomposed parts can not be decomposed. Second, we should determine the maintenance level of the
decomposed part in different levels from the top to the bottom, then we can gain the underlying decomposition unit parts.
Taking some type equipment A for example, the product functional structure decomposition was shown in Figure 1 (a). To
component C4, for example, when decomposed the equipment at the intermediate level, if the component C4 can not be repaired at
the intermediate level, we should take the component C4 for the underlying decomposition unit part, and component C4 need not be
decomposed. The equipment product structure decomposition tree diagram based on intermediate level is shown in Figure 1 (b).
A
B1
A
B2
……
C1
C2
C3
……
……
……
B3
B1
……
……
C4
D1
D2
……
E1
B2
B3
……
C1
C2
C3
……
……
……
C4
D3
……
E2
(a) equipment product functional structure
(b)equipment product structure decomposition
decomposition tree diagram
tree diagram based on intermediate level
Figure 1 Equipment product structure tree diagram
3 Equipment Maintenance Spare Parts Allocation Model
3.1 Process of equipment maintenance support
Clearing the process of equipment maintenance support is the basis for determining the equipment maintenance spare parts. When
equipment is failure or damaged, we should convey the equipment to the maintenance unit of organizational level. Through the fault
41
detection, localization, and isolation techniques to determine equipment failure units, base on the equipment product structure
decomposition at organizational level, we can determine the maintenance level of the failure units. If the maintenance unit of
organizational level has the ability to repair the failure units, we should take the well-repaired for the failure units by the maintenance
unit of organizational level, according to the maintenance manual to determine the repair technology and the required maintenance
support resource. Required spare parts for maintenance were supplied by the spare parts warehouse of organizational level. The
repaired equipment convey to the organizational unit. If the maintenance unit of organizational level can not repair the failure units,
we should convey the failure units or the equipment to the maintenance unit of intermediate level, and based on the equipment
product structure decomposition at intermediate level, determine the failure units whether can be repaired at this maintenance level. If
the failure units can be repaired by the maintenance unit of intermediate level, we should take the well-repaired for the failure units
by the maintenance unit of intermediate level, according to the maintenance manual to determine the repair technology and the
required maintenance support resource. Required spare parts for maintenance were supplied by the spare parts warehouse of
intermediate level. The repaired equipment convey to the organizational unit. If the maintenance unit of intermediate level can not
repair the failure units, we should convey the failure units or the equipment to the maintenance unit of depot level, and based on the
equipment product structure decomposition at depot level, according to the maintenance manual to determine the repair technology
and the required maintenance support resource. Required spare parts for maintenance were supplied by the spare parts warehouse of
depot level. The repaired equipment convey to the organizational unit. The process of equipment maintenance support at the
organizational level is shown in Figure 2.
organizational unit
output
fault equipment
convey
maintenance unit
of organizational
level
fault detection,
localization, and
isolation
determine
failure units
equipment product structure
decomposition based on
organizational level
determine
maintenance level
maintenance manual
(determine the repair
supply the
technology and the technology
required maintenance
support resource)
repair
convey to maintenance level
the failure units or the
equipment which can not be
repaired at organizational level
the spare parts
warehouse of
organizational level
supply themaintenance
spare parts
well-equipment
Figure 2 : The process of equipment maintenance support at the organizational level
3.2 Spare parts allocation model based on the process of equipment maintenance support
Based on clearing the process of equipment maintenance support, according to the technology of Failure Mode Effect and Criticality
Analysis (FMECA), we can built the spare parts allocation model based on the process of equipment maintenance support.
3.2.1 Determine the underlying decomposition unit parts set
According to the decomposition of equipment product structure based on Level of Repair Analysis (LORA), we can determine the
underlying decomposition unit parts set I at different maintenance level. I  I1 ; I 2 ;; I n , The I i in here stands for the
underlying decomposition unit parts. n is the total number of the underlying decomposition unit parts.
3.2.2 Determine the mapping set between the underlying decomposition unit parts and failure mode
Taking the underlying decomposition unit part I k for example, we can carry out the Failure Mode Effect and Criticality Analysis
(FMECA) to part I k , and determine the mapping set between the underlying decomposition unit parts and failure mode.


I k  I k  M k ,1  k ,1 ; I k  M k , 2  k , 2 ;; I k  M k ,m  k ,m 
42
Where
M k , j = the failure mode of the underlying decomposition unit part I k
 k , j = the failure rate of the failure mode M k , j
m = the total number of the failure mode of the underlying decomposition unit part I k
3.2.3 Determine the variety, number and configuration level of the maintenance spare parts
Based on the results of the FMECA, through the maintenance manual of the maintenance level, we can determine the repair
technology and the required maintenance support resource for each failure mode. Then we can get the variety of the maintenance
spare parts at this maintenance level.
The level of the maintenance spare parts configuration is as the same as the level of the decomposition theory of equipment product
structure based on.
Then we can determine the mapping set between the failure mode and the maintenance spare parts:
M k , j  ( Pk , j ,1 , t k , j ,1 ); ( Pk , j , 2 , t k , j , 2 );; ( Pk , j ,l , t k , j ,l )
Where
Pk , j ,l = the required maintenance spare part for repairing the failure mode M k , j
t k , j ,l = the number of the required maintenance spare part Pk , j ,l
n mmodel of Tthe required maintenance spare part Pl for the equipment in T0 period of time:
The number
0
Pl   t k , j ,l  Fi , j i , j , t dt
0
i 1that
j 1some unit put Q sets of equipment into service in T0 period of time, we can get the number model of the required
Suppose
n spare
m
maintenance
part P
T0l for the equipment in T0 period of time:
Pl  Q t k , j ,l  Fi , j i , j , t dt
i 1 j 1
0
Fi , j i , j , t  = the failure distribution function of the failure mode M k , j
Where
4 Equipment Maintenance Spare Parts Allocation Simulation System
4.1 System architecture
Equipment maintenance spare parts allocation simulation system is an interactive simulation system by the software way, which sets
up on the basis of computer hardware. The system is divided into six layers from top to bottom. The top layer is the Users of the
simulation system. User can operate on the three subsystems through the functional platforms and interfaces which provided by the
human-computer interaction (HCI) layer. The layer is not transparent to users from the fourth layer. Users need not care about the
language and hardware platforms which adopted by the simulation system. The hardware system which is in the bottom is the basis
to implement the simulation system. The hardware system provides a unified hardware interface and the same software platform for
implementing the software system. System language and system management platform is the method to implement the simulation
system. Through the interaction between upper and lower layers, it can achieve the purpose of the simulation system. The system
architecture of the software and hardware platform is shown in Figure 3.
human-computer
interaction
basic data maintenance
subsystem
simulation control
subsystem
simulation results
analysis subsystem
system management
platform
system language platform
operating system
system hardware
Figure 3 : The system architecture of the software and hardware platform
43
hardware implementation
Software implementation
the user of the
simulation system
4.2 System structure and module division
Equipment maintenance spare parts allocation simulation system is divided into: basic data maintenance subsystem of the system,
simulation control subsystem, and simulation results analysis subsystem. The core part is the simulation control subsystem, which
controls the activities of equipment maintenance support and to determine the maintenance spare parts allocation. The basic data
maintenance subsystem of the system is the basis for the simulation system, which contains: the result data of equipment product
structure decomposition based on Level of Repair Analysis (LORA), the result data of FMECA/the data of equipment maintenance
manual, and the data of simulation parameter. The basic data maintenance subsystem of the system provides the necessary data for
equipment maintenance support simulation. The simulation results analysis subsystem contains: process shows, results analysis, and
results output. It can offer the simulation results and suggestion to equipment maintenance spare parts allocation for user. The logic
between every subsystem is shown in Figure 4.
the user of the
simulation system
basic data maintenance
subsystem
simulation results
analysis subsystem
The result data of
equipment product
structure decomposition
based on LORA
process shows
results analysis
result data of FMECA
results output
data of equipment
maintenance manual
simulation control
subsystem
simulation schedule
control
maintenance support
process control
error detect control
Figure 4 The logic between every subsystem
4.3 Simulation process
The simulation process is shown in Figure 5. Simulation process contains: building the basic data maintenance subsystem of the
system, setting the simulation system parameter, maintenance support process and equipment maintenance spare parts allocation
simulation, and dealing with the simulation results. The basic data maintenance subsystem of the system and the simulation system
parameter is the basis for operating the simulation system. Maintenance support process and equipment maintenance spare parts
allocation simulation contains tow simulation module which operate at the same time domain in parallel. A simulation module is the
equipment failure simulation module, the other is the fault equipment maintenance simulation module. After initializing the
simulation system, the system operates this tow simulation module in parallel. Through setting the failure rate and failure distribution
function, fault equipment is generated in the time domain. Having the fault equipment, the system operates the fault equipment
maintenance simulation module under the rules. The fault equipment maintenance simulation module calls the basic data
maintenance subsystem of the system based on the maintenance support process, and simulates the equipment maintenance support.
Finally, the system generates well-equipment. Then the system will continue to call the equipment failure simulation module under
the simulation rules until the simulation ends. In the simulation process, the simulation module of dealing with the simulation results
records and analyzes the simulation results in real-time, and outputs the simulation results after simulation end.
44
5 Conclusion
This paper posed the decomposition theory of equipment product structure based on Level of Repair Analysis (LORA), and analyzed
the maintenance support processes of different maintenance level. Then according to the technology of Failure Mode Effect and
Criticality Analysis (FMECA), this paper established the equipment maintenance spare allocation model and simulation system. This
paper provides decision-making rationale for analyzing the maintenance support processes and determining the maintenance spare
and allocation concept.
manipulator
the result data of equipment
product structure decomposition
based on LORA
the result data of FMECA
/the data of equipment
maintenance manual
the data of
simulation
parameter
database of
simulation
system
begin
simulation domain
initializing
simulation
initializing system
simulation mode
simulation schedule
Maintenance support process and equipment
maintenance spare parts allocation simulation
equipment failure
fault equipment maintenance
simulation module
simulation module
output the simulation
results
end
Figure 5 The simulation process
References
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Template (OMT) Specification [S], 2000.
[3]. Kosturiak Jan R, Gregor Milan, Simulation in production system life cycle, Computers in industry, 1998, 159-172.
[4]. Okuda T, Takashige T, Watanabe I. Simulation System Evaluating the Train Headway on Heavy Traffic Lines, Quarterly
Report of Railway Transportation Reasearch Institute, 1993, 119-124.
[5]. Xu Zongchang. Supportability Engineering[M]. Beijing: Weapon Industry Press, 2002, 158-165( in Chinese)
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