Although not a total substitute for testing, virtual reality simulation can reduce the amount of time required by allowing some reliability aspects of the design to be verified without or with reduced maintainability demonstration and testing.
Digital Twin simulations have definite applications for designing reliable equipment. For example, based on Digital Twin design status updates, a virtual copy of the product can be "produced."
Maintainability engineers can then enter a virtual design space where maintenance can be "performed" on the product.
Accessibility of components, whether an item fits in an allocated space, and the approximate time required to perform specific maintenance actions all can be evaluated using Digital Twin Simulations.
Virtual copies of support equipment can be evaluated by "performing" maintenance activities with them. Digital Twin Simulation reliability updates could allow technicians to view virtual information panels "superimposed" using augmented reality techniques on the actual equipment.
In general, Digital Twin Simulations can be used by reliability engineers to assess degree can be reached in time, access, field of view, force structure posture and activity timing. In addition to designing for maintainability,
Digital Twin Simulations have many potential training applications. Maintenance and manufacturing procedures, especially procedures that are seldom performed or are difficult to teach using conventional approaches, can be taught using Digital Twin Simulatons.
Digital Twin Simulations could also be used to train individuals in performing difficult to anticipate procedures. For example, Infantry Troops can now "perform" operations without actually using any physical tools or a live operations.
As has been the case with previous new technologies, the possible uses of Digital Twin Simulations cannot be fully appreciated or anticipated. As virtual reality interest moves forward, the applications related to design for reliability will certainly increase in number and in fidelity
Equipment is out in the field, it’s out with the troops, they’re giving the feedback. The engineers developing the systems are there right with them, so they are using it and giving very good feedback.
They get it down, they give special operators a chance to work with the equipment. They touch it, they use it, and then we can quickly turn those things around.
Getting the input of users is extremely important, or you won’t have a reliable system that they’re going to use when it gets fielded.
It’s similar to a special operations model, which has been an inspiration in the effort to streamline acquisition of system reliability as whole.
Site Visit Executive job will be to focus on defining requirements as precisely and realistically as possible from the start and then to experiment to see what works before committing resources to reliability efforts
There are going to be trade-offs and all this and the reporting lines may change to make sure we get accurate optimisation of Digital Twin Simulations.
Everybody recognises we have reached a point of action for reconstituting readiness that we’ve got to just move forward with smart reliability models. it’s time to move from this industrial age system to a modernised system utilise Digital Twin Simulations.
1. The programme must use a digital model to develop depictions of the system to support all programme uses, including requirements assessments, architecture, design and cost trades; design evaluations; optimisations; system, subsystem, component, and subcomponent definition and integration; cost estimations; training aids and devices development; developmental and operational tests and sustainment.
2. Models and simulations must be used, to the greatest extent possible, in systems engineering and program/project risk management; cost and schedule planning; and providing critical capabilities to effectively address issues in areas including but not limited to interoperability, joint operations, and systems of systems across the entire acquisition life cycle.
3. The responsibility for planning and coordination programme use of models, simulations, tools, metrics, and the engineering job sites belongs to the programme administration; the performance of the actual tasks may be delegated to the programe systems engineer and other program staff as appropriate.
4. Programmes should identify and maintain model-centric technology, methodology/approach and usage preferably in a digital format e.g., digital system models, that integrate the authoritative technical metrics and artifacts generated by all stakeholders throughout the system life cycle. Unless impractical, the programme should develop the digital system models using standard model representations, methods, and underlying information structures.
5. The digital system models are a collaborative product of systems engineering and design engineering efforts. The program should construct the digital system modes by integrating metrics consumed and produced by the activities across and related to the programme.
6. The digital system models must include, but should not be limited to, the technical baseline, parametric descriptions, behaviour definitions, internal and external interfaces, form, structure, and cost. This information must be traced at a minimum from operational capabilities through requirements, design constructs, test, training, and sustainment. The programme should validate the digital system models baseline at appropriate technical milestones.
7. Systems engineers should use models to define, understand, evaluate, communicate, and indicate the project scope, and to maintain an authoritative source about the system. When captured digitally, the system model may be used to produce technical documentation and other artifacts to support programme decisions. It is expected that a properly managed, digitally based system model will be more accurate, consistent, and sharable.
8. Models, simulations, tools, methodology, and data employed in acquisition activities must have an established level of trust, and the programme must use the activities with an acknowledged level of risk appropriate to the application. The development of models, construction of simulations, and/or use of these assets to perform programme definition and development activities and Materiel Development Decision and requires collaboration among all project stakeholders and is led by the systems engineer.
9. The programme directorate must ensure sufficient training in the appropriate use of models, simulations, tools, data, and the engineering job site. The programme must identify metrics that show the link between training and the appropriate use of activities that result in benefits to the programme, especially in the areas of early identification of defects, cost avoidance, and risk reduction.
10. The programme should update the digital system models throughout the program life cycle and maintain configuration management i.e., version controls. These updates will provide continuity among all programme stakeholders, including the program model developers, simulation uses, and other engineering and programme administration activities.
Top 10 Evaluation Summary of Reliability Detection Models Predictions Included with Element Rationale
Reliability critical elements of the item extracted from the reliability modeling and reliability prediction effort must be listed and included in the summary to include conditions of high failure rate elements, over stressed parts i.e., exceed established parts rating criteria, and mission reliability single failure points. The detail tasks and methods for preparing reliability models and perfecting reliability predictions follow
The Basic Reliability model must consist of a reliability block diagram and an associated mathematical model. By definition, the Basic Reliability model is an all Series model which includes elements of the item intended solely ‘for redundancy and alternate modes of-operation.
The Mission Reliability model must consist of a reliability block diagram and an associated mathematical model. The Mission Reliability model must be constructed to depict the intended utilisation of elements to achieve mission success. Elements of the item intended for redundancy or alternate modes of operation ~must be modeled in a parallel configuration or similar construct appropriate to the mission phase and mission application.
1. Reliability Block Diagram
Reliability block .diagrams must be prepared to show interdependencies among all elements-- subsystems, equipments, etc.or functional groups of the item for each service use event. The purpose of the reliability block diagram is to show by individual shorthand the various series-parallel block combinations that result in item success. An understanding of mission definition, of item and service use profile is required to produce the reliability diagram.
2. Block Diagram Title
Each reliability block diagram must have a title including identification of the item, the mission identification or portion of the service use profile addressed, and a description of the mode of operation for which the prediction is to be performed.
3. Statement of Conditions
Each reliability block diagram must include a statement of conditions listing all constraints influencing the choice of block presentation, the reliability parameter or reliability variables utilised in the assessment, and the assumptions or simplifications utilised to develop the diagram.
4. Statement of Success
A statement of success must be defined in specific terms stating exactly what the calculated reliability represents for the items as diagramed and performing under the criteria presented in the statement of conditions.
5. Order of Diagram
The blocks in the diagram must follow a logical order which relates the sequence of events during the prescribed operation of the item.
6. Block Representation
The reliability block diagram must be drawn so each element or function employed in the item can be Identified. Each block of the reliability block diagram must represent one element of function contained in the item. All blocks of the reliability block diagram shall be configured in series, parallel, standby, or combinations thereof as appropriate.
7. Identification of Blocks.
Each block of the reliability block diagram shall be identified. Diagrams containing few blocks may have the full Identification written in the block. Diagrams containing many blocks shall use a consistent and logical code identification written for each block. The coding system shal1 be based upon the work breakdown structure work unit code numbering system or other similar uniform identification system that will permit clear traceability of the reliability block to its hardware or functional equivalent as defined in program documentation. The code must be identified in a separate listing.
8. Non-modeled Elements
Hardware or functional elements of the item which are not included in the reliability model must be identified in a separate listing utilising the coding system. Rationale for each element exclusion from the reliability model shall be provided.
9. Reliability Variable
Reliability variables shall be determined for each block and presented so association between the block and its variable is apparent. The reliability variable is a number-- time, cycles, events, etc. used to describe the duration of operation required by each block to perform its stated function. This variable must be used in calculating the reliability of the block.
10. Block Diagram Assumptions
Two types of assumptions shall be used in preparing reliability block diagrams:.technical and general. Technical assumptions may be different for each item and for each mode of operation. The technical assumptions shall be set forth under the statement of ‘conditions. The general assumptions are those applicable to all reliability block diagrams.
Top 10 Equipment Readiness Information for Product Support Item Decision Assign Reliable/Capability Models
While heavy military transport aircraft have very strict mission proﬁles, agile ﬁghter, trainer or attack type fleet usage variability aircraft are well known to experience substantial variability in their missions .
Once critical factors are identiﬁed in the aircraft design stage contributing to fatigue test performance, individual aircraft reliability tracking programmes are used to accumulate, so they cannot be tracked based on mission hours alone. So tracking program is necessary for agile combat type aircraft conducted with every the fatigue life status of each aircraft throughout its service life design, based on its own operational load spectrum
Amount of performance fatigue life consumed and the remaining life for each aircraft in the ﬂeet is assessed. One of the greatest beneﬁts of an individual aircraft tracking program is that calculated independently of other aircraft in the ﬂeet. Reliability Models based on individual design characteristics reveals loads monitoring can take place without a prior knowledge of the exact critical location.
Ideally, provided that wide spread in the rate of fatigue usage, sufﬁcient number of primary load carrying structures are routinely monitored, stresses at all critical locations hours on many aircraft. The fatigue accumulation rate is the individual aircraft fatigue damage values
Critical transfer function relating the monitored load are calculated using the standard location stresses. So change in the critical location an be accommodated through the design of transfer function to the new critical location. Some of the beneﬁts gained from the individual aircraft tracking program include:
1. Modeling of operations to stabilise the rate of fatigue life consumption,; life of an aircraft structure, knowledge of the actual load experienced by that structure is essential.
2. Drawing reliability comparison between design and usage spectra for each aircraft; with estimation of the fatigue life or damage status of major components on each aircraft based on loads monitoring in the primary structure of that aircraft and related to fatigue test results
3. Planning of maintenance action according to rate of fatigue damage accumulation for aircraft fleet reliability estimates, modiﬁcation of operations to stabilise the rate of fatigue life consumption, life of an aircraft structure, knowledge of the actual load experienced by that structure is essential.
4. Building an operational load reliability model in conjunction with ﬂight trials for application to a fatigue test and, where a safe-life may be stipulated, some aircraft are retired at a different number of ﬂight hours due to their to compare with early fatigue test metrics
5. Identifying the variability in response between aircraft calculated rate of fatigue damage accumulation being higher or lower than the reliability target rate because of operating ﬂeet under the same ﬂight conditions through assessment of mission severity, with prime factors driving individual aircraft tracking are the unique combination point-in-the-sky affects
6. Gaining better understanding of the loading scenario experienced by different aircraft in the ﬂeet and the availability of a good on-board reliability monitoring in conjunction with ﬂight trials metrics
7. Observing difﬁculties introduced by assumption that, if the ﬂeet average load factor exceeding curves matched that and structural redundancy at vertical tails of the design spectrum, the aircraft could be: operated until the design life, but operators of modern aircraft is likely to have a different systems
8. Designing future aircraft to be smart buyers in the acquisition of new aircraft for the same role; and usage spectrum to the design spectrum. The root bending moment of the component is the primary factor to assess.
9. Defining ﬂight trials metrics parameters to be measured on new aircraft or new monitor and ﬂeet-wide average load systems for the same aircraft to allow the more accurate calculation of critical components reliability
10. Seeking to maintain fleet structural integrity based on its reliability and identify operational overloads making individual aircraft tracking programme necessary. Test life extension must be substantiated by further fatigue tests to determine the next critical location and required repairs
Top 10 Mission Reliability Model Categories Standards Include Definition of Equipment Item Related to Reliability.
For Basic Reliability modeling; the item definition is simple - all equipments comprising the item are modeled in series. “All” equipments includes any equipments provided solely for redundancy or for alternate nodes of operation.
However, for Mission Reliability modeling, the item reliability model and mission success definition can become elusive problams especially for complex multimodal systems incorporating redundancies and alternate modes of operation.
In item definition, emphasis is placed on properly specifying reliability within the context of all other pressing requirements and restraints that comprise a functioning Item. A proper definition is important in order to establish meaningful requirements and goals
An adequate item definition aids in determining when the item is being used as intended, when it sees its anticipated environment, when its configuration has been changed beyond its original concept, as well as when it is performing its specified function.
Item reliability is defined as the probability of performing a specified function or mission under specified conditions for a specified time.
1. New item processed through a defense technical review activity for tasking and authorised for procurement that cannot be replaced with an existing item.
2. New item authorised for tasking that is contained in a new standard or revised superseding specification or standard that replaces prior items. This item will not be assigned stock number or an item standardisation code until a requirement for the item is generated.
3. Item authorised for tasking that has been included in standardisation an item reduction study but an intelligent decision could not be made due to lack of technical information.
4. New item processed through a defense technical review activity for tasking and authorised for standardisation but an intelligent decision could not be made due to lack of technical metrics.
5. Item no longer authorised for tasking which has been authorised for replaced by a new item as the result of new or revised standards superseding assigned specifications or standards
6. Item authorised for tasking which was initially identified for standardisation the result of a formal item reduction study and which was accepted as a replacement for one or more items not authorised.
7. Item authorised for tasking which as been included in an for standards item reduction study and which initially does not replace an item not authorised.
8. Item, which as a result of a formal item reduction study, is for procurement accepted as not authorised for tasking
9. Item authorised for tasking that has not yet been for procurement subject to item standardisation.
10. Item authorised for tasking that is in a specific procurement supply classification class or item name grouping consisting primarily of items which are one of a kind and, therefore, little or no potential exists for elimination of items through formal item reduction studies.
Top 10 Condition State Models Calculate Materiel Reliability Function When Service Life Estimates Not Directly Observable
At each observation moment to build reliability model, an indicator of the underlying unobservable condition state assessed, and the monitoring information is collected. The observation process is due to a condition monitoring system where the obtained information is not perfect so observation process doesn't directly reveal the exact condition state.
To match value of indications to the unobservable degradation state, a relationship between them is given by an observation reliability model. Time-dependent proportional condition state is considered to model equipment failure rate. Reliability Model Limitations include the problem of imperfect observations, and the problem of taking into account the condition state history of observations.
1. New, repaired or reconditioned materiel serviceable issue to all customers without limitation or restriction.
2. Serviceably and issued for its intended purpose but restricted to issue for training use only
3. Serviceable materiel requires or designated for test, alteration, modification, conversion or disassembly not to include items require inspection or tested immediately prior to use
4. Materiel involves only limited expense or effort to restore to serviceable condition accomplished in storage activity where materiel is located
5. Economically repairable materiel requires rework, repair, overhaul or reconditioning
6. Materiel requiring additional parts or components to complete end item prior to issue
7. Materiel determined to be unserviceable and uneconomical to repair
8. Materiel in stock suspended from issue pending condition classification where true condition is not known
9. Materiel returned from customers/users and awaiting condition classification
10. Materiel identified on item condition control record but turned over to service site