Life Cycle Model

The Life cycle model is one of two methodical concepts that build the basis for system engineering. Next to the Problem-Solving concept, which deals with the challenge of developing solutions for project management challenges, the Life Cycle Model aims to structure the life of an engineering system. The model divides the life cycle in four phases, which include development, realisation, utilisation and disposal. Each phase is defined by a distinct set of criteria, purpose and expected results. This allows for evaluation of technical systems according to their current life cycle phase.

Historic Background

The Life Cycle Model can not be clearly attributed to a single author (ref Bonnal). A range of similar models have been presented by the guide Project Management Book of Knowledge (PMI Standards Committee 1996) and the Project Management Handbook (Cleland & King, 1988). This articel is based on the work of Rainer Züst and Peter Troxler , who propose the use of the Life Cycle Model in a Systems Engineering context.

The Life Cycle Phases

Development Phase

Influence vs knowledge of engineering system

This early phase in the life cycle is crucial for the development of any Engineering System. Decisions are taken which will influence the whole life cycle while at the same time the influence on the system itself is decreasing the further the system develops. (ref 5) The development phase consists of four steps:

• Proposal for systems design

The proposal for systems design originates at the recognition of a need for change. The change may require an improvement of an Engineering System or its new development. Based on an assessment of the need, the decision wether or not to solve the challenge is taken.

• Preliminary study

The preliminary study aims to provide a broad picture of the challenge. It might include elements like stakeholder investigation and system demarcation. The target of the preliminary study is a clear problem description and a set of objectives which shall be addressed by a potential solution. Concept proposals are developed which are concretised during the main study.

• Main study

The aim of the main study is to specify the concepts in detail. The focus shifts from a broad perspective to the engineering system. The concepts are evaluated against the objectives in order to establish their suitability towards the problem solution and investigates wether issues like stakeholder involvement or critical components within the system are known and dealt with sufficiently.

• Detailed study

Within this phase detailed studies of the subsystems and their interrelation, which lead to detailed information about each sub solution and gives advice towards the implementation of the Engineering System.

Case Example Development Phase

The case company A, experiences unpleasant feedback from their customers on one of their products. The need for change is recognised and the decision to improve the situation is taken (proposal to system design). The company asses the extend of the problem. Internal as well as external factors are included in order to pinpoint the origin of the problems. The key stakeholders are identified and the area of solution defined. The search for solutions trough creative methods leads to the development of concepts, which may be evaluated by using tools such as Cost-Benefit Analysis or an evaluation matrix with a specific set of criteria (preliminary study). The preferred concept is specified and analysed in detail to establish the effect that can be expected to influence the system (main study). Finally each of the systems parts are studied in detail in order to ensure that the concept addresses all issues raised in the first step in a high quality.

Realisation Phase

The realisation phase covers the transition in between the development and utilisation phases. It can be divided in two major steps, which are system realisation and system installation. The system realisation includes task which transform the concept into a tangible system. Examples are the production of machinery or in case of IT and service systems the full documentation of the system. The system is ready to be implemented. The second phase describes the implementation itself. The system is rolled out, which includes the system's installation and the instruction of the customer/end-user.

Case Example Realisation Phase

Company A has developed a concrete concept to deal with its unsatisfied customer and chooses to update their existing product. The product updates are developed in accordance to the established objectives, defined in the previous phase. Documentation for the updated product needs to be released and customers, who are in possession of the previous product get informed about the possibility to upgrade and how they can implement it.

Utilisation Phase

The System is in operation and it's performance monitored by a suitable system. Deviations from the expected performance can be grouped into an unintended use of the system by the user or insufficient planning throughout development and realisation phase.

Case Example Utilisation Phase

Company A has implemented the update within the system. The monitoring is based on customer feedback. Depending on the significance of the feedback the company can decide whether a third iteration and redesign of the system is necessary. Smaller changes do not require a whole new Systems Engineering process.

Disposal Phase

The disposal phase describes the decommissioning of a system. The result of this phase is either a complete removal or a radical change of the original system. Ideally the disposal phase is considered during the development phase in order to allow a smooth removal of the system.

Case Example Disposal Phase

Company A continues to receives poor feedback on the updated product and decides to redesign the product one more time. The development of the third generation of the system is interrelated with the disposal of the previous one, as it acts as a successor.

Critical Review of the Life Cycle Model

generic model with little love to the detail. unclear application area, according chapter abstract system engineering but later a bit blurry with elements of design for environment and basic (technical) product development & design process.

Alternate Use of Life Cycle Model

Life Cycle Models are usually featuring similar phases as described above, but as their use-context and perspectives differ, the content of each phase might be subject to change. Following examples make use of the Life Cycle Model but are not related to Systems Engineering.

• Life Cycle Model in a sustainability context. It creates the basis for Life Cycle Sustainability Assessments and Life Cycle Management. Does include the stage of material extraction and is focussed on environment, business and social impacts of a product system (ref 3).
• Product Life Cycle. The life cycle from a business point of view. May include issues such as innovation diffusion, maturity of product/market (ref 2)

References

how do I make those work?

1. Züst, Rainer, and Peter Troxler. “No More Muddling Through: Mastering Complex Projects In Engineering and Management”. No More Muddling Through: Mastering Complex Projects in Engineering and Management (2006): 1-185. Web.
2. Klepper, S. (1996). Entry, exit, growth, and innovation over the product life cycle. AMERICAN ECONOMIC REVIEW, 86(3), 562-583.
3. UNEP-SETAC. Towards Life Cycle Sustainability Assessment. 2011
4. Bonnal, Pierre, Didier Gourc, and Germain Lacoste. “The Life Cycle of Technical Projects.”. Project Management Journal 33.1 (2002): 12. Print.
5. Haberfellner R. et al., 2002, Systems Engineering. Daenzer, W. et al. (Publisher). 11. Auflage, Verlag Industrielle Organisation, Zürich.