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  1. 1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 38 SAFETY FEATURES MODELING FOR INTEGRATION IN DESIGN PROCESS Wolfgang Nzié1 , Jean Bosco Samon2 , Bonaventure Djeumako3 1 Senior Lecturer, Department of Mechanical Engineering, National School of Agro-Industrial Sciences, The University of Ngaoundere, Cameroon 2 PhD Student, National School of Agro-Industrial Sciences, The University of Ngaoundere, Cameroon 3 Senior Lecturer, Head Department of Mechanical Engineering, National School of Agro-Industrial Sciences, The University of Ngaoundere, Cameroon ABSTRACT Although a process or plant can be modified to increase inherent safety at any time in its life cycle, the potential for major improvements is greatest at the earliest stages of process development. At these early stages, the process engineer has maximum degrees of freedom in the plant and process specification. The engineer is free to consider basic process alternatives such as fundamental technology and chemistry and the location of the plant. The modeling of inherently safer process alternatives that we call safety features to be integrated in the process design is the main objective of this paper. This is because each CAPP domain (assembly, machining, inspection, safety, etc) has been treated independently. And the “feature-recognition” has been adopted as the unifying theme. Indeed integrate safety during the life period of machines is costly and sometimes destructive. For that purpose to be achieved safety features are defined and taxonomy attributed based on the function of the features. They are then classified into two main groups which are safety features incorporated in machine and those out of machine. These features are equally given nine criteria to characterise them. The study also presents an algorithm showing the safety integration optimization in earliest design stages. Keywords: Modeling, Features, Integration, Safety, Design Process. INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2014): 7.5377 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
  2. 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 39 1. INTRODUCTION Computer-Aided Process Planning (CAPP) has long been recognized to be an important component and enabler of Concurrent Engineering (CE). Proposed structures of generic CAPP support systems with CAD data (object Information) exist [1-3] Design is the synthesis, the putting together, of ideas to achieve a desired purpose [4]. The design process does not only consider the final purpose but equally looks at other important aspects amongst which is safety. Safety is defined as freedom from those conditions that can cause death, injury, occupational illness, damage to or loss of equipment or property, or damage to the environment [5] Hale et al. (2007) make it clear that design errors are the causes of 20 to 60 percent of the accidents on installations. These errors are more rampant in new design since only proactive information is available and there is still a gap between the designer’s view and the user’s view which equally needs to be considered in the design process [6]. Users in order to correct the errors or reduce the risk associated carry out modifications on the system which is costly and can be destructive. To solve this problem of cost and destruction, the modifications done can be integrated in the upcoming design in the form of features. This is based on the fact that design is the first stage in system’s development and so design offers the earliest, and hopefully the cheapest place to intervene and get it right. This time around, the design process is both proactive, projecting new designs into their future use situations, and reactive, feeding back experience gotten from using earlier designs. In other words, it needs to incorporate both explicit and implicit modalities [7]. It is in this light that this project treats the safety modelling features for CE purpose. The specific objectives set to help in attaining the objective above are: • Modelling of safety features (definition, identification, taxonomy (classification) and characterisation of safety features); • Integration of safety in process design (representation of the design feedback process and establishment of an algorithm which can be followed to integrate safety in design based on risks presented by already existing machines); To achieve these objectives, this work will begin with a literature review, which will be closely followed by a description of the materials and methods used. Then the results obtained will be presented and discussed and work will then be crowned with a conclusion. 2. LITERATURE REVIEW 2.1 The different aspects of safety Generally, safety in an industry refers to four aspects. The first aspect of safety is related to the installation which in most cases is made up of the machines in the production line. The production line takes in raw materials and sends out finished products. Thus the next aspect considered is the safety of the product. Equally the installations need man power (personnel) consisting of those who intervene directly or indirectly on the installations to ensure a proper running of the process. This is the most vital aspect since it deals with human life. Lastly, there is safety with regards to the environment which is also very important since human beings make up part of the environment.
  3. 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 40 2.2 Features and their classification Different authors define features in different ways. Dixon et al. (1987) say a feature should be comprehended as a professional terminology which has attribute of both form and function and the name and meaning of which can be associated with its special geometrical form, topological relation, typical function, drawing expression, manufacturing technology and tolerance demand [8]. Motavalli et al. (1997) emphasize that a feature is defined by the specific syntax and contains data such as mathematical representation; classification which can be either protrusion or depression; orientation with respect to other features or user defined coordinates system; and its geometric and topological structure [9]. The tolerance demand mentioned in the above definition is a geometry data which describes the manufacturing requirements of a particular feature. Some manufacturing related data such as tolerances can also be added to the feature geometry data to describe manufacturing requirements of a particular feature. Other definitions of feature include that of Nzie (2002) where a feature is a group of characteristics (information), relative to the geometry, technology, functions and other attributes of an object such that it can be used in the domains that intervene in the design process [10]. A feature can also be seen as a representation of shape aspects of a product that are mappable to a generic shape and functionally significant for some product life-cycle phase [11]. Feature classification varies from one author to another depending on his needs. Pratt classifies features according to their domain of application [12]. Wenfeng’s own classification is based on function and form since a feature’s function determines its form, processing and assembling demands [13]. Dinesh (1999) classifies form features under positive or negative form features [14]. These negative form features are equally known as machining features since they are obtained from machining processes. They are mainly holes, slots, pockets etc. Also, geometrically, features can be classified under regular shaped features and freeform features [15]. Features can equally be classified into five groups with respect to the role they play in the system. • Functional features which are those features relating to the principal function of the system in question. • Assembly features which can be defined as the features used in linking single components of a product together [16]. Lee and Andrews (1995) define them as elementary relations between components extended with some assembly information [17] while (De Fazio, 1990) sees them as a collection of elementary relations matching form features [7]. Lastly, an assembly feature can be seen simply as an association between two form features present on different parts [18]. • Maintenance features which refer to those dispositions considered in a system to ensure its maintainability [19]. • Safety features which should be dispositions that avoid or prevent damage to people, system and environment. • Manufacturing features which correspond to volumes in a product that could be machined with a single or sequence of operations. 2.3 Modeling Modeling is the representation of an object or non-objects in the form of a model for its explanation [19]. It can equally be seen as the act of bringing out a representation of an object on a smaller scale. Generally, the model can either be quantitative (mathematical) or qualitative. The latter can be a representation of the prototype of a part or product. It can equally be a way of representing an item for a better understanding. That is the modelling spoken of in this work. A great deal of research has focused on modeling industrial engineering problems, over the last fifty years, resulting in a wide variety of tools. These tools include linear programming, fuzzy
  4. 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 41 logic, artificial neural nets, Petri nets, Genetic Algorithm, features (manufacturing, assembling...), etc. 2.4 Design and Feature based design Design is a human activity where the physical artifact or a part of it, which is under design, is not currently existent, but is believed to be so in the future [20]. The fact that the ultimate thing is not currently physically existent and cannot be observed and manipulated makes it necessary to represent the thing conceptually. Drogoul et al. (2007) define design as the process by which detailed specifications sufficient for unambiguous production of an entity [21]. Ernst and Stanislav (2008) give a more explicit definition of design: a process of formulating a description for an anticipated process system and/or an object system that is intended to transform an existing situation into a future situation to satisfy needs [22]. It has been found out that the environment is usually missing or not integrated in process models at the design stage. This has led to research work on the integration of the environment in the process model in which case the environment is represented using objects [20]. In this process safety is enhanced since manufacture follows the model simulated with the environment. Nevertheless, only an ideal environment can be modeled and as different risks show up in the existing process daily, it is difficult to eliminate all the risks using this method. Figure 2.1 illustrates the evolution of the deviations from nominal with the life of the system. And Figure 2.2 shows better safety opportunities while designing [23] (Greenberg, 1991). 2.4 Integration of safety in design Integration is a natural phenomenon, which raises the isolated activities to a higher level with a new sense on the basis of which the functioning of the whole is more efficient and more intelligent. Fadier and De la Garza (2006) state that there exist two safety integration methods [24]: • The direct method, which operate through standards, and other formal documents, design tools and actions. This is equally known as the explicit modality. • The indirect method, which correspond to the implicit and individual modality and operate through individual characteristics of each actor (knowledge, experience). The last method incorporates the feedback from the user. Generally, safety is considered in the design of any system via the first safety integration method. Nevertheless, errors do exist in the design process and are only noticed at the exploitation stage. These errors and deviations occurred are the causes of 20 to 60 percent of the accidents on installations [25]. These life cycle shortcomings are first checked and some corrected during design review but a certain percentage still moves up to be identified or not by the user. It should be noticed that a system’s development begins with design and so design offers the earliest, and hopefully the cheapest place to intervene and get it right. However, so many factors influence or shape the integration of safety in the design process. This is because safety, to a certain extend is an intangible cost incurred in the design of a system. As much as safety imposes additional requirements on the design that may add to costs and may lead to decreased profit margins or even loss of market share to competitors with less safe but cheaper design, the suffering and waste which can result from design errors and missed safety opportunities can never be under looked. Safe design can thus be seen as a design that allows and conditions, as far as feasible, safe use across the whole life cycle of the product. That is from manufacture, construction, transportation and installation, through use, maintenance and modification, to decommissioning, demolition and disposal. Even though a standard design process exists, it does not guarantee an error free design. This is because there is a gap between the designer’s view and the user’s view which equally needs to be
  5. 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 42 considered in the design process. Thus the design process needs to be both proactive (projecting new designs into their future use situations) and reactive (feeding back experience of using earlier designs) [25]. Figure 2.1: Evolution of the deviations from nominal with the safety integration in system design Figure 2.2: Effects of timing of design changes 3. METHODOLOGY Concurrent Engineering (CE) has become the new norm in new product development across the company worldwide, for organizing and managing all aspects of product process design and development activity for their products. The approach enables the integrated development of products and processes with the goal of completing the entire cycle in shorter time at lower overall cost with fewer engineering changes. So very early in the product design process the approach requires a multidisciplinary high level teamwork. That is functional disciplines such as, design,
  6. 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 43 manufacturing, assembling, maintenance, safety, marketing, etc. are involved. Obviously the design object view and design language are specific and often contradictory for each discipline [19]. But at the end common global language and view are to be achieved thanks to designers’ trade-off. Disciplines features as means of communication must enable this purpose. Hence for safety features modeling and their management in design process the figure 3.1 is illustrative for the methodology. Figure 3.1: Methodology layout The methodology presented in fig. 3 consists of two main steps which are modelling of safety features and integration of safety in design. Safety features exist but without a general or global nomenclature and classification. Thus, this first step which is safety features modeling consists of defining, identifying the different safety features, classifying them based on given criteria and finally characterizing them. This part will be basically assembly and modification of what is in literature. The next step which is the integration of safety in design consists of two parts: • Representing the design process as a feedback process and analysing it. That is the process from design through manufacture and installation to utilization. • Establishing an algorithm for the integration of safety in design process. In other words establishing a design procedure which considers reactive knowledge. 4. RESULTS AND DISCUSSION 4.1 Safety features Modeling A safety feature is defined in this work as a group of characteristics or information relative to the function, geometry, technology and other attributes of an object which enables it to eliminate or reduce hazards, protect personnel, installations, products and/or environment from the hazard or reduce the effects of any accident.
  7. 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 44 The different safety features identified are: • Elimination safety features. • Reduction safety features. • Active protection safety features. • Passive protection safety features. • Safe Working procedures. • Safety signs. • Personal protective equipment (PPE). • Emergency equipment. To ease comprehension, the above identified features can be classified as seen on figure 4.1. Generally, safety features can either be found incorporated in the equipment (machine) or out of the equipment. Figure 4.1 Safety features Taxonomy Thus the two main classes of safety features are: Safety features incorporated in machine which refers to the features found in the main structure of the machine, incorporated with the components of the machine during installation or even attached to the body of the machine. The features in this class are: • Inherent safety features: These are features that are formed directly on the main body or are joined inseparably to the machine. Thus these features eliminate or reduce the hazard and keep the machine safe. These features are ranked higher in priority since they are intrinsic and thus less costly and more effective.
  8. 8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 45 • Add-on safety features: These are features which are only added to the main body of the machine. They are equally known as protection safety features. These are features designed to protect the workers, product, environment or machine from risk. Here, it is the occurrence of the hazardous situation that is eliminated or reduced. These protective safety features can either be passive (do not need any power source) e.g. guards, or active (need a power source) e.g. fuses and relays or safety signs (which can either be regulatory (prohibition and mandatory), warning (caution and danger) or information (emergency and general information)). Safety features out of the machine are those which are not directly linked to the operation of the machine; are found neither in nor on the machine body and are not mounted directly onto an incorporated component of the machine. The features in this class are: • Emergency equipment which are used in cases of emergency. They include emergency stop buttons and fire extinguishers. • Safe working procedures are safety signs in that they do not ensure safety on their own. They are step by step instructions on how to operate a machine for a particular purpose. They can be procedures for the normal operation of the machine or for other aspects like their installation and maintenance. • Personal protective equipment are safety features used by personnel for their individual or personal protection. • Safety signs out of machine have the same function as the safety signs on the machine. Characterization helps in giving a complete and technical description of the feature. The characterization parameters proposed here are: function, shape or geometry, dimensions, manufacturing technology, position, material, colour and the nature of the information. • Function is the first and important point when it comes to feature characterisation because it is from this other parameters emerge. It refers to what the feature is to do in order to enhance safety. Generally, for inherent safety features, the function is to eliminate or reduce the hazard. For add-on features to protect against the hazard. For the specific functions, it is left to what precisely the feature does. • Shape or geometry refers to the look or the outfit of the feature. The simplest arrangement that permits the feature to accomplish its function effectively and is easy to manufacture. This is in the case of form features that emerge to assembling features. • Dimension refers to the sizes of the different measurable quantity. For the safety function to be accomplished, a particular size of the feature is needed thus its dimensions characterise the feature. For safety signs the size of the paper or plate should be conspicuous in order to draw the attention of the personnel. Thus with respect to where and for whom the sign is for, the size is determined. • Manufacturing technology refers to the manufacturing sequence that is used to realise the feature. Different technologies lead to different outputs especially in cases of precision. Thus the technology used in the manufacture of a particular feature gives knowledge on aspects like dimensional precision, strength, the nature of the surface etc. • Position refers to where it is located on the structure. The description here is most at times relative to other features. Two features can have the same shape and dimensions but their position can change their function.
  9. 9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 46 • Material refers to the internal make-up of the feature. The choice is made with respect to other parameters regarding the material strength, availability, cost and equally what the feature is to be used for. • Colour is one of the aspects that characterises safety features. Different colours pass on different messages. In some cases like in pipes, just the colour of the pipe is a safety feature because it gives information on what is being transported in the pipe and thus the personnel knows the safety precautions to take when in that zone. Active protective features have peculiar colours to indicate their function. • Nature of information is used for the characterization of safety signs and safe working procedures. For safety features, generally the information can be exclusively signs or text or mixed. On the other hand, safe working procedures can be in text form or can have illustrative pictures or diagrams. 4.2 Safety Integration in design process The feed-back process design illustrated in Figure 4.2 shows risk assessment at each step in the process. But it seems to not be relevant because we don’t have no information about the reactive Knowledge. Figure 4.2: Representation of evolution of the feedback design process 4.3 Proposed algorithm for the integration of safety in design As seen above, a machine passes through the design stage, is manufactured and installed before it can be used. This process starts with a study of design specifications occurred from the needs or the existing non satisfactory equipment. This involves having a knowledge of the primary and secondary functions of the equipment and there after its operation. It does not only end at the normal operation but goes further to look at the installation and maintenance operations involved. The next step consists of identifying already existing safety features and the risks they are actually reducing. This in other words is bringing out the present state of the machine with respect to System life Design stage Manufacture stage Installation stage Utilisation stage Risk assessment Reactive knowledge Proactive knowledge System performance+ +
  10. 10. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 47 safety. Note should be taken in this step since a risk reduction measure can be a hazard which should be assessed in the next step. The third step is risk assessment and this is a crucial stage since it is what gives the information to be fed back into the design process. This is done, with the exemption of already reduced risks. The aim of this assessment is to know the level of risk to which the equipment, personnel and environment are exposed, this being the focal point. The risk assessment method adopted will differ depending on the system in question and the available information. It will also depend on the competence or how versed the user of the method is with the method. It should be noted that since the concept of ‘zero risk’ is not real, acceptable risk is used as a reference in the procedure except in cases where two or more acceptable risks which have the same source show up. The question asked at this step is whether each risk identified and assessed is acceptable or not. If it is acceptable, the design is maintained. On the other hand; if not, the designer goes to the next question which aims at knowing if the risk can be eliminated or removed. If it can, the elimination safety features modeling for that starts. On the contrary, if the hazard cannot be removed, a check to know if it can be reduced is done. If the answer to risk reduction is yes, the modeling of risk reduction features starts. If no, another check is carried out to know if there is a possibility of protection. In the case of a positive answer, protective features modeling starts in which case it can either be passive or active protective features with priority given to the passive safety features. Regulatory signs can equally be used here. In the case of a negative answer, warning signs, safe working procedures, personal protective equipment or training can are adopted. Hazard evaluation is depicted in figure 4.3 while the integration algorithm of safety in design proposed in this work is shown in figure 4.4. As far as safety is concern in the design process the modification leads the modeling of safety features to eliminate, to reduce or protect the design system to danger at each step of the process. Figure 4.3: Hazard evaluation
  11. 11. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 48 5. CONCLUSION Unsafe design Safe design Design Utilisation stage Installation stage Manufac- turing stage Start Study of equipment operation Identification of existing safety features Risk assesment Safety signs, safe working procedures, PPE and training. Equipment operational? Can hazard be removed? Acceptable risk? Can risk be reduced? Protection possibility? Inherent safety feature Protection feature D E S I G N P R O C E S S Maintain design Feature modeling Yes Yes Yes Yes Yes No No No No No Figure 4.4: Procedure for the integration of safety in design through the feedback process
  12. 12. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 49 In this work, we presented how safety features can be defined, identified, classified and characterised. To summarise, these features were classified based on their position and function. As concerns their characterisation, it was done based on nine criteria which are function, shape, dimensions, manufacturing technology, position, material, colour and the nature of the information. We equally presented the design feedback process, which shows how reactive knowledge from the user gets back to the designer for safety design amelioration. An algorithm was brought out to ease the work of the designers as concerns the safety of the equipment. In perspective for safety integration in design process to be relevant, mainly in CE (Concurrent engineering), a genuine safety language is to be designed for communication with other disciplines designers. 5. REFERENCES [1] Wong S. Y., “Automated Geometric feature Recognition – An essential Component for Automated Design for Assembly”, M Phil Thesis, City Polytechnic of Hong Kong, 1992. [2] Venuvinod P.K., Yuen C.F., “Efficient Automated Geometric Recognition Through Feature Coding”, Annals of CIRP Vol. 43/1/1994, pp 413-416. [3] Yuen C.F, Venuvinod P.K. “Geometric Feature Recognition: Coping with Complexity and Infinite Variety of Features” International Journal of Computer Integrated Manufacturing, Vol.12, N0 .5, 1999, pp 439-452. [4] Sinnott, R.K., 2005. “Coulson and Richardson’s Chemical Engineering, Volume 6”, Fourth Edition, Chemical Engineering Design. [5] MIL-STD-882D, 2000 “Department of defense standard practice for system safety”. [6] Hale, A., Kirwan, B., Kjellén, U., 2007, “Safe by design: where are we now?” Safety Science 45, pp 305–327. [7] De Fazio T.L., 1990, “A prototype of feature-based design for assembly”, ASME advances in Design Automation, Chicago, IL, USA. [8] Dixon, J.R., Cunningham, J.J., Simmons, M.K., 1987, “Research in designing with features” In H. Yoshikawa and D. Gossard, editors, Proceedings of IFIP TC5/WG5.2 Workshop on Intelligent CAD. [9] Motavalli, S., Cheraghi, S.H., Rafie, S., 1997, “Feature-Based Modeling; An Object Oriented Approach”. Computer and industrial engineering, Vol 33. No.1-2, pp. 349-352. [10] Nzie, W., 2002. « Modélisation des features pour l’intégration de la maintenance en conception », 74p, Mémoire de DEA soutenu le 13 mai 2002 à l’UTBM, France. [11] Shah, J.J., Mantyla, M., 1995, “Parametric and Feature-based CAD/CAM—Concepts, Techniques and Applications” John Wiley & Sons, New York. [12] Pratt, M.J., 1991. “Aspects of form feature modeling geometric modeling”, pp 227-249. [13] Shah, J.J., Tadepalli, R., 1992, “Feature based assembly modelling” In: Gabriele GA, editor. Proceedings of the 1992 ASME International Computers in Engineering Conference, vol. 1, San Francisco, California, USA. [14] Wenfeng, L., 1996, “Feature modelling from 2D drawing and product information description”, Computer and industrial engineering, Vol 31. No.3/4, pp. 681-684. [15] Dinesh, S., 1999, “Feature-based Techniques for Handling Geometric Models”, National Centre for Software Technology, Juhu, Mumbai. [16] Eelco van den Berg, Willem, F.B., Joris, S.M.V., 2002, “Freeform feature modelling: concepts and prospects” Computers in industry 49, pp 217-233. [17] Winfried van Holland, Bronsvoort, W.F., 2000. “Assembly features in modeling and planning”, Robotics and Computer Integrated Manufacturing 16, pp 277-294 [18] Lee, K., Andrews, G., 1985, “Inference of positions of components in an assembly: part 2”, Computer-Aided Design.
  13. 13. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online), Volume 5, Issue 4, April (2014), pp. 38-50 © IAEME 50 [19] Nzié W. “Integration de la maintenance en conception: Application à un équipement Agro- alimentaire”, these de Doctorat soutenue à l’UTBM, le 27 février 2006, France. [20] Pohjola, V.J., 2003, “Fundamentals of safety conscious process design.” Safety Science 41, pp 181–218. [21] Drogoul, F., Kinnersly, S., Roelen, A., Kirwan, B., 2007, “Safety in design – Can one industry learn from another?”, Safety Science 45, pp 129–153. [22] Ernst, E.W., Stanislav, H., 2008 “Design engineering. A manual for enhanced creativity” CRC press, Taylor and Francis group Boca Raton, London, New York. [23] Greenberg, H. R. and J. J. Cramer. 1991. “Risk Assessment and Risk Management for the Chemical Process Industry”. Van Nostrand Reinhold, New York. [24] Fadier, E., De La Garza C., Didelot A., 2003, “Safe design and human activity: construction of a theoretical framework from an analysis of a printing sector”, Safety Science 41, pp 759–789. [25] Fadier, E., De la Garza, C., 2006. “Safety design: Towards a new philosophy”, Safety Science 44, pp 55–73. [26] Sachin B. Bende and Nilesh P. Awate, “Design, Modeling and Analysis of Excavator Arm”, International Journal of Design and Manufacturing Technology (IJDMT), Volume 4, Issue 2, 2013, pp. 14 - 20, ISSN Print: 0976 – 6995, ISSN Online: 0976 – 7002.