A Novel Rough-Fuzzy DEMATEL-TOPSIS Approach for Contractor Selection with a Sustainable Perspective

Introduction: The selection of sustainable contractors is a critical challenge faced by executive managers and procurement personnel in today’s competitive world. Each year, numerous industrial and manufacturing projects are delegated to contractors, and improper contractor selection can lead to project failures. The importance of this issue is especially evident in supply chain management, where choosing the right contractor based on quality, price, and timing is of great significance. Due to its unique position in telecommunications product manufacturing, the company under study has a large number of contractors, particularly in the mechanical sector. Recognizing the need for a clear framework and method for evaluating and selecting mechanical contractors within the Electro-Optic Industries Company (SaIran), this research aims to address this gap. It is noteworthy that given the sensitivity of projects and the significant outsourcing of modular product construction to contractors, the wrong choice of mechanical contractor can have serious ramifications regarding delivery time management, manufacturing costs, product quality, and the company's reputation.



Methods: This research develops a new framework for evaluating and selecting mechanical contractors, considering sustainability criteria. In the first phase, the internal power of each sustainability criterion is determined using the fuzzy AHP method, followed by identifying the internal relationships between these criteria using the fuzzy DEMATEL approach. In the second phase, the combination of internal power and the external impacts of the criteria results in the formation of a fuzzy power-relation matrix and the calculation of criteria weights. Finally, the fuzzy TOPSIS method is used to rank the contractors.



Results and discussion: The proposed model, which utilizes an integrated rough-fuzzy approach, can simultaneously assess internal strengths and the interrelationships among criteria while providing the necessary flexibility to manage internal and external uncertainties. This research demonstrates significant results by evaluating the effectiveness and performance of the model through a real case study of sustainable mechanical contractor evaluation and comparing it with other methods. The findings from the rough-fuzzy DEMATEL-TOPSIS method indicate that the five main criteria for selecting contractors include bid price, equipment, environmental management system, financial capability, and green and clean technology. Particularly in the current economic conditions and due to sanctions, the financial capability of contractors and the need for advanced equipment are of great importance. Given the economic conditions and sanctions, bid price should be considered the most crucial factor in contractor selection. The identified criteria reflect the positive impact of economic, environmental, and social sustainability on contractor selection, enabling managers to identify the best options and enhance their processes.



Conclusion: This research represents a significant advancement in sustainable contractor selection and introduces its innovative approach as an effective tool for managers. The provision of a fuzzy framework facilitates more accurate and effective decision-making in contractor selection and emphasizes the importance of focusing on sustainability in management processes. This model can serve as a comprehensive solution to address the challenges faced in contractor evaluation. Considering the combination of fuzzy sets and rough sets for the comprehensive management of internal and external uncertainties, the proposed rough-fuzzy method demonstrates a significantly different evaluation result compared to the other three methods. Therefore, the use of the rough-fuzzy method has a substantial impact on the final outcomes of the DEMATEL and TOPSIS methods.