D. M. Kulkarni

The effect of specimen thickness on the experimental and finite element characterization of CTOD in extra deep drawn steel sheets

Recent experimental results by us have indicated that the load-drop technique can serve as a valid fracture criterion for predicting elastic-plastic fracture in extra deep drawn (EDD) steel sheets or in predominantly plane stress conditions. The purpose of this investigation is to examine the validity of aJ-integral as a fracture parameter and theJ-CTOD relation for the determination of critical CTOD in predominantly plane stress fracture (CTOD-crack tip opening displacement). Fracture tests were performed and experimental results were generated on fracture behaviour of EDD (0·06%C) steel sheets with CT specimens and using ‘load-drop’ as a fracture criterion. Critical CTOD was determined by using theJ-CTOD relation in addition to several existing techniques. A full 3-D finite element model was formulated to verify the critical load, critical CTOD and plastic-zone size. The critical CTOD was shown to increase with increasing specimen thickness and appeared to be approaching a higher limiting value. The characteristic features of predominantly plane stress fracture or general yielding fracture mechanics are summarized in conclusion

Role of IT in SCM environment

Information technology (IT) plays a major role in improving organisational competitiveness in the 21st century global market. Supply chain management (SCM) is the 21st century global operations strategy for organisational competitiveness. IT is considered the backbone for achieving integration across and beyond the enterprise. SCM and IT are two areas of research, which have attracted a lot of attention in academic and practitioners camps over the last decades. The discussion related to the deployment of IT and electronic commerce in SCM has fostered a discussion about IT enabled supply chains. This paper investigates the influence of different IT technologies in managing supply chain. A study observed that integration, standardisation, information sharing and visibility, customer service, and process improvement are the characteristics of IT enablers in SCM environment. While standardisation and integration of internal business processes enabled by IT provides the backbone for supply chain integration, lack of trust between supply chain partners, inadequate integration of internal business processes and information, lack of IT sophistication amongst the other supply chain partners are some of the factors that limit the potential of IT technologies.

Experimental and finite element analysis of fracture criterion in general yielding fracture mechanics

Efforts made over the last three decades to understand the fracture behaviour of structural materials in elastic and elasto-plastic fracture mechanics are numerous, whereas investigations related to fracture behaviour of materials in thin sheets or general yielding fracture regimes are limited in number. Engineering simulative tests are being used to characterize formability and drawability of sheet metals. However, these tests do not assure consistency in quality of sheet metal products. The prevention of failure in stressed structural components currently requires fracture mechanics based design parameters like critical load, critical crack-tip opening displacement or fracture toughness. The present attempt would aim to fulfill this gap and generate more information thereby increased understanding on fracture behaviour of sheet metals. In the present investigation, using a recently developed technique for determining fracture criteria in sheet metals, results are generated on critical CTOD and fracture toughness. Finite element analysis was performed to support the results on various fracture parameters. The differences are within 1 to 4%. At the end it is concluded that magnitude of critical CTOD and/or critical load can be used as a fracture criterion for thin sheets.

Effect of Cooling Medium on Fracture Toughness of Rotomoulded Product

In day-to-day life, usage of plastics is numerous. It offers variety of benefits compared to other materials in various sectors like house hold applications, agricultural industry, and packaging, etc. There are numerous methods for processing plastics. These include: blow moulding, injection moulding, rotational moulding, transfer moulding and thermoforming. Rotational moulding is a competitive alternative to other plastic manufacturing process, since it offers designers an opportunity to achieve an economic production of stress free products. Many products made by rotational moulding process using linear low density polyethylene (LLDPE) are widely used in outdoor applications such as boats, over head tanks, and car body parts etc. In such applications, fracture properties are considered to be critical from the quality characterization point of view. Selection of appropriate cooling medium plays vital role to enhance the quality of rotomolded products. In this paper, an attempt has been made to investigate the effect of cooling medium on fracture toughness of the rotationally moulded products. Fracture tests are carried out on a compact tension (CT) test specimens prepared as per the ASTM D 6068 (2012). The tests are performed on a universal testing machine. R-curve method is used to determine the fracture toughness (JIC) of rotomoulded products. From the experimental results it is found that rapid cooling method favours better fracture toughness of rotomoulded products. Therefore, it is recommended to use faster cooling aids like water cooling in rotational moulding process to achieve highest fracture toughness.