Particle fracture and debonding during orthogonal machining of metal matrix composites

This paper investigates the particle fracture and debonding during machining of metal matrix composite (MMC) due to developed stress and strain, and interaction with moving tool by finite element analysis. The machining zone was divided into three regions: primary, secondary and tertiary deformation zones. The tendency of particles to fracture in each deformation zone was investigated. The findings of this study were also discussed with respect to the experimental results available in the literature. It was found that particles at the cutting path in the tertiary deformation zone fractured as it interacted with tool. In the secondary deformation zone, particles interacted with other particles as well as cutting tool. This caused debonding and fracture of huge number of particles as those were moving up along the rake face with the chips. No particle fracture was noted at the primary deformation zone. The results obtained from finite element analysis were very similar to those obtained from experimental studies

Sudan and the Unbearable Lightness of Islamism: From Revolution to Rentier Authoritarianism

The regime ruling Sudan since 1989 represents a pioneering experiment in the field of Islamist politics, being the first case in which a movement affiliated with the Muslim Brotherhood managed to conquer power and hold on to it for a considerable time. During the late 1990s, internal and external pressures threatened the survival of the regime, leading the ruling class to abandon its ambition to represent a model of revolutionary Islamic governance. Oil exports provided a catalyst for this pragmatic shift, intensifying patronage-based relations at the expense of ideological affiliation. Seen from a political economy perspective, the Sudanese experience proves the flexibility of Islamism as an ideology, but also its failure as a political practice to constitute a real alternative to the authoritarian dynamics that are widespread in the MENA region