Showing 3 results for Failure
Hamed Saeidi Googarchin, Ali Qasemian, Mohammad Rouhi Moghanlou,
Volume 10, Issue 4 (12-2020)
Abstract
The primary objective of a brake disc is to absorb frictional heat during braking and dissipated it immediately by convection and radiation. However, during hard and repetitive brakings, thermal coning on brake disc generates surface hot spots which are responsible for the undesired accumulation of compressive stresses on the surface of the brake disc. These stresses would lead to disc cracking and finally failure of it. In the current paper, a coupled transient thermo-mechanical FE analysis of a heavy vehicle braking system is carried out in a way that thermal coning of the disc and surface hot spots and bands are recognizable. Braking condition is chosen from a standard for hard braking in trucks. Moreover, five additional braking actions with different severities are investigated to study the effects of braking severity on thermo-mechanical instability of brake discs. Comparison of numerical results of transient temperature during braking and cooling phases with experiment reveal a high accuracy of thermal prediction of this model. Also, the results show that thermal coning of brake disc is varied between 0.05 to 0.7 mm depending on braking severity and tangential location of the disc. Additionally, surface hot spots experience higher temperature gradients in higher decelerations. Finally, results show that circumferential compressive stresses during braking are the major component of thermal stresses and should be taken into account for life estimation analysis.
Mr. Nasrollah Taghizadeh, Dr. Mohsen Esfahanian,
Volume 14, Issue 1 (3-2024)
Abstract
Due to the importance of vehicle weight reduction which can reduce fuel consumption and air pollution, changes are made in vehicles. In heavy trucks with payload limitations, a lighter trailer can provide higher load-carrying capacity and more economical benefits. Composite materials are a good candidate for material exchange due to their resistance to various conditions and low weight compared to steel. In this paper, the trailer material made of steel will be replaced by composite so that strength density will remain the same. For this purpose, the finite element method is used for static and dynamic analyses. At first, the model of a two-axle trailer is developed using SolidWorks software. Then, using standard loading and failure theories (Tsai-Hill, Tsai-Wu), the number of composite layers and their suitable angles are selected for the chassis. Finally, the loaded trailer's static, modal, and dynamic analysis are performed using the finite element method with a composite material. Results show that 17 layers of polymer composite with glass fibers with 0-0 angle can reduce 17.7 percent weight.
Dr Mohammad Shirzadifar, Dr Javad Marzbanrad,
Volume 14, Issue 1 (3-2024)
Abstract
The corrugated composite plates have wide application to improve the energy absorption and failure behavior of panel structures. The roof panel of the bus could benefit from the use of these structures to reduce impact failures in rollover accidents. The aim of this paper is to design a new configuration of bus roof panels stiffened with multi-layer semi-circular corrugated CFRP plates to minimize structure failure during rollover accidents. An analytical failure equation of Tsai-Hill index for the new proposed panel subjected to dynamic impact loading has been derived. The failure equation was validated using FEM methods and digital image correlation impact tests. According to the roll over impact situation, the multi-layered semi-circular corrugated woven CFRP roof panel displays a positive failure behavior of 89%.
