Passive Safety Analysis for the Commercial Vehicle Cab after Weight-Reduction Design

Lighter weight commercial vehicles facilitate faster transport, higher mobility and fuel conservation. Weight reduction and safety are mutually competing objectives. And the safety should not be compromised after weight reduction. Full size crash tests are expensive and time consuming to organize. Using a numerical simulation for predicting crash to the occupants’ safety can minimize the number of such trials. In this paper three virtual crash simulations for the three load cases: Front impact test, Roof strength test and Rear wall strength test are performed according to the European regulation ECE-R29. The explicit finite element program LS-DYNA is used for that purpose. The comparisons between simulation results and test data available in the literature are also presented in this paper.

Distribution of Side Abutment Stress in Roadway Subjected to Dynamic Pressure and Its Engineering Application

The borehole stress-meter was employed in this study to investigate the distribution of the side abutment stress in roadway subjected to dynamic pressure. The results demonstrate that the side abutment stress of the mining roadway reaches a peak value when the distance to the gob is 8 m and the distribution curve of the side abutment stress can be divided into three zones: stress rising zone, stress stabilizing zone, and stress decreasing zone. Further numerical investigation was carried out to study the effect of the coal mass strength, coal seam depth, immediate roof strength, and thickness on the distribution of the side abutment stress. Based on the research results, we determined the reasonable position of the mining roadway and the optimal width of the barrier pillar. The engineering application demonstrates that the retention of the barrier pillar with a width of 5 m along the gob as the haulage roadway for the next panel is feasible, which delivers favorable technological and economic benefits.

The Roof Technology Research for LNG Cryogenic Storage Tank Based on ABAQUS

Based on the structural strength and stability theory, the paper introduce the basic principle and key considerations about the roof structural analysis, especially it should pay more attention to the concrete segment pouring effects. Taking the Tianjin LNG cryogenic storage tank as an example, which is independently finished by CNOOC, The finite element method is used for the roof strength and instability mode analysis, and study the failure sequence of strength damage and instability about the roof shell structure.

Numerical Analysis of Roof Pre-Splitting Roadway Effect in Incline Coal Seam

Roof pre-splitting roadway is a new technology in roof induced rock burst prevention and control of incline coal seam. With the purpose of increasing rock burst prevention and control effective, FLAC3D numerical simulation software was used to analyze stress distribution characteristics and roof pre-splitting effect and the layout of the roof pre-splitting roadway parameters. The results showed that the roof pre-splitting roadway changed roof and floor stress distribution, the stress concentration degree is high in the zone of roof and floor around pre-splitting roadway and the two ribs of pre-splitting roadway, which made the roof strength weakened and easy to break, avoiding a large overhang in the process of mining and rock-burst; The roof pre-splitting roadway led to stress concentration in the range of 5 ~ 10 m, roof effective weakening range 12 m, so the distance of two roof pre-splitting roadway should be more than 20m. The research provided the reference basis for rock burst prevention by roof pre-splitting roadway in the incline coal seam group mining.

Roof Structure Design and Evaluation for Improvement of Roof Strength of Three-Wheel Vehicles

This paper is concerned with auto-body frames and roof structures against rollover motion which could take place frequently with TWVs compared to FWVs because of the major difference of the loading between the two motions. Topology optimization is utilized for conceptual design and preliminary design of the roof structure for various loading conditions. The roof structure for TWV consists of existing part of FWV and a new part called Cross-bar reinforcement. Although a test method for regulation of roof strength is with static loading, simulations are carried out for both static and dynamic cases. In the dynamic loading case, rate-dependency of a material needs to be considered for accurate results of FE analysis.

The Interaction Relationship between Support Setting Load and Surrounding Rock

The interaction relationship between support setting load and surrounding rock is the basis of support selection and surrounding rock control. The paper analyzes the interaction relationship between support setting load and surrounding rock by means of theory and experimental data. It is proved that setting load has an important influence on inhibiting immediate roof caving and enhancing immediate roof strength. The increment of setting load can prevent immediate roof falling. Setting load can affect the supporting body stiffness and distribution range of augmented resistance .The lower of the setting load, the larger of the roof deflection. The paper puts forward calculation method and influencing factors of coal wall stability ratio. According to the pressure date comparison of Tiebei mine two coal faces, setting load is one of important factors inducing roof large area weighting.