FINITE ELEMENT ANALYSIS OF LASER STITCH WELDED HIGH STRENGTH STEELS FOR AUTOMOTIVE

Author(s):  
Heeseon BANG ◽  
Hansur BANG ◽  
Yoonki LEE ◽  
ChongIn OH ◽  
Chanseung RO
Author(s):  
Matthew G. Dick ◽  
David S. McConnell ◽  
Hans C. Iwand

Screw spikes, also known as coach screws, are an advanced alternative to common cut spikes for track fastening. Despite their ability to secure tie plates with a clamp load and utilization of high strength steels, they are still susceptible to bending fatigue failure from lateral wheel loads. A novel method of measuring these bending loads on screw spikes was developed and implemented to characterize the load environment of the screw spikes. Results indicated that measured peak bending loads under lateral wheel loads reached as high as 10,000 lbs for individual spikes, while others carried no load whatsoever. A finite element model was developed to determine the tensile stress fields created by the measured bending loads. A good correlation was found between the FEA model predicted point of highest stress and the location of fracture. Through the testing and analysis it was determined that lateral wheel loads are not distributed evenly among the four screw spikes of a single tie plate. Instead, it was found that one spike carried nearly no load while the spike opposite of it carried more load. Using the finite element analysis it was determined that the spike exposed to the higher loading was subjected to tensile stresses above its endurance limit, which would eventually lead to a bending fatigue failure.


2012 ◽  
Vol 548 ◽  
pp. 456-460 ◽  
Author(s):  
Gopi Alagappan ◽  
Syed H. Masood ◽  
Xuan Zhi Wang

In sheet metal forming, springback is defined as an elastic material recovery after unloading of the forming tools. Springback causes variations and inconsistencies of final part dimensions. Therefore prediction of springback is very important for production of precise products used in automobile and aerospace industries. There are various parameters involved in the process of sheet metal forming, including Young’s modulus, coefficient of friction, Poisson’s ratio, blank thickness, blank length, die radius, punch radius and blank holder force. The aim of this paper is to investigate the springback of a U-channel part by finite element analysis (FEA) and to identify the influences of important parameters on the springback of advanced high strength steels (AHSS) using numerical simulation.


Author(s):  
Saeid Nasheralahkami ◽  
Weitian Zhou ◽  
Sergey Golovashchenko

Advanced high strength steels (AHSS) and ultra-high strength steels (UHSS) have been increasingly implemented by the automotive industry for better crashworthiness and fuel economy. However, these steels are often sensitive to the trimmed edge cracking. The objective of the present paper is to study the sheared edge of ultra-high strength dual-phase steel, DP980, in mechanical trimming and hole punching by sheared edge quality assessment, stretchability, and hole expansion tests as well as finite element analysis. Furthermore, the mechanism of fracture propagation in trimming and hole punching processes of DP980 was discussed. Rather a unique fracture mechanism was observed for trimming of DP980 steel leading to the burr removal at the final stage of the trimming process. Finite element analysis revealed that, under very large clearances, a secondary crack initiates from the edge of the lower tool, and the primary propagated crack turns toward it simultaneously. Intersecting of these two cracks leads to the total separation and leaves the edge of the trimmed part with a broken burr. Fracture observation of trimmed specimens revealed that crack initiation sites under tension moved from the middle of the trimmed surface toward the burr tip with increasing the clearance. This study demonstrates the importance of stretchability tests for designing the stamping dies as well as a reliable finite element simulation for characterizing the material behavior during the shearing process.


2021 ◽  
Vol 2101 (1) ◽  
pp. 012059
Author(s):  
Z J Yang ◽  
X Li ◽  
G C Li ◽  
S C Peng

Abstract Hollow concrete-filled steel tubular (CFST) member is mainly adopted in power transmission and transformation structures, but when it is used in the superstructure with complex stress, the hollow CFST member has a low bearing capacity and is prone to brittle failure. To improve the mechanical performance of hollow CFST members, a new type of reinforced hollow high strength concrete-filled square steel tube (RHCFSST) was proposed, and its axial compression performance was researched. 18 finite element analysis (FEA) models of axially loaded RHCFSST stub columns were established through FEA software ABAQUS. The whole stress process of composite columns was studied, and parametric studies were carried out to analyze the mechanical performance of the member. Parameters of the steel strength, steel ratio, deformed bar and sandwich concrete strength were varied. Based on the simulation results, the stress process of members can be divided into four stages: elastic stage, elastoplastic stage, descending stage and gentle stage. With the increase of steel strength, steel ratio, the strength of sandwich concrete and the addition of deformed bars, the ultimate bearing capacity of members also increases. Additionally, the increment of those parameters will improve the ductility of the member, except for the sandwich concrete strength.


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