Effect of different lapping orders on mechanical performance and nugget forming process for three-sheet dissimilar resistance spot welding joints between DC06 and unequal-thickness hot-stamped B1500HS steel sheets

2021 ◽  
Vol 118 (1) ◽  
pp. 112
Author(s):  
Xin Mao ◽  
Zhi Cheng ◽  
Qiang Zhu ◽  
Wurong Wang ◽  
Xicheng Wei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Formation Mechanism ◽  
Mechanical Performance ◽  
Peak Load ◽  
Element Model ◽  
Type I ◽  
Type Ii ◽  
Forming Process ◽  
Pull Out ◽  
Nugget Formation

In this study, the mechanical properties of two welded joints under different lapping orders (B1500HS-1.4 mm/B1500HS-1.6 mm/DC06, denoted as type I; B1500HS-1.4 mm/DC06/B1500HS-1.6 mm, denoted type II) were compared. The nugget formation mechanism was analysed by a coupled electrical-thermal finite element model (FEM). It is found that different lapping orders significantly affect the mechanical properties of three-sheet RSW joints. All RSW joints tend to fail in the pull-out or tearing failure mode. The peak load of the two interfaces of type II RSW joint is more balanced, and the failure load of which is much higher than that of the type I RSW joint; The warpage was observed at type I welded joint. Considered the load-carrying capacity, type II was excellent. The simulation results indicate that the diameter of the weld nugget at the upper interface of the type I RSW joint was larger than that on the other interfaces, which agree well with the experimental results. The nugget formation mechanism of dissimilar high strength steel three-sheet RSW joint was obtained that forming the nugget firstly from two interfaces and final formed nuggets were asymmetric.

scholarly journals Microstructure and Mechanical Performance of Resistance Spot Welded Martensitic Advanced High Strength Steel

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1021
Author(s):  
Yunzhao Li ◽  
Huaping Tang ◽  
Ruilin Lai
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Strong Dependence ◽  
High Strength ◽  
Weld Nugget ◽  
Resistance Spot ◽  
Pull Out ◽  
Cross Tension ◽  
Spot Welded

Resistance spot welded 1.2 mm (t)-thick 1400 MPa martensitic steel (MS1400) samples are fabricated and their microstructure, mechanical properties are investigated thoroughly. The mechanical performance and failure modes exhibit a strong dependence on weld-nugget size. The pull-out failure mode for MS1400 steel resistance spot welds does not follow the conventional weld-nugget size recommendation criteria of 4t0.5. Significant softening was observed due to dual phase microstructure of ferrite and martensite in the inter-critical heat affected zone (HAZ) and tempered martensite (TM) structure in sub-critical HAZ. However, the upper-critical HAZ exhibits obvious higher hardness than the nugget zone (NZ). In addition, the mechanical properties show that the cross-tension strength (CTS) is about one quarter of the tension-shear strength (TSS) of MS1400 weld joints, whilst the absorbed energy of cross-tension and tension-shear are almost identical.

Some discriminatory characteristics of earthquakes near the Kariba, Kremasta, and Koyna artificial lakes

1972 ◽  
Vol 62 (2) ◽  
pp. 493-507 ◽  
Author(s):  
Harsh K. Gupta ◽  
B. K. Rastogi ◽  
Hari Narain
Keyword(s):  
Mechanical Properties ◽  
Time Distribution ◽  
Focal Mechanisms ◽  
Type I ◽  
Type Ii ◽  
B Values ◽  
Artificial Lakes ◽  
Earthquake Sequences ◽  
Frequency Magnitude

abstract The behavior of earthquakes near the artificial lakes at Kariba, Kremasta, and Koyna, where earthquakes of magnitude exceeding 6 have occurred, is examined. Foreshock-aftershock patterns of these earthquake sequences correspond with Mogi's type II model, whereas the normal earthquakes of these regions belong to type I. Three similar relations could be fitted in the time distribution of aftershocks of the main earthquakes. Quite contrary to normal earthquakes, foreshock b values are found to be comparable with the aftershock b values in the frequency-magnitude relations. Focal mechanisms of the largest earthquakes of these sequences have been determined and compared. Dip-slip components of the motion are such that the lakes are situated on the downthrown blocks. These regions are characterized by a volcanic past and the presence of rocks such as limestones and red boles which are easily affected by water. These findings are useful in distinguishing the reservoir-associated earthquakes from normal earthquakes and suggest that the artificial lakes are responsible for changing the mechanical properties of the strata and releasing the accumulated strains.

scholarly journals Mechanical performance of HMA-2 modified with purified and unpurified carbon nanotubes and nanofibers

2017 ◽  
Vol 37 (2) ◽  
pp. 99-106
Author(s):  
Mario Rodrigo Rubio ◽  
Duván Julián Martínez ◽  
Carlos Enrique Daza ◽  
Fredy Alberto Reyes
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Elastic Modulus ◽  
Mechanical Performance ◽  
Resilient Modulus ◽  
Type Ii ◽  
Dynamic Characterization ◽  
Traffic Loads ◽  
Nickel Copper

The present study evaluates the mechanical performance of a Hot Mix Asphalt – Type II (HMA-2) modified with carbon nanotubes and carbon nanofibers (CNTF). CNTF were made by means the Catalytic Vapor Deposition (CVD) technique at 700° C using a Nickel, Copper and Aluminum (NiCuAl) catalyst with a Cu/Ni molar relation of 0,33. In order to properly assess HMA-2 performance, three different mixtures were analyzed: 1) HMA-2 modified with purified CNTF; 2) HMA-2 modified with non-purified CNTF and, 3) a Conventional HMA-2 (control). Samples manufactured in accordance with the Marshall Mix Design were tested in the laboratory to study rutting, resilient modulus (Mr) and fatigue. In addition to the aforementioned dynamic characterization, the effect of CNTF purification on the asphalt mixture’s mechanical properties was analyzed. In short, a comparative study was designed to determine whether or not CNTF should be purified before introduction into the HMA-2. This investigation responds to the growing demand for economical materials capable of withstanding traffic loads while simultaneously enhancing pavement durability and mechanical properties. Although purified CNTF increased HMA-2 stiffness and elastic modulus, non-purified CNTF increased the asphalt mixture’s elastic modulus without considerable increases in stiffness. Thus, the latter modification is deemed to help address fatiguerelated issues and improve the long-term durability of flexible pavements.

The Effects of Operational, Testing and Material Characterisations On the Change in Yield Strength From Plate to Pipe

2021 ◽  
Author(s):  
Jingsi Jiao ◽  
Cheng Lu ◽  
Valerie Linton ◽  
Frank Barbaro
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Yield Strength ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Element Model ◽  
Critical Knowledge ◽  
Operational Testing ◽  
Wide Range ◽  
The Individual

Abstract The mechanical performance of the pipe sample has a direct influence on their application in real environments and a significant economic impact on manufacturers, especially when the pipe products do not meet required specifications. There is often a change in the yield strength from plate to pipe due to strain hardening and the Bauschinger effect. The current work sets out to provide a critical knowledge base for this change, with emphasizing the important influence of the plate mechanical properties on the pipe. So that the quality of pipe can be further ensured. In the work, firstly, the historical data of the pipe yield strength were collected and plotted together from a wide range of published sources to provide a broad quantitative insight, which provides a quantitative review on the parameters that govern the final pipe yield strength. Secondly, a Finite Element model of the pipe forming and mechanical evaluation was developed and then validated with available industrial testing results, in where the effects of operational and testing parameters on the pipe yield strength were analysed and discussed in detail. Finally, using the validated Finite Element model, a parametric study was conducted to dissect the individual role that each of the material parameters plays on changing the yield strength from plate to pipe. We found that the yield strength of the pipe can differ significantly. This work sheds lights on the desired plate mechanical properties to optimize the final pipe yield strength.

Three Point Bend Performance of Solutionized, Die Quenched and Heat Treated AA7075 Beam Members

2014 ◽  
Vol 794-796 ◽  
pp. 431-436 ◽  
Author(s):  
Alexander Bardelcik ◽  
Alexandre Bouhier ◽  
Michael J. Worswick
Keyword(s):  
Mechanical Properties ◽  
Peak Load ◽  
Natural Aging ◽  
High Strength ◽  
Total Elongation ◽  
Strength Properties ◽  
Heat Treatments ◽  
Forming Process ◽  
Heat Treated ◽  
Point Bend

To overcome the low room temperature formability of AA7075-T6 aluminum sheet, without sacrificing the high strength properties of this alloy, a hat section beam member was formed and quenched within a cold die immediately after a 20 minute solutionizing treatment. Natural aging for 24 hours followed the forming process which was then followed by various heat treatments that included a typical precipitation hardening (PH) and industrial paint bake (PB) temperature-time treatment. Tensile specimens were extracted from the beams to evaluate their mechanical properties. When compared to the as-received AA7075-T6 mechanical properties, the beams heat treated with the PH, PHPB and PB treatment resulted in a 5%, 13% and 20% reduction in ultimate tensile strength respectively. A similar trend was shown for the yield strength measurements. There was little effect of the heat treatments on the total elongation, with the PH condition showing a slight improvement. A backing plate was riveted to the beams and a quasi-static 3 point bend test was conducted to evaluate the crush performance. The peak load for the PH, PHPB and PB beams was 9.2, 8.5 and 7.3 kN respectively, but the calculated energy-displacement (or energy absorption) curves were similar for the PH and PHPB parts due to a more ductile fracture behavior for the PHPB material condition.

scholarly journals Preliminary Deformational Studies on a Finite Element Model of the Nasal Septum Reveals Key Areas for Septal Realignment and Reconstruction

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Kyrin Liong ◽  
Shu Jin Lee ◽  
Heow Pueh Lee
Keyword(s):  
Nasal Septum ◽  
Preoperative Planning ◽  
Three Dimensional ◽  
Element Model ◽  
Septal Cartilage ◽  
Type I ◽  
Type Ii ◽  
Anterior Nasal Spine ◽  
Force Direction ◽  
Three Dimensional Models

Background. With the current lack of clinically relevant classification methods of septal deviation, computer-generated models are important, as septal cartilage is indistinguishable on current imaging methods, making preoperative planning difficult. Methods. Three-dimensional models of the septum were created from a CT scan, and incremental forces were applied. Results. Regardless of the force direction, with increasing force, the septum first tilts (type I) and then crumples into a C shape (type II) and finally into an S shape (type III). In type I, it is important to address the dislocation in the vomer-ethmoid cartilage junction and vomerine groove, where stress is concentrated. In types II and III, there is intrinsic fracture and shortening of the nasal septum, which may be dislocated off the anterior nasal spine. Surgery aims to relieve the posterior buckling and dislocation, with realignment of the septum to the ANS and possible spreader grafts to buttress the fracture sites. Conclusion. By identifying clinically observable septal deviations and the areas of stress concentration and dislocation, a straighter, more stable septum may be achieved.

scholarly journals A non-associative macro-element model for vertical plate anchors in clay

2021 ◽  
Author(s):  
Anderson Peccin da Silva ◽  
Andrea Diambra ◽  
Dimitrios K. Karamitros ◽  
Shiao Huey Chow
Keyword(s):  
Peak Load ◽  
Element Model ◽  
Offshore Structures ◽  
Model Parameters ◽  
Hardening Rule ◽  
Pull Out ◽  
Proposed Model ◽  
Plastic Potential ◽  
Plastic Hardening ◽  
Macro Element

This work proposes a new plastic hardening, non-associative macro-element model to predict the behaviour of anchors in clay for floating offshore structures during keying and up to the peak load. Building on available models for anchors, a non-associated plastic potential is introduced to improve prediction of anchor trajectory and loss of embedment at peak conditions for a large range of padeye offsets and different pull-out directions. The proposed model also includes a displacement-hardening rule to simulate the force and displacement mobilisation at the early stages of the keying process. The model is challenged and validated against different sets of numerical and centrifuge data. This extensive validation process revealed that two of the four newly introduced model parameters assume a constant value for the range of simulated cases. This suggests that only two of the newly introduced parameters may need to be calibrated for the use of the proposed macro-element model in practice.

scholarly journals EFFECT OF OIL PALM FIBRES VOLUME FRACTION ON MECHANICAL PROPERTIES OF POLYESTER COMPOSITES

2010 ◽  
Vol 24 (23) ◽  
pp. 4459-4470 ◽  
Author(s):  
B. F. YOUSIF
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Oil Palm ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Single Fibre ◽  
Volume Fractions ◽  
Pull Out ◽  
Polyester Composite ◽  
Polyester Composites

The effect of two types of oil palm fibres (bunch and fruit) on mechanical properties of polyester composites is examined in the current work considering different volume fractions. Tensile, compression, and flexural properties of the composites were investigated. In addition to that, tensile strengths were calculated theoretically using Hirsch model. Scanning electron microscope (SEM) was used to observe the fracture mechanism of the specimens. Single fibre pull-out tests were performed to determine the interfacial shear strength between polyester resin and both types of oil palm fibres. Results revealed that both types of oil palm fibres enhanced the mechanical performance of polyester composites. At a higher volume fraction (40–50%), tensile strength of the polyester composite was improved, i.e., 2.5 times improvement in the tensile strength value. Experimental tensile strength values of oil palm bunch/polyester composites have a good correlation with the theoretical results, especially at low volume fractions of fibre. Flexural strength of polyester worsened with oil palm fibres at all volume fractions of fibre.

Formation of Cutting Direction Burr/Fracture in Orthogonal Cutting

2012 ◽  
Vol 426 ◽  
pp. 73-76 ◽  
Author(s):  
Hai Jun Qu ◽  
Gui Cheng Wang ◽  
Y.M Zhu ◽  
Q.X Shen
Keyword(s):  
Mechanical Properties ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Material Failure ◽  
Forming Process ◽  
Fracture Formation ◽  
Edge Quality ◽  
Simulation Results ◽  
And Performance ◽  
Cutting Direction

Cutting direction burr/fracture is one of the important factors that influence the edge quality and performance of precision parts. A finite element model based on material failure mode is developed in this study to simulate the burr /fracture forming process. According to workpiece materials deformation and mechanical properties from the simulation results, the cutting direction burr/fracture formation process is analyzed. The cutting direction burr forms when there is a crack in the area near the tool tip and grow along the principal shear zone, the cutting direction fracture forms as the crack grow along negative zone.

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