Study of Pre-Stress Effect of Ribcage Structure on Chest Response of Crash Dummy Model

2010 ◽  
Author(s):  
Xinghua Lai ◽  
Qing Zhou
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Fe Model ◽  
Stress Effect ◽  
Stress Model ◽  
Test Results ◽  
Hybrid Iii ◽  
Structural Responses ◽  
Stress States

Assembling induced pre-stress state commonly exists in the ribcage structure of Hybrid III dummy hardware. In the practice of dummy modeling, however, the pre-stress issue is often neglected. This study is intended to assess the pre-stress effect on chest response of the Hybrid III 50th percentile male dummy model. In this paper, how the pre-stress state is generated in the dummy ribcage assembling process is first elaborated by disassembling and reverse engineering a physical dummy chest structure. A thorax FE model is then built and validated against test results. Using finite element modeling approach, the structural responses with and without the pre-stress state are compared and analyzed at single rib, ribcage and full dummy levels and under a number of loading conditions. The study has found out that, there are two common pre-stress states existing in the rib components of the dummy ribcage, pre-compressive stress and pre-tensile stress. Compared with no pre-stress model, the pre-compressive stress makes a rib stiffer and the pre-tensile stress makes a rib less stiff. It is further concluded that, the pre-stress effect is significant at the single rib level and insignificant at the ribcage level and the full dummy level. This is mainly because the effects of the pre-compressive stress and the pre-tensile stress existing in the six ribs are compensated each other in the assembled ribcage. Therefore, neglecting the pre-stress effect of the ribcage structure in the dummy models is reasonable.

The Characteristics of the Magnetic Memory Signals under Different States for Q235 Defect Samples

2010 ◽  
Vol 97-101 ◽  
pp. 500-503 ◽  
Author(s):  
Jian Wei Li ◽  
Min Qiang Xu ◽  
Jian Cheng Leng ◽  
Ming Xiu Xu
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Magnetic Behavior ◽  
Ferromagnetic Materials ◽  
Magnetic Memory ◽  
Testing Environment ◽  
Memory Signals ◽  
Stress States ◽  
Testing Environments ◽  
Different Characteristics

Magnetic behavior of ferromagnetic materials has been using to detect defects of materials. To evaluate the stress states of the components by the magnetic memory signal, Q235 defect asymmetrical samples were made. The characteristics of magnetic memory of Q235 have been studied in the three different testing environments which are online-loading, online-unloading and offline-unloading under cycle tensile stress. The results show that magnetic memory signals have different characteristics in different testing environment. It is feasible to evaluate preliminarily the stress state by the magnetic memory signals.

Low Cycle Fatigue Crack Initiation of Rotating Structures Under Biaxial Stress States

2009 ◽  
Author(s):  
Chao Zhang
Keyword(s):  
Stress State ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Biaxial Stress ◽  
Test Results ◽  
Primary Stress ◽  
Biaxial Stress State ◽  
Fatigue Characteristics ◽  
Stress States

Rotating structures can experience biaxial stress states with a wide range of biaxiality ratios on structure surfaces. Low cycle fatigue (LCF) crack initiation in such conditions demonstrates different fatigue characteristics in terms of crack orientation, fatigue life, etc. The biaxial stress states can be categorized into two types: in-phase and out-of-phase under which fatigue characteristics can be significantly different according to rig test results. This paper presents an investigation of LCF crack initiation under in-phase and out-of-phase biaxial stress states based on rig test results of a nickel alloy. The crack orientations are reviewed and discussed at different stress states. Relations of biaxial LCF life debit factor vs biaxiality ratio are derived (the debit factor is defined as a ratio of the LCF life at a biaxial stress state to the LCF life at corresponding uniaxial stress state which has same cyclic and mean stresses as the primary cyclic and mean stressees of the biaxial stress state). The rig test results showed that the crack orientation is usually normal to the primary stress vector under in-phase biaxial stress states but is inclined to the primary stress vector under out-of-phase stress states. As per the derived biaxial LCF life debit factors, the LCF life was found to be slightly reduced with increasing biaxiality ratios under in-phase biaxial stress states but significantly reduced under out-of-phase biaxial stress states compared with corresponding uniaxial primary stress states. The equivalent cyclic stress fatigue criterion is also employed to theoretically model the biaxial LCF life debit factor under in-phase biaxial stress states. The hydrostatic cyclic stress is included in the equivalent cyclic stress in order to take into account the hydrostatic cyclic pressure effects. The equivalent cyclic stress in the criterion can physically reflect the materials’ ductility reduction under in-phase multiaxial stress states.

Fundamental mechanical behaviors of dental restorative materials resin composites due to compressive and flexural loading and internal damage evaluation

2015 ◽  
Vol 26 (6) ◽  
pp. 826-839 ◽  
Author(s):  
Mamoru Mizuno
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Resin Composites ◽  
Compression Tests ◽  
Mechanical Behaviors ◽  
Stress Strain ◽  
Internal Damage ◽  
Bending Tests ◽  
Three Point Bending

Development of internal damage within resin composites was evaluated under compressive loading in order to predict crack initiation and fracture. Moreover, three-point bending tests were also carried out in order to clarify mechanical behavior and fracture under tensile stress state in comparison with those under compressive stress state. Both of them were conducted for the purpose of obtaining data to formulate constitutive equations for resin composites and to implement precise numerical simulation. Columnar specimens for compression tests and square pole specimens for three-point bending tests were prepared by using clinical resin composites. In compression tests, loading–unloading (or –reloading) was given to columnar specimens and Young’s modulus was evaluated by the gradient of stress–strain curves under unloading. Internal damage was evaluated from the variation of Young’s modulus as a scalar damage variable based on the continuum damage mechanics. The variation of apparent density and residual strain at vanished stress were also discussed in association with the development of internal damage. Accumulation of internal damage was found on the stress–strain curve under loading–unloading–reloading in comparison with the curve under monotonic loading. On the other hand, in three-point bending tests, dependence of stress–strain curves on light curing time and strain rate was clarified. Since compression tests have been carried out under similar experimental conditions by authors so far, mechanical behaviors of resin composites under tensile stress state were discussed in comparison with those under compressive stress state. Brittleness under tensile stress state was indicated in comparison with compressive stress state.

Effects of initial stress state on the subsurface stress distribution after ultrasonic impact treatment on thick specimens

2020 ◽  
pp. 030932472097683
Author(s):  
Chuan Liu ◽  
Jiabin Shen ◽  
Changhua Lin ◽  
Jianfei Wang ◽  
Jianxin Wang
Keyword(s):  
Stress State ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Initial Stress ◽  
Correction Method ◽  
Welding Residual Stress ◽  
Initial Stress State ◽  
Ultrasonic Impact Treatment ◽  
Before And After

Thick welded specimens with different initial stress states were prepared and treated with the ultrasonic impact treatment (UIT). The subsurface stresses before and after UIT were measured by the X-ray diffraction (XRD) method combined with layer removal. The measured results were corrected based on the finite element correction method. The effects of initial high tensile stress and low compressive stress on the in-depth after-UIT stress distributions were investigated. The results show that initial stress has no effects on the stresses induced by the UIT within 1 mm depth and within that depth, UIT can induce almost the same longitudinal and transverse stress curves beneath the surface with a peak compressive stress close to the material yield strength at the depth of near 0.6 mm and 0.8 mm. UIT induces almost the same longitudinal and transverse stresses along with the measured depth under initial low compressive stress state. While under the initial high tensile stress state, the initial stress dominates the final stress distribution over 1 mm depth. Initial high tensile stress (welding residual stress) can reduce the depth of the after-UIT compressive stresses to 62.5% to 75% of that under the initial low-compressive stress state.

Optimal Matching of Processing Parameters of Horizontal V-Shaped Anvils for Heavy Axial Forgings Manufacturing

2011 ◽  
Vol 52-54 ◽  
pp. 2170-2175
Author(s):  
B. Li ◽  
J. Yu ◽  
Suo Qing Yu ◽  
A.B. Wang ◽  
Y.H. Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Theoretical Foundation ◽  
Axial Stress ◽  
Processing Parameters ◽  
Middle Part ◽  
Reduction Ratio ◽  
Width Ratio ◽  
Stress States

The forging method with horizontal V-shaped anvils (HVA) is effective in the control of inner stress states, metal tissue, etc. FEM numerical simulation is conducted for the HVA forging method, under various processing parameters. The results show that during HVA forging, the transversal and axial stress states in the middle part of forgings are influenced by not only the ratio of the anvil width to billet height (anvil-width ratio )but also the ratio of the blank width to billet height (blank-width ratio) and the reduction ratio, while the end parts are influenced little. Among those processing parameters, the reduction ratio plays an important role. When the reduction ratio is 5% or 10%, it is possible to obtain axial and transversal tensile stress. When the reduction ratio is larger than 15%, it is easy to obtain two-way compressive stress. Therefore, in order to control the two-way tensile stress, big reduction ratio should be adopted. Small blank-width ratios result in the forgings cracks because of transversal tensile stress in common flat-anvil stretching method. On the contrary, even if the blank-width ratio is small, transversal compressive stress can be generated in forgings for the HVA forging method, only if the matching of the anvil-width ratio and the reduction ratio is suitable. The feature of the HVA forging method benefits the preventing forgings from inner cracks. The results provide the theoretical foundation for the application of the HVA forging method.

scholarly journals Static Analysis of a Tire Sidewall Developed From Tailored Organomodified Kaolin/Natural Rubber Vulcanizates

2017 ◽  
Vol 1 (2) ◽  
pp. 106
Author(s):  
Chinedum Ogonna Mgbemena ◽  
ThankGod Enatimi Boye ◽  
Ikuobase Emovon
Keyword(s):  
Tensile Stress ◽  
Natural Rubber ◽  
Principal Stress ◽  
Compressive Stress ◽  
Filler Loading ◽  
Elastic Behavior ◽  
Shear Stresses ◽  
Fe Model ◽  
Creative Commons ◽  
Automobile Tire

This paper is on the prediction of stress limits and strain distributions of an automobile tire sidewall developed from Natural Rubber (NR)/Tea Seed Oil (TSO) modified kaolin composites. The stress-strain data report of NR/TSO modified kaolin at filler loading of 10phr was used to establish parameters characterizing the elastic behavior of the rubber vulcanizates. The tire model investigated was developed from MATLAB PDE Toolbox. The study was developed on maximum inflation pressure of 0.220632 MPa. The 2D Finite Element (FE) model computations for static loading of the tire sidewall gave a reasonable prediction of the stress limits and strain distributions, as the shear stresses obtained were within the range of −10 MPa to 10 MPa. The strain energy distributions were found to be within the range of −1500 J·m−3 to 1500 J·m−3. The stress limits for the first principal stress with respect to their magnitudes and orientations was obtained as 10 MPa for tensile stress and −20 MPa for compressive stress respectively while the stress limits for the second principal stress was obtained as 20 MPa for tensile stress and −10 MPa for compressive stress. The plane stress analysis with MATLAB PDE Toolbox gave stress limits distribution in terms of von-Mises stresses in the range 5 MPa - 25 MPa. The results indicate that NR/TSO modified kaolin composites can be employed in automobile tire sidewall applications.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

scholarly journals Effects of pile material and loading state on adhesive strength of piles in ice

1983 ◽  
Vol 20 (4) ◽  
pp. 673-680 ◽  
Author(s):  
R. Frederking ◽  
J. Karri
Keyword(s):  
Stress State ◽  
Compressive Stress ◽  
Adhesive Strength ◽  
Laboratory Tests ◽  
Test Series ◽  
Coated Steel ◽  
Special Test ◽  
Relative Stiffness ◽  
Concrete Piles ◽  
Stress States

Laboratory tests on piles made of different materials (polyethylene, polyvinylchloride, steel, wood, concrete, and Inerta 160-coated steel) were used to investigate their adhesion to an ice cover at high rates of loading. Steel, wood, and concrete piles had adhesive strengths from 0.4 to 0.5 MPa; failure at these stresses occurred in the ice. Polyethylene and polyvinylchloride piles had an adhesive strength in the range 0.05–0.07 MPa; failure was characterized by separation between the pile and the ice. Inerta 160-coated steel had an intermediate strength of 0.25 MPa. Measured strengths were related both to the adhesion of ice to the pile and compliance of the pile. A special test series investigated the effect on adhesion of a tensile or compressive stress state in a polyethylene pile. An adhesive strength of 0.06 MPa was recorded in tension, and 0.13 MPa in compression, because of the relative stiffness of the pile and the ice. Keywords: ice loading, piles, ice adhesion, pile material, stress states.

scholarly journals Analysis on stress state of box-girder web under prestressing effect

2018 ◽  
Vol 17 ◽  
pp. 03007
Author(s):  
Haijun Yin ◽  
Ziqing Li ◽  
Xianwu Hao ◽  
Baojun Zhao
Keyword(s):  
Tensile Stress ◽  
Compressive Stress ◽  
Cross Section ◽  
Neutral Axis ◽  
Curved Beam ◽  
Stress Effect ◽  
Box Girder ◽  
Principal Tensile Stress ◽  
Bending Radius ◽  
The Web

In order to study the effect of prestressed box girder webs stresss state, determining the stress distribution within a web, research and analysis of vertical prestressed box girder, curved beam prestressed sensitivity under the web. Establishing the finite element model of the box girder web vertical prestressing effect is analyzed, results show that the principal tensile stress of the web is sensitive to the vertical prestress, applying the vertical prestress can effectively reduce the principal tensile stress of the web; with the decrease of the effective vertical prestress, the neutral axis above the principal compressive stress decreases rapidly, while below the neutral axis decreases relatively slow; Under the same vertical preloading stress level, the roots of cross section of the compressive stress of web reserves than L / 4 section of the web. Calculation and analysis of curved beam under bending point, different bending angles and bending radius of principal stress effect on the web, Results show that the set of curved beam web when the curved beam bending stress concentration easily, appear the main tensile stress; Increase the bending radius can effectively reduce beam cross-section of web principal tensile stress, along with the rising of the next corner, principal tensile stress peak value increases gradually, thus setting bending beam, should try to reduce the bending angle.

Study on Normal Section Bearing Capacity of Stone Arch Rib Enclosed by Reinforced Concrete

2012 ◽  
Vol 594-597 ◽  
pp. 1565-1568
Author(s):  
Jing Zhang ◽  
Yong Jiu Qian
Keyword(s):  
Reinforced Concrete ◽  
Stress State ◽  
Mechanical Behavior ◽  
Bearing Capacity ◽  
Failure Mechanism ◽  
Analytical Method ◽  
Influence Factors ◽  
Test Results ◽  
Normal Section ◽  
Stress States

The mechanical behavior and failure mechanism of stone arch rib enclosed by reinforced concrete under different existed stress state is obtained by the failure test. Normal section bearing capacity effect of different stress states is studied by test results. Then an analytical method considering the influence factors is proposed to count normal section bearing capacity of stone arch rib enclosed by reinforced concrete.

scholarly journals Earth Pressure of Three-Dimensional Stress States under Different Strength Criteria and Its Application

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yu Zhang ◽  
Jin Liu ◽  
Te-Jia Fan ◽  
Chen-Yang Xu ◽  
Tian-Yi Meng ◽  
...  
Keyword(s):  
Stress State ◽  
Principal Stress ◽  
Three Dimensional ◽  
Earth Pressure ◽  
Measured Data ◽  
Intermediate Principal Stress ◽  
Stress Effect ◽  
Passive Earth Pressure ◽  
The Earth ◽  
Stress States

To solve the Earth pressure problems in practical engineering, such as retaining walls and foundation pits, we derive active and passive Earth pressure formulas in accordance with the relationship between intermediate principal stress and excavation under three-dimensional stress states. The formulas are derived on the basis of the Mohr–Coulomb, spatially mobilized plane (SMP), σ 3 SMP, Lade–Duncan, axisymmetric compression- (AC-) SMP strength, and generalized Mises (Gen-Mises) criteria and then extended to clay. We also compare the calculated Earth pressure with the measured data. Results indicate that the Earth pressure considering medium principal stress contribution under a three-dimensional stress state is consistent with the actual engineering. The calculated active Earth pressure in the Mohr–Coulomb strength criterion is larger, and the passive Earth pressure is smaller than the practical one because the intermediate principal stress effect is not considered. The calculated results of the SMP, σ 3 SMP, Lade–Duncan, AC-SMP strength, and Gen-Mises criteria are close to the measured data, among which the result of the Gen-Mises criterion is closer. The Earth pressure calculated using the Lade–Duncan criterion is no longer appropriate to describe the Earth pressure under medium principal stress condition in this study. The results of this study have theoretical significance for retaining structure design under a three-dimensional stress state.

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