scholarly journals Dynamic Response Mechanism of Thin-Walled Metallic Defensive Structure from Explosion in Transportation

2020 ◽  
Author(s):  
Shujian Yao ◽  
Nan Zhao ◽  
Duo Zhang ◽  
Zhonggang Wang ◽  
Zhen Chen
Keyword(s):  
Dynamic Response ◽  
Steel Plate ◽  
Plastic Hinge ◽  
Experimental Studies ◽  
Central Area ◽  
Dynamic Responses ◽  
Image Correlation ◽  
Blast Loads ◽  
Response Mechanism ◽  
Defensive Structure

Defensive structure is important in transportation field for kinds of intentional or unintentional explosion. Structures subjected to unconfined and confined explosion will bear different blast loads and their dynamic responses are different. The present work focus on the dynamic response mechanism of steel plate under unconfined and confined blast loads through both numerical and experimental studies. In the experiment, Digital Image Correlation (DIC) technique was applied to record and analyze the dynamic response process of large-scale field blast test. The DIC measured curve and the numerical calculated curves agrees well in both the trends and the peak values. Then, the dynamic response mechanism of steel plate under unconfined blast (UB) load and confined blast (CB) load were compared and discussed. Results show that the dynamic response of plate can be divided into three phases under both UB and CB loads, while with different mechanism. In phase I, plastic hinge starts from the center and moves to the boundary in UB condition, while in case of CB, plastic hinge occurs close to the boundary and moves in the opposite direction. In phase II, two plastic hinge lines propagates towards each other, and a platform exists between the boundary and the central area remains undeformed in UB condition, while in CB condition, larger deformation in peripheral region rather than central area produces.

Experimental Studies of Sedimentation Basin Dynamics

1977 ◽  
Vol 12 (1) ◽  
pp. 77-90
Author(s):  
J.F. Cordoba-Molina ◽  
P.L. Silveston ◽  
R. R. Hudgins
Keyword(s):  
Dynamic Response ◽  
Froude Number ◽  
Flow Model ◽  
Experimental Studies ◽  
Densimetric Froude Number ◽  
Number Range ◽  
The Real ◽  
Highly Correlated ◽  
Sedimentation Basins ◽  
Simple Flow

Abstract A simple Flow Model is proposed to describe the dynamic response of sedimentation basins. The response predicted by this model is linear as opposed to the real response of the basin which is nonlinear. However, the real response of the basin is highly correlated with its densimetric Froude number, and as a consequence our linear model effectively predicts the response of the basin in a restricted densimetric Froude Number range. Our experiments show that the response of the basin becomes more sluggish and erratic as the densimetric Froude number decreases.

Dynamic response of graded PVC foam sandwich panel under air blast loads

2021 ◽  
pp. 1-15
Author(s):  
Lihong Yang ◽  
Xuyang Li ◽  
Fan Zi ◽  
Shijie Yang ◽  
Zexu Zhang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Sandwich Panel ◽  
Blast Loads ◽  
Air Blast

scholarly journals PacBio full-length transcriptome of wild apple (Malus sieversii) provides insights into canker disease dynamic response

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xiaojie Liu ◽  
Xiaoshuang Li ◽  
Xuejing Wen ◽  
Yan Zhang ◽  
Yu Ding ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Early Response ◽  
Full Length ◽  
Differentially Expressed ◽  
Late Response ◽  
Response Mechanism ◽  
Necrotrophic Pathogen ◽  
Canker Disease ◽  
Malus Sieversii ◽  
Highly Correlated

Abstract Background Valsa canker is a serious disease in the stem of Malus sieversii, caused by Valsa mali. However, little is known about the global response mechanism in M. sieversii to V. mali infection. Results Phytohormone jasmonic acid (JA) and salicylic acid (SA) profiles and transcriptome analysis were used to elaborate on the dynamic response mechanism. We determined that the JA was initially produced to respond to the necrotrophic pathogen V. mali infection at the early response stage, then get synergistically transduced with SA to respond at the late response stage. Furthermore, we adopted Pacific Biosciences (PacBio) full-length sequencing to identify differentially expressed transcripts (DETs) during the canker response stage. We obtained 52,538 full-length transcripts, of which 8139 were DETs. Total 1336 lncRNAs, 23,737 alternative polyadenylation (APA) sites and 3780 putative transcription factors (TFs) were identified. Additionally, functional annotation analysis of DETs indicated that the wild apple response to the infection of V. mali involves plant-pathogen interaction, plant hormone signal transduction, flavonoid biosynthesis, and phenylpropanoid biosynthesis. The co-expression network of the differentially expressed TFs revealed 264 candidate TF transcripts. Among these candidates, the WRKY family was the most abundant. The MsWRKY7 and MsWRKY33 were highly correlated at the early response stage, and MsWRKY6, MsWRKY7, MsWRKY19, MsWRKY33, MsWRKY40, MsWRKY45, MsWRKY51, MsWRKY61, MsWRKY75 were highly correlated at the late stage. Conclusions The full-length transcriptomic analysis revealed a series of immune responsive events in M. sieversii in response to V. mali infection. The phytohormone signal pathway regulatory played an important role in the response stage. Additionally, the enriched disease resistance pathways and differentially expressed TFs dynamics collectively contributed to the immune response. This study provides valuable insights into a dynamic response in M. sieversii upon the necrotrophic pathogen V. mali infection, facilitates understanding of response mechanisms to canker disease for apple, and provides supports in the identification of potential resistance genes in M. sieversii.

scholarly journals Experimental and Numerical Investigation on the Perforation Resistance of Double-Layered Metal Shield under High-Velocity Impact of Armor-Piercing Projectiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes
Keyword(s):  
High Strength Steel ◽  
Steel Plate ◽  
Experimental Studies ◽  
Practical Interest ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Transportation Systems ◽  
Metal Shield ◽  
Softening Parameter

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.

Dynamic response of axially constrained plastic beams to blast loads

1987 ◽  
Vol 23 (1) ◽  
pp. 153-174 ◽  
Author(s):  
R. Vaziri ◽  
M.D. Olson ◽  
D.L. Anderson
Keyword(s):  
Dynamic Response ◽  
Blast Loads

3-D elastic coupling vibration and acoustical radiation characteristics of cracked gear under elastic support condition

2015 ◽  
Vol 23 (9) ◽  
pp. 1548-1568 ◽  
Author(s):  
Shao Renping ◽  
Purong Jia ◽  
Xiankun Qi
Keyword(s):  
Dynamic Response ◽  
Support System ◽  
Three Dimensional ◽  
Elastic Support ◽  
Dynamic Responses ◽  
Tooth Root ◽  
Support Condition ◽  
Elastic Boundary ◽  
Root Crack ◽  
Elastic Disc

According to the actual working condition of the gear, the supporting gear shaft is treated as an elastic support. Its impact on the gear body vibration is considered and investigated and the dynamic response of elastic teeth and gear body is analyzed. On this basis, the gear body is considered as a three-dimensional elastic disc and the gear teeth are treated as an elastic cantilever beam. Under the conditions of the elastic boundary (support shaft), combining to the elastic disk and elastic teeth, the influence of three-dimensional elastic discs on the meshing tooth response under an elastic boundary condition is also included. A dynamic model of the gear support system and calculated model of the gear tooth response are then established. The inherent characteristics of the gear support system and dynamics response of the meshing tooth are presented and simulated. It was shown by the results that it is correct to use the elastic support condition to analyze the gear support system. Based on the above three-dimensional elastic dynamics analysis, this paper set up a dynamics coupling model of a cracked gear structure support system that considered the influence of a three-dimensional elastic disc on a cracked meshing tooth under elastic conditions. It discusses the dynamic characteristic of the cracked gear structure system and coupling dynamic response of the meshing tooth, offering a three-dimensional elastic body model of the tooth root crack and pitch circle crack with different sizes, conducting the three-dimensional elastic dynamic analysis to the faulty crack. ANSYS was employed to carry out dynamic responses, as well as to simulate the acoustic field radiation orientation of a three-dimensional elastic crack body at the tooth root crack and pitch circle with different sizes.

Evaluation of the Dynamic-Response-Based Intact Stability Criterion for Floating Wind Turbines

2015 ◽  
Author(s):  
Marco Masciola ◽  
Xiaohong Chen ◽  
Qing Yu
Keyword(s):  
Wind Speed ◽  
Dynamic Response ◽  
Wind Turbines ◽  
Stability Criterion ◽  
Area Ratio ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Stability Criteria ◽  
Intact Stability ◽  
Overturning Moment

As an alternative to the conventional intact stability criterion for floating offshore structures, known as the area-ratio-based criterion, the dynamic-response-based intact stability criteria was initially developed in the 1980s for column-stabilized drilling units and later extended to the design of floating production installations (FPIs). Both the area-ratio-based and dynamic-response-based intact stability criteria have recently been adopted for floating offshore wind turbines (FOWTs). In the traditional area-ratio-based criterion, the stability calculation is quasi-static in nature, with the contribution from external forces other than steady wind loads and FOWT dynamic responses captured through a safety factor. Furthermore, the peak wind overturning moment of FOWTs may not coincide with the extreme storm wind speed normally prescribed in the area-ratio-based criterion, but rather at the much smaller rated wind speed in the power production mode. With these two factors considered, the dynamic-response-based intact stability criterion is desirable for FOWTs to account for their unique dynamic responses and the impact of various operating conditions. This paper demonstrates the implementation of a FOWT intact stability assessment using the dynamic-response-based criterion. Performance-based criteria require observed behavior or quantifiable metrics as input for the method to be applied. This is demonstrated by defining the governing load cases for two conceptual FOWT semisubmersible designs at two sites. This work introduces benchmarks comparing the area-ratio-based and dynamic-response-based criteria, gaps with current methodologies, and frontier areas related to the wind overturning moment definition.

Vibrations of Foundations Interacting With Subsoil Experimental Studies and BE Calculations

1991 ◽  
Author(s):  
L. Gaul
Keyword(s):  
Boundary Element Method ◽  
Dynamic Response ◽  
Surface Waves ◽  
Boundary Element ◽  
Constitutive Equations ◽  
Experimental Studies ◽  
Boundary Elements ◽  
Experimental Techniques ◽  
Embedded Structures ◽  
Element Method

Abstract Calculation of the dynamic response of sensitive structures like foundations for vibrating machinery requires to take the interaction with subsoil into account. Structures and soil are discretized by boundary elements and coupled by a substructure technique. Viscoelastic constitutive equations contain fractional time derivatives. Surface waves generated by machine foundations and diffracted by embedded structures and soil inhomogeneities are analyzed by conventional and optoelectronic experimental techniques and calculated by the boundary element method (BEM).

scholarly journals Dynamic Response of Composite Steel Lining Structure under Blast Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Desen Kong ◽  
Yu Xu ◽  
Cheng Song
Keyword(s):  
Dynamic Response ◽  
Emergency Response ◽  
Steel Plate ◽  
Axial Stress ◽  
Subway Tunnel ◽  
Analysis Software ◽  
Research Results ◽  
Protection Method ◽  
Lining Structure ◽  
Composite Steel

According to the advantages of high tensile resistance and high shear strength of composite steel plate, a new antiexplosion protection method of composite steel plate lining structure is put forward. The numerical model of explosion impact of subway tunnel with composite steel plate lining structure was established by dynamic analysis software. The transient dynamic response of lining structure with the composite steel plate was simulated when explosion occurred. The research results show that the influence of explosive quantity on each point of composite steel plate lining structure is different and the change of acceleration near the centre of the detonation source is generally greater than the multiple of the increase of explosive quantity. The increase of velocity and displacement is basically consistent with the quantity of explosive. The influence of axial stress on the lining structure is the least, and the influence of the lining structure is greater in the y-direction than in the x-direction. The research results can provide the plan and basis for the emergency response of the subway tunnel.

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