Structural dynamic loads in response to impulsive excitation

1995 ◽  
Vol 32 (4) ◽  
pp. 853-861 ◽  
Author(s):  
Mordechay Karpel ◽  
Eyal Presente
Keyword(s):  
Dynamic Loads ◽  
Structural Dynamic ◽  
Impulsive Excitation

Quench Polish Quench (QPQ) Coating Behavior Under Dynamic Loads

2017 ◽  
Author(s):  
Haifeng Zhao ◽  
Abraham Torres ◽  
Andrew Prisbell ◽  
Andrew Werner ◽  
Ahmed Abdelaal
Keyword(s):  
Oil And Gas ◽  
Peak Load ◽  
High Stress ◽  
Surface Hardness ◽  
Dynamic Loads ◽  
Engineering Practice ◽  
Mechanical Shock ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Physical Test

The selection of coating or surface treatments is a crucial step in the design of oil and gas equipment to protect against the deterioration caused by wear, corrosion, galling, fatigue, etc. Quench polish quench (QPQ) nitriding is a superior candidate to increase surface hardness for abrasion and galling resistance in carbon or stainless steels. The increased surface hardness improves the wear and corrosion resistance but reduces the surface material ductility. It is generally not recommended for application to V-shaped threads or sharp notches subjected to high stress. During well perforation in cased-hole completion, the detonation of the gun string along with the induced pressure wave in fluids generates a large-magnitude dynamic motion in the gun string. The peak load of a perforating event, from detonation to fluid-structure interaction, happens in the range of microseconds to milliseconds. The coupled wellbore hydrodynamic and structural dynamic shock load may cause an overstress failure in the millisecond scale but is usually overlooked in engineering practice. In this work, we investigated the behavior of QPQ coating under transient dynamic loads, employing both physical test and finite element analysis. We designed a combination of drop test fixture and specimens to simulate a notched specimen subjected to dynamic tensile loads. Two types of specimens were prepared in this study, QPQ-coated specimens and bare metal specimens without coating. The specimens without coating were tested to serve as a baseline for comparison. The methodology in this study provides a generic guideline for design of equipment potentially subjected to transient mechanical shock loads.

Dynamic Response of a Steel-Concrete Hybrid Frame to Support 15MW Compressor

2012 ◽  
Author(s):  
Seunghoon Shin ◽  
Guangyoung Sun ◽  
Juwon Lee ◽  
Kangboo Kim
Keyword(s):  
Dynamic Analysis ◽  
Structural Dynamics ◽  
Structural Design ◽  
Modal Testing ◽  
Dynamic Loads ◽  
Structural Vibration ◽  
Aerodynamic Load ◽  
Radial Load ◽  
Structural Dynamic ◽  
Test Result

In this paper, the structural dynamics study of the frame to support 15MW compressor is suggested. This study used the steel-concrete hybrid frame to support a large compressor system. This paper provided experimental and analytical method to structural design the hybrid frame by considering in rotordynamics and aerodynamics. Dynamic characteristics of the frame have to be identified to tune the finite element model’s boundary condition and to avoid resonance. Therefore modal testing of the frame is performed and boundary conditions are modified applying to the previously obtained modal parameters. While compressor is operated, multiple dynamic loads of compressor, motor and expander may excite on the frame. The total dynamic load is derived by axial aerodynamic load of impeller, radial load of gear and unbalance load of rotor. After dynamic analysis completion, the analysis result is compared with test result to verify the accuracy of analysis. Through this structural dynamic analysis, structural vibration response of hybrid frame can be estimated.

scholarly journals Identification of Dynamic Loads Based on Second-Order Taylor-Series Expansion Method

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaowang Li ◽  
Zhongmin Deng
Keyword(s):  
Series Expansion ◽  
Taylor Series ◽  
Time History ◽  
Taylor Series Expansion ◽  
Second Order ◽  
New Method ◽  
Dynamic Loads ◽  
Discrete Equation ◽  
System Response ◽  
Structural Dynamic

A new method based on the second-order Taylor-series expansion is presented to identify the structural dynamic loads in the time domain. This algorithm expresses the response vectors as Taylor-series approximation and then a series of formulas are deduced. As a result, an explicit discrete equation which associates system response, system characteristic, and input excitation together is set up. In a multi-input-multi-output (MIMO) numerical simulation study, sinusoidal excitation and white noise excitation are applied on a cantilever beam, respectively, to illustrate the effectiveness of this algorithm. One also makes a comparison between the new method and conventional state space method. The results show that the proposed method can obtain a more accurate identified force time history whether the responses are polluted by noise or not.

scholarly journals In-Situ Dynamic Response Measurement for Damage Quantification of 3D Printed ABS Cantilever Beam under Thermomechanical Load

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2079 ◽  
Author(s):  
Hamzah Baqasah ◽  
Feiyang He ◽  
Behzad A. Zai ◽  
Muhammad Asif ◽  
Kamran A. Khan ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Crack Propagation ◽  
Crack Depth ◽  
Dynamic Loads ◽  
Laser Vibrometer ◽  
Response Measurement ◽  
Structural Dynamic ◽  
Fused Deposition ◽  
And Behavior

Acrylonitrile butadiene styrene (ABS) offers good mechanical properties and is effective in use to make polymeric structures for industrial applications. It is one of the most common raw material used for printing structures with fused deposition modeling (FDM). However, most of its properties and behavior are known under quasi-static loading conditions. These are suitable to design ABS structures for applications that are operated under static or dead loads. Still, comprehensive research is required to determine the properties and behavior of ABS structures under dynamic loads, especially in the presence of temperature more than the ambient. The presented research was an effort mainly to provide any evidence about the structural behavior and damage resistance of ABS material if operated under dynamic load conditions coupled with relatively high-temperature values. A non-prismatic fixed-free cantilever ABS beam was used in this study. The beam specimens were manufactured with a 3D printer based on FDM. A total of 190 specimens were tested with a combination of different temperatures, initial seeded damage or crack, and crack location values. The structural dynamic response, crack propagation, crack depth quantification, and their changes due to applied temperature were investigated by using analytical, numerical, and experimental approaches. In experiments, a combination of the modal exciter and heat mats was used to apply the dynamic loads on the beam structure with different temperature values. The response measurement and crack propagation behavior were monitored with the instrumentation, including a 200× microscope, accelerometer, and a laser vibrometer. The obtained findings could be used as an in-situ damage assessment tool to predict crack depth in an ABS beam as a function of dynamic response and applied temperature.

scholarly journals Real-Time Identification of Dynamic Loads Using Inverse Solution and Kalman Filter

2020 ◽  
Vol 10 (19) ◽  
pp. 6767
Author(s):  
Jinhui Jiang ◽  
Shuyi Luo ◽  
M. Shadi Mohamed ◽  
Zhongzai Liang
Keyword(s):  
Kalman Filter ◽  
Real Time ◽  
Earthquake Engineering ◽  
State Vector ◽  
The State ◽  
Dynamic Loads ◽  
Unbiased Estimation ◽  
System Response ◽  
Structural Dynamic ◽  
Online Identification

Evaluating dynamic loads in real time is crucial for health monitoring, fault diagnosis and fatigue analysis in aerospace, automotive and earthquake engineering among other vibration related applications. Developing such algorithms can be vital for several safety and performance functionalities. Therefore, over the past few years the identification of dynamic loads has attracted a lot of attention; however, little literature on the online identification can be found. In this paper, we propose an online-identification method of structural dynamic loads so that the dynamic load is evaluated in real time and while the system response is still being measured. This is achieved by significantly improving the identification efficiency while retaining a high accuracy. The proposed method which is based on Kalman filter, is introduced in detail for a finite as well as an infinite number of degrees of freedom. Starting from an initial guess of the state vector we evaluate the error covariance, which then helps to identify the value of the excitation force using a weighted least square method and minimizing the covariance unbiased estimation. This is repeated at certain time intervals i.e., time steps where the state vector is updated in real time as acceleration measurements are updated. The feasibility of the method is validated using numerical simulations and an experimental verification where a detailed LabVIEW (National Instruments Ltd.) implementation is provided.

Prediction of random dynamic loads using second-order blind source identification algorithm

2020 ◽  
Vol 234 (9) ◽  
pp. 1720-1732
Author(s):  
You Jia ◽  
Zhichun Yang ◽  
Erqiang Liu ◽  
Yanhong Fan ◽  
Xuexia Yang
Keyword(s):  
Frequency Response ◽  
Frequency Domain ◽  
Source Identification ◽  
Second Order ◽  
Dynamic Loads ◽  
Modal Parameters ◽  
Frequency Domain Method ◽  
Identification Algorithm ◽  
Structural Dynamic ◽  
Comparison Results

Traditional load identification methods are based on the frequency response function matrix. However, in some cases, it is impossible to measure the frequency response functions directly, where only the measured structural dynamic response data are available. In this paper, a novel frequency domain method based on second-order blind source identification (SOBI) algorithm is proposed for identifying the random dynamic loads from some dynamic responses of limited test points. Firstly, the SOBI algorithm is applied to identify the modal parameters from the time histories of the measured displacement responses and then the modal loads are estimated by the identified modal parameters and modal responses in the modal space; finally, the random dynamic loads can be identified in the frequency domain. In order to control the error propagation, the theoretical formulas of the regularization process have been deduced, and the regularization parameters are selected by the generalized cross-validation method. A numerical simulation and an eight-storey spatial frame experimental model are studied to validate the proposed method; the comparison results show a good agreement between the identified random dynamic loads and the actually exerted loads.

Structural dynamic response analysis due to the slit flow between the tailplane and the elevator

2021 ◽  
pp. 095441002110169
Author(s):  
Ju Qiu ◽  
Jiali Tang ◽  
Chundu Sun ◽  
Fengyu Dai
Keyword(s):  
Flow Field ◽  
Vibration Analysis ◽  
Vibrational Frequency ◽  
Dynamic Loads ◽  
Structural Vibration ◽  
Response Analysis ◽  
Vibrational Motion ◽  
Structural Failure ◽  
Structural Dynamic ◽  
Slit Flow

Any aircraft in flight is subjected to dynamic loads. Following vibration-related accidents, a flow field and vibration analysis can be carried out to analyze the data and study the cause of the accident. When slit airflow enters the cavity between the tailplane structure and the elevator, a mixed vortex is formed. If the vortex-induced vibrational frequency of around 50 Hz happens to be close to the natural frequency of the structure at 46 Hz, it is likely to induce structural vibration (resonance). The resonance can cause excessive fatigue damage which can ultimately lead to structural failure and the loss of the component or the aircraft. Damping methods can be employed to control vibration within the structure by reducing the amplitude of that vibrational motion by 83%. This article details a recreation of one example of structural vibration within an airborne aircraft.

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