scholarly journals Modeling Spring-In of L-Shaped Structural Profiles Pultruded at Different Pulling Speeds

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2748
Author(s):  
Alexander Vedernikov ◽  
Alexander Safonov ◽  
Fausto Tucci ◽  
Pierpaolo Carlone ◽  
Iskander Akhatov
Keyword(s):  
Numerical Model ◽  
Vinyl Ester ◽  
Mechanical Performance ◽  
Numerical Technique ◽  
Chemical Shrinkage ◽  
Software Suite ◽  
Subsequent Increase ◽  
Pultrusion Process ◽  
Linear Elastic ◽  
Insight Into

Cure-induced deformations are inevitable in pultruded composite profiles due to the peculiarities of the pultrusion process and usually require the use of costly shimming operations at the assembly stage for their compensation. Residual stresses formed at the production and assembly stages impair the mechanical performance of pultruded elements. A numerical technique that would allow the prediction and reduction of cure-induced deformations is essential for the optimization of the pultrusion process. This study is aimed at the development of a numerical model that is able to predict spring-in in pultruded L-shaped profiles. The model was developed in the ABAQUS software suite with user subroutines UMAT, FILM, USDFLD, HETVAL, and UEXPAN. The authors used the 2D approach to describe the thermochemical and mechanical behavior via the modified Cure Hardening Instantaneous Linear Elastic (CHILE) model. The developed model was validated in two experiments conducted with a 6-month interval using glass fiber/vinyl ester resin L-shaped profiles manufactured at pulling speeds of 200, 400, and 600 mm/min. Spring-in predictions obtained with the proposed numerical model fall within the experimental data range. The validated model has allowed authors to establish that the increase in spring-in values observed at higher pulling speeds can be attributed to a higher fraction of uncured material in the composite exiting the die block and the subsequent increase in chemical shrinkage that occurs under unconstrained conditions. This study is the first one to isolate and evaluate the contributions of thermal and chemical shrinkage into spring-in evolution in pultruded profiles. Based on this model, the authors demonstrate the possibility of achieving the same level of spring-in at increased pulling speeds from 200 to 900 mm/min, either by using a post-die cooling tool or by reducing the chemical shrinkage of the resin. The study provides insight into the factors significantly affecting the spring-in, and it analyzes the methods of spring-in reduction that can be used by scholars to minimize the spring-in in the pultrusion process.

Vortex-Induced Vibrations of a Rigid Cylinder on Non-Linear Elastic Supports

2006 ◽  
Author(s):  
S. Bourdier ◽  
J. R. Chaplin
Keyword(s):  
Circular Cylinder ◽  
Phase Flow ◽  
Linear Vibration ◽  
Chaotic Motions ◽  
Frequency Spectra ◽  
Elastic Supports ◽  
Linear Elastic ◽  
Vortex Induced Vibrations ◽  
Non Linear ◽  
Insight Into

The dynamics of vortex-induced vibrations of a rigid circular cylinder with structural non-linearities, introduced by means of discontinuities in the support system, are studied experimentally. The analysis of the measurements is carried out using non-linear vibration tools, i.e phase-flow portraits, frequency spectra, Lyapunov exponents and correlation dimensions, to provide an insight into the dynamical changes in the system brought about by restricting the motion. We show that chaotic motions can occur due to the structural non-linearities.

scholarly journals Structure and Identification of Solenin: A Novel Fibrous Protein from BivalveSolen grandisLigament

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Jun Meng ◽  
Gang-Sheng Zhang ◽  
Zeng-Qiong Huang
Keyword(s):  
Mechanical Performance ◽  
Type I ◽  
Fibrous Proteins ◽  
Repeat Sequences ◽  
Fibrous Protein ◽  
Secondary Structure Analysis ◽  
Solen Grandis ◽  
Opening And Closing ◽  
Insight Into

Fibrous proteins, which derived from natural sources, have been acting as templates for the production of new materials for decades, and most of them have been modified to improve mechanical performance. Insight into the structures of fibrous proteins is a key step for fabricating of bioinspired materials. Here, we revealed the microstructure of a novel fibrous protein: solenin fromSolen grandisligament and identified the protein by MALDI-TOF-TOF-MS and LC-MS-MS analyses. We found that the protein fiber has no hierarchical structure and is homologous to keratin type II cytoskeletal 1 and type I cytoskeletal 9-like, containing “SGGG,” “SYGSGGG,” “GS,” and “GSS” repeat sequences. Secondary structure analysis by FTIR shows that solenin is composed of 41.8%β-sheet, 16.2%β-turn, 26.5%α-helix, and 9.8% disordered structure. We believe that theβ-sheet structure and those repeat sequences which form “glycine loops” may give solenin excellence elastic and flexible properties to withstand tensile stress caused by repeating opening and closing of the shell valves in vivo. This paper contributes a novel fibrous protein for the protein materials world.

Optimizing Bottom Hole Assembly Design Criteria to Improve Mechanical Performance in Slim Hole Drilling Environment

2021 ◽  
Author(s):  
Stephen Fleming ◽  
Roberto Ucero ◽  
Yuliya Poltavchenko
Keyword(s):  
Mechanical Performance ◽  
State Of The Art ◽  
Hole Drilling ◽  
Force Analysis ◽  
Software Suite ◽  
Assembly Design ◽  
Positive Displacement ◽  
Drilling Performance ◽  
Bottom Hole ◽  
Bottom Hole Assembly

Abstract After analyzing the historical data of neighboring wells adjacent to the drilling site, 11 bit trips were required due to the low mechanical performance of the bottom hole assembly elements. This observation is based on maximum circulation hours and low helical bucking values that make it uneconomic to drill the sections with a positive displacement motor drive system. A redesign the bottom hole assembly was proposed to achieve an improved mechanical performance which allowed the section to be drilled with a single assembly. With a focus on increasing the mechanical limitations of the downhole elements, the use of 4 ¾" equipment is considered instead of the 3 ½" standard equipment used in this hole size. One of the biggest challenges was modifying the 4 ¾" positive displacement motor (PDM) to fit into the 5 ½" hole given that the mud motor has a maximum unmodified diameter of 5 ½". Using the force analysis module of a State-of-the-art BHA modelling software suite, multiple iterations were performed to simulate and validate an alternative PDM design and accompanying directional assembly. This new design featured modifications to an existing 4 ¾" PDM deploying a long gauge bit in combination with a fit for purpose measurement while drilling system. After numerous runs using this assembly design, it was found that there was no additional or unexpected wear of the modified Mud Motor components or associated elements of the downhole equipment. These observations act to validate the pre-job engineering force analysis. With the improved mechanical specifications of the 4 ¾" Bottom Hole Assembly (BHA) components, circulating hours were increased from 100 hours to 250+ hours in a stepwise process. This enabled drilling of the entire 5 ½" section with a single BHA, comparing favorably to the legacy approach with an average of eleven bit runs. The modified 4 ¾" PDM coupled with long gauge bit technology enabled a reduction in the oriented to rotate drilling ratio and an associated increase in the overall rate of penetration (ROP). It can be concluded that the substitution of 4 ¾" drilling equipment for 3 ½" in the 5 ½" hole section, increased the drilling efficiency between 30-50% according to field data obtained in Ukraine. The modified 4 ¾" PDM combined with long gauge bit technology has the potential to improve 5 ½" hole drilling performance in other locations. Following a structured planning process using State-of-the-art BHA modelling software suite enabling the evaluation of the significant forces that act in the drilling assembly and so significantly reducing the risks associated with exceeding the original design limits of the assembly. By improving the mechanical performance of the drilling assembly in a 5 ½" hole, new territory for drilling engineers and design engineers is now available to increase the drilling performance in slim wellbores.

A FEA Simulation Model for Thin-Walled C-Section Composite Beam Assembling With R-Angle Deviation

2014 ◽  
Author(s):  
Hua Wang ◽  
Suo Si
Keyword(s):  
Numerical Model ◽  
Composite Beam ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Element Model ◽  
Load Level ◽  
Compression Tests ◽  
Accurate Analysis ◽  
Angle Deviation ◽  
Thin Walled

There are unavoidable deviations, such as shrinkage and distortions, in the composite detail parts production due to the complexity of composites fabrication. Interests in the assembly analysis of composite beams have led to a need for more accurate analysis especially in the case of fabrication deviations. This work proposes a numerical finite element model of thin-walled C-section composite beam with R-angle deviation for assembling. The rule of Hashin failure combined with cohesive element is applied to study the mechanical performance of the fiber and matrix (implemented as user subroutine UMAT in ABAQUS) while positioning and clamping. Tension and compression tests are carried out based on available standards to determine the C-section beam behavior under load. The testing data validates the proposed numerical model. The numerical model captures the experimentally obtained results with minimal error, and predicts the failure modes successfully. The proposed model allows to determine accurately the first failure location and the associated load level. It will enhance the understanding of the composite components pre-loading analysis, and help systematically improving the composites assembling efficiency in civil aircraft industry.

Effect of the frictional coefficient and pre-tension on stress distribution of fabric during the weaving process

2017 ◽  
Vol 88 (8) ◽  
pp. 904-912
Author(s):  
Zhiping Ying ◽  
Zhenyu Wu ◽  
Xudong Hu ◽  
Xiangqing Zhou
Keyword(s):  
Numerical Model ◽  
Stress Distribution ◽  
Mechanical Performance ◽  
Frictional Coefficient ◽  
Woven Fabric ◽  
Weft Yarn ◽  
Tension Stress ◽  
Initial Shape ◽  
Warp Tension ◽  
Fluctuation Range

The non-uniform stress distribution of woven fabric has a significant influence not only on its mechanical performance in service, but also on its weaving efficiency in the fabrication process. For investigating the stress distribution in woven fabric, a numerical model at the yarn scale was established to simulate the interlacing process between the weft and warp yarns using an explicit finite element solver. The yarns were assumed to be a homogeneous continuum and the transversal isotropic constitutive equation was used. A modified lenticular initial shape was used as the cross-section of the yarn and trajectories of warp and weft yarns were set to be straight. The classical Amonton–Coulomb law was used for the tangential behavior between the weft and warp yarns. The simulation results reveal that the interaction between weft and warp yarns consists of three phases in terms of contact, adhesion and sliding. The sectional stress distribution in the weft yarn determined by multi-points contact between a single weft yarn and a group of warp yarns was also analyzed. The tension stress of the weft yarn was larger in the middle part than that in both sides. Based on the numerical model, the effects of two key parameters, namely the frictional coefficient and weft pre-tension, on the stress distribution were discussed in detail. The weft crimp angle and warp tension distribution uniformity decreased as the frictional coefficient decreased, whereas the warp tension fluctuation range did not obviously decrease. However, an improved method by exerting pre-tension in two ends of weft yarn was proposed and the warp tension fluctuation range was significantly decreased. The distribution trend of warp tension obtained from the numerical simulation showed an acceptable tendency with experiment measurements.

Shock Wave Structure in a Linear Elastic Mixture With Binary Chemical Reactions

1975 ◽  
Vol 42 (1) ◽  
pp. 171-175 ◽  
Author(s):  
J. W. Nunziato ◽  
E. K. Walsh ◽  
D. E. Amos
Keyword(s):  
Chemical Reactions ◽  
Numerical Technique ◽  
Wave Structure ◽  
Compressive Wave ◽  
Exothermic Reactions ◽  
Linear Elastic ◽  
Elastic Mixture ◽  
Solid Explosives ◽  
Thermochemical Equilibrium ◽  
And Diffusion

In this paper we consider the propagation of small-amplitude, one-dimensional shock waves in a linear elastic mixture with binary chemical reactions. The effects of heat conduction and diffusion are neglected. Using a numerical technique, along with the results of a singular surface analysis, the behavior of a compressive wave generated by a constant velocity suddenly applied to the boundary of a half space is determined. The influence of the type of chemical reaction and of the underlying state of thermochemical equilibrium on the wave behavior is discussed. In the case of exothermic reactions the results are found to be in qualitative agreement with some recent experimental observations on solid explosives.

Review of Analysis Model on Three-Dimensional Braided Composites

2014 ◽  
Vol 607 ◽  
pp. 881-885
Author(s):  
Hai Yan Chen ◽  
Gao Feng Wei ◽  
Yan Xu
Keyword(s):  
Numerical Model ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Single Step ◽  
Analysis Model ◽  
Micro Structure ◽  
Braided Composites ◽  
Reinforced Fiber

Because reinforced-fiber has characteristic of single step forming in three-dimensional braided composites, analysis of mechanical performance is very different from laminates. This paper proceeds from the micro-structure of 3-D braided composites, some review and research are presented detailedly, and the several model’s merit and demerit are analyzed, which can conduct dynamicists to choose reasonable numerical model. The mechanical performance can be predicted accurately, and the next research can be guided using above analysis.

Airflow-Housing-Induced Resonances of Rotating Optical Disks

2007 ◽  
Vol 74 (6) ◽  
pp. 1252-1263 ◽  
Author(s):  
R. M. C. Mestrom ◽  
R. H. B. Fey ◽  
H. Nijmeijer ◽  
P. M. R. Wortelboer ◽  
W. Aerts
Keyword(s):  
Numerical Model ◽  
Pressure Distribution ◽  
Critical Speed ◽  
Experimental Approach ◽  
Experimental Results ◽  
Lubrication Equation ◽  
Global View ◽  
Optical Disks ◽  
Insight Into ◽  
Finite Difference Techniques

Numerous excitation sources for disk vibrations are present in optical drives. For increasing rotation speeds, airflow-housing-induced vibrations have become more and more important. Currently, drives are designed in which rotation speeds are so high that critical speed resonances may show up. The presence of these resonances depends on the layout of the inner housing geometry of the drive. The influence of the drive inner housing geometry is investigated systematically by means of a numerical-experimental approach. An analytical model is derived, containing disk dynamics and the geometry-induced pressure distribution acting as the excitation mechanism on the disk. The Reynolds’ lubrication equation is used as a first approach for the modeling of the pressure distribution. The model is numerically implemented using an approach based on a combination of finite element and finite difference techniques. An idealized, drive-like environment serves as the experimental setup. This setup resembles the situation in the numerical model, in order to be able to verify the numerical model. Wedge-like airflow disturbances are used in order to obtain insight into the influence of drive inner geometry on the critical speed resonances of optical disks. A disk tilt measurement method is designed that yields a global view of the disk deformation. By means of two newly proposed types of plots, numerical and experimental results can be compared in a straightforward way. A qualitative match between the numerical and experimental results is obtained. The numerical and experimental methods presented provide insight into airflow-housing-induced vibrations in optical drives. Additionally, reduction of some critical speed resonances is found to be possible for certain drive inner geometry configurations.

Detailed Numerical and Experimental Investigation of Non-Isothermal Sintering of Amorphous Polymer Material

2002 ◽  
Vol 124 (3) ◽  
pp. 553-563 ◽  
Author(s):  
R. M. Tarafdar ◽  
T. L. Bergman
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Penetration Depth ◽  
Polymer Material ◽  
Amorphous Polymer ◽  
Experimental Results ◽  
Additional Insight ◽  
Morphological Response ◽  
Thermal Penetration Depth ◽  
Insight Into

Simulations and experiments are performed to investigate the coupled thermal and morphological response of polymer material during non-isothermal sintering. The experimental results are utilized to validate a numerical model that describes the response of the system. Predictions of the material expansion, its subsequent contraction due to sintering, and the temperature evolution are obtained and favorably compared with experimental results. Parametric simulations are performed to acquire additional insight into the dynamics of non-isothermal sintering while a relationship is established to describe the ratio of the sintering penetration depth to the thermal penetration depth and its dependence upon the boundary and initial temperatures.

Sign in / Sign up

Export Citation Format

Share Document