scholarly journals Is the Viscoelastic Sheet for Slamming Impact Ready to Be Used on Glass Fiber Reinforced Plastic Planning Hull?

2020 ◽  
Vol 10 (18) ◽  
pp. 6557 ◽  
Author(s):  
Patrick Townsend ◽  
Juan Carlos Suárez Bermejo ◽  
Paz Pinilla ◽  
Nadia Muñoz
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Damage Threshold ◽  
Fluorescent Light ◽  
Glass Fiber Reinforced Plastic ◽  
Additional Layer ◽  
Glass Fiber Reinforced ◽  
Weight Drop ◽  
Viscoelastic Layers ◽  
The Impact

Planing hull vessel built with polymer matrix laminates and fiberglass reinforcements (GFRP) suffer structural damage due to the phenomenon of slamming during navigation, due to the impact of the boat hull on the free surface of the water at high speed. A modification in the manufacture of the laminates for these fast boats is proposed, consisting of the insertion of an additional layer of a hybrid material, formed by elastomer encapsulated in an ABS polymer cell. Using GFRP specimens made from pre-impregnated material and reproducing the characteristic impacts of slamming, it is possible to compare the modified material with the introduction of the viscoelastic layers with the response under the same conditions as the unmodified laminates. Additionally, the panels have been tested using impacts due to weight drop at different energies, which allow determining the material damage threshold as a function of the energy absorbed, and to establish a comparison with the GFRP panels modified by observation in fluorescent light. It is verified that the proposal to reduce the effect of these impacts on the generation of damage to the material and its progression throughout the service life of the vessel is effective.

scholarly journals Effect of Temperature and Water Absorption on Low-Velocity Impact Damage of Composites with Multi-Layer Structured Flax Fiber

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 453 ◽  
Author(s):  
Yiou Shen ◽  
Junjie Zhong ◽  
Shenming Cai ◽  
Hao Ma ◽  
Zehua Qu ◽  
...  
Keyword(s):  
Water Absorption ◽  
Structural Damage ◽  
Impact Damage ◽  
Damage Threshold ◽  
Flax Fiber ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Damage Resistance ◽  
The Impact

Temperature and moisture can cause degradation to the impact properties of plant fiber-based composites owing to their complex chemical composition and multi-layer microstructure. This study focused on experimental characterization of the effect of important influencing factors, including manufacturing process temperature, exposure temperature, and water absorption, on the impact damage threshold and damage mechanisms of flax fiber reinforced composites. Firstly, serious reduction on the impact damage threshold and damage resistance was observed, this indicated excessive temperature can cause chemical decomposition and structural damage to flax fiber. It was also shown that a moderate high temperature resulted in lower impact damage threshold. Moreover, a small amount of water absorption could slightly improve the damage threshold load and the damage resistance. However, more water uptake caused severe degradation on the composite interface and structural damage of flax fiber, which reduced the impact performance of flax fiber reinforced composites.

Impact Pressures on the Bottom of a Prismatic Planing Hull During Water Impact

2015 ◽  
Author(s):  
Carolyn Q. Judge ◽  
John A. Judge ◽  
Christine M. Ikeda
Keyword(s):  
Pressure Distribution ◽  
Structural Design ◽  
Structural Damage ◽  
High Speed ◽  
Empirical Method ◽  
Naval Academy ◽  
Water Impact ◽  
Empirical Estimates ◽  
Peak Pressures ◽  
The Impact

High-speed planing boats are subject to repeated slamming impacts, which can cause structural damage and discomfort or injury to passengers. The structural and seakeeping aspects of the design of high-speed craft are mainly determined through empirical estimates of mean and peak pressures. The primary structural guideline (Allen and Jones, 1978) relies heavily on semi-empirical criteria that are not always accurate and have limited application. The Allen and Jones guidelines provide conservative estimates leading to sufficient structural design, but do not provide enough guidance to allow strategic reduction in structural weight. Structural design depends on the hull bottom pressures while information about the magnitudes of peak pressures, time durations, and locations along the hull is generally not available. Model tests conducted at the US Naval Academy have measured bottom pressures on a prismatic planing hull geometry during operation in waves (both regular and irregular). Pressures were measured at point locations and using a two-dimensional pressure pad to examine how pressures change in both time and space during a water impact. Rosen (2005) presents a method for reconstructing the momentary pressure distribution during a hull-water impact. This method allows the measurements of a propagating pressure segment in one position of the hull at one instant in time to be associated with other positions at other instants in time (as determined from several different point pressure measurements). Morabito (2014) presents an empirical method for calculating the pressure distribution on the bottom of prismatic planing hulls. The method can be extended to the impact problem by use of an “equivalent” planing velocity. This paper compares the planing pressures predicted by Morabito's empirical method with the recreated pressure distribution determined from Rosen's method.

Safety evaluation of buildings under flood impact

2021 ◽  
Author(s):  
Youtong Rong ◽  
Paul Bates ◽  
Jeffrey Neal
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Flow Direction ◽  
Interaction Model ◽  
Dam Break ◽  
Maximum Pressure ◽  
Two Phase ◽  
Maximum Deformation ◽  
Flood Impact ◽  
The Impact

<p>The flood caused by a dam-break event generally contains a large amount of energy, and it can be destructive to the downstream buildings and structures. An experiment-validated three-dimensional numerical model was designed to investigate the impact of dam-break flood on structures with different arrangements. The Eulerian two-phase flow model and the smooth particle dynamics method are applied separately to solve the flow motion, and  the deformation characteristics of buildings under the flood impact are evaluated by fluid-structure interaction model. An experiment is constructed to validate the numerical simulation. The results show that the structure suffers a large instantaneous impact pressure when the flood water first contacts the structure, and the value of this pressure can reach 1.5-3.0 times that of the maximum pressure after the first impact, and the maximum total pressure of the upstream building surface is about 1800N. The deformation near the door and windows is obvious, and the maximum deformation can reach 600μm, which further results in the large deformation of the gable and roof on both sides. Moreover, the arrangement of buildings has different blocking effect on flood. The back-row buildings arranged in alignment along the flow direction still has to bear 20% flood impact, and the front row buildings arranged alternately bear 90% high-speed flow impact. The structural damage is evaluated by the material failure criterion, and the weak position of buildings is identified, providing an optimal design of buildings.</p>

Experimental investigations on the drilling parameters to minimize delamination and taperness of hybrid GFRP/Al2O3 composites by using ANOVA approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gadhamsetty Guru Mahesh ◽  
Jayakrishna Kandasamy
Keyword(s):  
Optimum Condition ◽  
Process Parameters ◽  
Signal To Noise Ratio ◽  
Experimental Investigations ◽  
Content Type ◽  
Glass Fiber Reinforced Plastic ◽  
Glass Fiber Reinforced ◽  
Drilling Parameters ◽  
Drill Diameter ◽  
The Impact

Purpose Drilling holes in composite materials is a complex and challenging process because of their intrinsic anisotropic characteristics and unevenness compared to conventional metals. Hybridization of composites enhances the strength and hardness of the material but makes it more difficult to drill a hole in it. The purpose of this study is to optimize the drilling to minimize the delamination and taperness of hybrid glass fiber reinforced plastic (GFRP)/Al2O3 composites. Design/methodology/approach The present study investigates the impact of drilling parameters on delamination of the drilled hole and the taperness of the hole on hybrid GFRP/Al2O3. Optimum drilling conditions for minimizing delamination and taperness of the hole are determined to enhance the hole quality. Feed (f), speed (N) and drill diameter (D) are the parameters taken into consideration for drilling operation. By applying Taguchi’s signal-to-noise ratio analysis, process parameters have been optimized to reduce the delamination and taperness of holes on Hybrid GFRP/Al2O3 composites. The effect of process parameters was analyzed using the analysis of variance method. Findings The investigational results confirmed that the delamination is positively affected by speed, drill diameter and feed rate. Also, the taperness of the hole is positively affected by the drill diameter. Regression-based models were developed to predict the delamination and taperness of the hole matched with the experimental results, which are attained with an order of 95% and 97%. Originality/value Minimum delamination was found at the optimum condition of drill diameter 10 mm, feed at 0.225 mm/rev and the speed at 151 rpm and minimum taperness were found at the optimum condition of drill diameter 10 mm, feed at level 0.3 mm/rev and speed at 86 rpm for hybrid laminate composite (S-glass+ GFRP/Al2O3) were evaluated.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Sign in / Sign up

Export Citation Format

Share Document