scholarly journals Computer Aided Internal Optimisation (CAIO) method for fibre trajectory optimisation: A deep dive to enhance applicability

2020 ◽  
Vol 6 ◽  
Author(s):  
Harald Voelkl ◽  
Michael Franz ◽  
Daniel Klein ◽  
Sandro Wartzack
Keyword(s):  
Normal Stress ◽  
Lightweight Design ◽  
Single Layer ◽  
Shear Stresses ◽  
Convergence Criteria ◽  
Deep Dive ◽  
Reinforced Plastics ◽  
Computer Aided ◽  
Laminate Design ◽  
Distinguished Contribution

The computer aided internal optimisation (CAIO) method produces an optimised fibre layout for parts made from fibre-reinforced plastics (FRP), starting from an initial shell geometry and a given load case. Its main principle is iterative reduction of shear stresses by aligning fibre main axes with principal normal stress trajectories. Previous contributions, ranging from CAIO’s introduction over testing to extensions towards multi-layer FRP laminates, highlighted its lightweight design potential. For its application to laminate design approaches, alterations have been proposed; however, questions remain open. These questions include which convergence criteria to use, how to handle ambiguous principle normal stress trajectories, influence of using multi-layer CAIO optimisation instead of the initial single-layer CAIO and how dire consequences of slightly deviating fibre orientations from the optimised trajectories are. These challenges are discussed in depth and guidelines are given. This paper is an enhanced version of a distinguished contribution at the first symposium ‘Lightweight Design in Product Development’, Zurich (June 14–15, 2018).

An Optimization Method for Optimal Engineering Structure Design Combining Intelligent Optimization Algorithm and CAE Code

2011 ◽  
Vol 399-401 ◽  
pp. 2296-2300
Author(s):  
Wen Jie Peng ◽  
Rui Ge ◽  
Ming Kai Gu
Keyword(s):  
Analytical Solution ◽  
Normal Stress ◽  
Optimization Algorithm ◽  
Optimization Method ◽  
Structure Design ◽  
Stacking Sequence ◽  
Intelligent Optimization ◽  
Engineering Structure ◽  
Intelligent Optimization Algorithm ◽  
Computer Aided

This paper presents an optimization method for optimal engineering structure design. An interface procedure is essentially developed to combine the intelligent optimization algorithm and computer aided engineering (CAE) code. An optimization example is carried out to minimize the interlaminar normal stress of a laminate which affect the delamination failure of a laminate via arranging the stacking sequence. The analytical solution is calculated to validate the accuracy of optimization results.

scholarly journals Performance analysis of the bump beams made of High Strength Steel and Carbon Fiber reinforce plastics

2018 ◽  
Vol 207 ◽  
pp. 03006
Author(s):  
Yi Yao ◽  
Quan Yuan ◽  
Sihuan Fu
Keyword(s):  
Carbon Fiber ◽  
Automobile Industry ◽  
High Strength Steel ◽  
Lightweight Design ◽  
High Strength ◽  
Research Directions ◽  
Deformation And Failure ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics ◽  
Fiber Reinforce

Lightweight and safe are the key research directions of the automobile industry. Bump beam is an important part of the car safety protection and it’s lightweight design has drawn much attention. In this paper, the static strength and the low-speed impact performances of two types of bump beam with the same structure, which made of carbon fiber reinforced plastics (CFRP) and high strength steel (HSS), were investigated. Under the condition of static press, frontal and 40% offset impact, part structural stiffness, component crush intrusion, energy absorption were comparison analyzed. In order to guide the product design, the deformation and failure of CFRP beams with five different laminate structures were simulated under frontal and 40% offset impact. The results indicate that, with the same structure, the properties of CFRP bump beam are generally superior to HSS product, more conducive to lightweight and the optimum design of the laminate is [0° / 60° / 120°]

Sandwich Structures for Naval Ships: Design and Experience

2000 ◽  
Author(s):  
Karl-Axel Olsson
Keyword(s):  
Lightweight Design ◽  
Weight Ratio ◽  
Point Of View ◽  
Economic Point ◽  
Plastic Foams ◽  
Reinforced Plastics ◽  
Sandwich Construction ◽  
Glass Fibre Reinforced Plastic ◽  
Glass Fibre Reinforced ◽  
Common Face

Abstract In Sweden we have a long experience with different types of vehicles and ships in sandwich construction, especially Navy ships such as minesweepers, mine-counter-measure-vessels and corvettes. GRP (Glass fibre Reinforced Plastic) and FRP (Fibre Reinforced Plastics) have been the most common face materials, but metallic materials such as Al-alloys, coated carbon steel and stainless steel have also been used. Core materials have usually been cellular plastic foams of cross-linked PVC (Polyvinyl-chloride), but also extruded PS (Poly-styrene), PUR (Poly-urethane), PEI (Poly-ether-imide) and PMI (Poly-methacryl-imide). Different continuous and discontinuous manufacturing processes have been used. Vacuum assisted infusion has been introduced recently, because it is a closed process, gives high fibre content and a good quality of the laminates. Sandwich design has mainly been used in the transportation area, where lightweight design is needed to give higher performance and load bearing capacity. The use of sandwich construction will give high stiffness- and strength-to weight ratio. This is usually not enough from an economic point of view to justify the introduction of sandwich construction, but other integrated functions must be considered, i.e. insulation, energy consumption, damping, fewer components, lower manufacturing costs, low maintenance, signature effects (military) etc.

Optimization of Orthotropic Laminates

1967 ◽  
Vol 89 (3) ◽  
pp. 399-402 ◽  
Author(s):  
L. Fischer
Keyword(s):  
Stress Distribution ◽  
Structural Design ◽  
Single Layer ◽  
Design Criteria ◽  
Shear Stresses ◽  
Stress Strain ◽  
Mathematical Procedure ◽  
Optimum Structural Design ◽  
Interaction Equation

Stress-strain relationships for a single layer are used to obtain the stress distribution in a laminate composed of any number of orthotropic layers subjected to axial and shear stresses. The mathematical procedure is simplified for an isotropic laminate. An interaction equation is presented to predict failure of a laminate. Optimum structural design criteria are obtained by considering different combinations of layer orientations.

Evolution of Slip Through the Thickness of a Single-Crystal Nickel-Base Superalloy Notched Specimen

2006 ◽  
Author(s):  
Shadab Siddiqui ◽  
Nagaraj K. Arakere ◽  
Fereshteh Ebrahimi
Keyword(s):  
Stress Concentration ◽  
Single Crystal ◽  
Normal Stress ◽  
Elastic Anisotropy ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Specimen Thickness ◽  
Face Centered Cubic ◽  
Slip Systems ◽  
Base Superalloy

Deformation mechanisms and failure modes of FCC (face centered cubic) single crystal components subjected to triaxial states of static and fatigue stress are very complicated to predict, because plasticity precedes fracture in regions of stress concentration, and the evolution of plasticity on the surface and through the thickness is influenced by elastic and plastic anisotropy. The triaxial stress state at regions of stress concentration results in the activation of many slip systems that otherwise would not be activated during uniaxial testing. We recently presented [1] results from a numerical and experimental investigation of evolution of slip systems at the surface of notched FCC single crystal specimens, as a function of secondary crystallographic orientation. Results showed that the slip sector boundaries have complex curved shapes with several slip systems active simultaneously near the notch. We extend our work on slip at the surface to investigating the evolution of slip or plastic deformation through the thickness of the specimen. A single crystal double-edge-notched rectangular specimen of a Ni-base superalloy, under the tensile loading ([001] load orientation and [110] notch direction) is considered. A three dimensional (3-D) finite element model (FEM) including elastic anisotropy is used for the numerical investigation. Results indicate that the stress distribution and slip fields are a strong function of axial location through the thickness. Numerical results are verified by comparing them with experimentally observed slip fields. We demonstrate that inclusion of three dimensional analysis and elastic anisotropy is important for predicting evolution of slip at the surface and through the specimen thickness. The resolved shear stresses (RSS) on the dominant slip systems and the normal stress on the dominant planes are shown to vary significantly from the surface to the midplane of the specimen. Based on the consideration of RSS, normal stress and the number of activated slip systems at each thickness level, it is concluded that fatigue cracks most likely start in the midplane, for the orientation reported here.

Mechanical and optical properties of silk fabric/glass fiber mat composites: an artistic application of composites

2017 ◽  
Vol 88 (8) ◽  
pp. 932-945 ◽  
Author(s):  
Yuqiu Yang ◽  
Defang Zhao ◽  
Jing Xu ◽  
Yuying Dong ◽  
Yan Ma ◽  
...  
Keyword(s):  
Optical Properties ◽  
Glass Fiber ◽  
Light Transmission ◽  
Single Layer ◽  
Negative Influence ◽  
Silk Fabric ◽  
Glass Composites ◽  
Reinforced Plastics ◽  
Glass Fiber Reinforced ◽  
The Impact

Currently, hybrid glass fiber-reinforced plastics (GFRPs) have attracted increasing attention as gradually common used materials. Glass/silk fiber hybrid reinforced plastic (GSFRP), a new kind of material, is designed aiming to create a kind of opaque effect of specific use. Three types of silk/glass composites with five layers of glass mats and a single layer of woven silk fabric lamina with small, medium and large crepe are fabricated by using the hand lay-up method to compare with pure GFRP. Optical properties, including the light transmission property and luminance distribution, were examined with regard to the specimens of GSFRP. Results indicate that light was diffused more efficiently by GSFRP than pure GFRP laminates. Moreover, the greater the crepe degree of silk fabric is, the more efficiently light is diffused and the rise of luminance suppressed. Furthermore, mechanical properties, including the flexural as well as the impact property, were examined through three-point bending and Izod tests, respectively. There is little negative influence on the flexural strength of GSFRP when silk inserted in layer 3 and, as the crepe degree of silk fabric increases, a slightly inferior effect on the impact test presented. From the scanning electron microscopy observation, it is found that the existence of silk fabric inserted in layer 3 could prevent further propagation of the crack and alleviate the delamination of the specimens during the bending process, improving resistance to delamination and bending.

scholarly journals Empirical Studies of Ice Sliding

1979 ◽  
Vol 23 (89) ◽  
pp. 157-170 ◽  
Author(s):  
W. F. Budd ◽  
P. L. Keage ◽  
N. A. Blundy
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Sliding Friction ◽  
Normal Load ◽  
Water Pressure ◽  
Empirical Studies ◽  
Shear Stresses ◽  
Friction Characteristic ◽  
Wide Range ◽  
Static Shear

AbstractAn experimental programme has been carried out for studying temperate-ice sliding over rock surfaces with a wide range of roughnesses, for normal and shear stresses comparable to those expected under real ice masses. The limiting static shear stress for acceleration has been found to be directly proportional to the normal load giving a constant limiting coefficient of static friction characteristic of the surface. For a constant applied normal stress N and shear stress τb, well below the limiting static shear, a steady velocity Vb results which increases approximately proportionally to τb and decreases with increasing N and the roughness of the surface. For high normal stress the velocity becomes approximately proportional to the shear stress cubed and inversely proportional to the normal stress. As the shear stress increases acceleration sets in, which, for different roughness and normal loads, tends to occur for a constant value of the product τbVb. For some surfaces at high normal loads this acceleration was retarded by erosion. For constant-applied-velocity tests a steady shear stress resulted, which tended to become constant with high velocities, and which increased with increasing normal stress but with a reduced coefficient of sliding friction. The relevance of the results to the sliding of real ice masses is discussed with particular reference to the importance of the effect of the relative normal stress, above basal water pressure, to the sliding rate.

VISCOUS CONTRIBUTIONS TO THE PRESSURE FOR THE POTENTIAL FLOW ANALYSIS OF MAGNETOHYDRODYNAMIC KELVIN–HELMHOLTZ INSTABILITY

2012 ◽  
Vol 04 (01) ◽  
pp. 1250001 ◽  
Author(s):  
MUKESH KUMAR AWASTHI ◽  
G. S. AGRAWAL
Keyword(s):  
Normal Stress ◽  
Potential Flow ◽  
Mechanical Energy ◽  
Flow Analysis ◽  
Shear Stresses ◽  
Helmholtz Instability ◽  
Viscous Potential Flow ◽  
Two Fluids ◽  
Tangential Stresses ◽  
Viscous Pressure

The present paper deals with the study of viscous contributions to the pressure for the viscous potential flow analysis of Kelvin–Helmholtz instability with tangential magnetic field at the interface of two viscous fluids. Viscosity enters through normal stress balance in the viscous potential flow theory and tangential stresses for two fluids are not continuous at the interface. Here, we have considered viscous pressure in the normal stress balance along with the irrotational pressure and it is assumed that the addition of this viscous pressure will resolve the discontinuity between the tangential stresses and the tangential velocities at the interface. The viscous pressure is derived by mechanical energy equation and this pressure correction applied to compute the growth rate of magnetohydrodynamic Kelvin–Helmholtz instability. A dispersion relation is obtained and stability criterion is given in the terms of critical value of relative velocity. It has been observed that the inclusion of irrotational shear stresses have stabilizing effect on the stability of the system.

Numerical Study of Cruciform Specimens for Biaxial Tensile Tests

2016 ◽  
Author(s):  
Luis F. Puente Medellín ◽  
Antonio Balvantin ◽  
J. A. Diosdado-De la Peña
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Normal Stress ◽  
Sheet Metal ◽  
Numerical Study ◽  
Tensile Tests ◽  
Thickness Reduction ◽  
Shear Stresses ◽  
Normal Stress Distribution ◽  
Biaxial Tensile

This paper presents a numerical study of different geometries of cruciform specimens for biaxial tensile tests. The aim of these specimens is to be used on fixtures for biaxial tests mounted in universal testing machines. For the study, a model of isotropic material for steel sheet metal specimens was considered. Thus, only the mechanical properties of the sheet metal in the rolling direction were considered in the simulations. In this numerical analysis, the normal stress distribution and the consequent shear stress were studied. Additionally, the effect of the inclusion of multiple slots as well as a thickness reduction on the normal and shear stresses were assessed. Hence, a specimen in which a uniform normal stress distribution with zero shear stress, is necessary. The results of the analysis show that a specimen with features, multiple slots and a thickness reduction in the central area, provides a better performance in the simulations than dismissing any of these characteristics. Finally, a specimen model suitable for the mentioned test is proposed according to the obtained numerical results and the feasibility of manufacture of the experimental sample-test.

Mechanical Behavior of Loops with Small Diameters

2017 ◽  
Vol 742 ◽  
pp. 374-380
Author(s):  
Anna Lang ◽  
Oliver Focke ◽  
Axel S. Herrmann
Keyword(s):  
Mechanical Behavior ◽  
Design Method ◽  
Lightweight Design ◽  
Rotor Blades ◽  
Test Method ◽  
Failure Behavior ◽  
Reinforced Plastics ◽  
Reinforced Plastic ◽  
Testing Data ◽  
Non Destructive

To meet the comprehensive requirements of lightweight design, a material minded design method will be aimed. A fiber minded solution for load application in fiber reinforced plastics are loop joints, which are mainly applied for introducing high concentrated tensile loads, e.g. in mountings for rotor blades, or in pre-tensioned supporting structures. Usually, these loop joints consist of, diameters in centimeter scale. Miniaturized loop joints with diameters in millimeter scale are applied in transition structures for carbon reinforced plastic-aluminum multi material designs. Factors of miniaturization influencing the mechanical behavior are decoupled for tensile testing. Data from computer tomography provides information on the failure behavior of loop joints. To validate the non-destructive test method microsections will be used.

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