composite structure design - khai · 2018-08-27 · optimal design of composite structures y...

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03

Email: [email protected]

Website: http://k403.khai.edu

National Aerospace University “KhAI” Department of Composite Structures and Aviation Materials

Based on the analytical methodology for determination of optimal structure of composite material

we have developed, validated and implemented in the software general algorithms for automated

design of common composite components like roads, bars, beams, shells, panels, etc.

Among them are:

Tailored Software for Composite Components Design

Thanks to 50+ years of experience in aerospace structures design, the Department researchers

are very strong in development of analytical models and optimization algorithms for composite

structures design for aerospace, automotive, marine, energy, sport & leisure and other applications.

To develop efficient structure that meet complex requirements we usually begin with determination

of optimal structure of composite material (ply numbers, orientation, staking sequence, etc.) for the

whole structure or its components on the basis of:

Optimal Design of Composite Structures

y Software for design of composite panel of minimal weight, which provides a broad range of

design options to the customer, including selection of preferable ply orientation(s), reinforcement

scheme complexity, failure mode(s), failure criterion, etc.

y Software for composite-to-metal joints design, which could be used for design and validation of

both conventional adhesive joints and innovative hybrid joints with micro-fasteners

y Software for design and checking calculation of full-composite low aspect wing, which realises

simplified analytical design and detailed FEM analysis with consideration for real geometry and

loading conditions

Intelligent approach to composite structures design is essential to meet complex requirements and

provide the best solution to the customer

What we do: y Develop and validate radically new design solutions for complex and integral composite structures

y Develop analytical models for composite structures design and optimization

y Implement analytically-based algorithms for design of typical composite components in customized software

y Structure loading conditions (including multiple loading cases) and safety factors

y Required structure rigidity and stability

y Mechanical properties and allowables of composite lamina(s)

We solve this problem for laminated and 3D reinforced composites as well as braided composite

preforms.

To validate analytical-based design we use finite element analysis and full-scale tests.

Composite Structure DesignReliable design procedures and innovative approaches

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Innovative Solutions in Composite Structures Design

The focal point of the Department R&D activities is development and validation of radically new

design solutions for complex and integral composite structures. Among our latest achievements in

this area are:

Numerous benefits of integral structures make effective integration of composites and metal a new

focal point of composites research

Hybrid Joints for Heavy-Loaded Composite-to-Metal Structures

The Department has developed and successfully applied a novel type of joints for heavy-loaded

composite-to-metal structures. Hybrid joints design is based on the principles of mechanical

fasteners miniaturization and metal joining fitting integration to composite structure before the final

curing.

High load-carrying capacity of hybrid joints (up to 70…95% of UD-carbon plastic strength) and

possibility of their application for joining of rods, wing spars, panels, and other structures are proved

experimentally.

We have created efficient structural and manufacturing solutions of hybrid joints for different

applications as well as tailored fasteners (bolts, nuts, washers, brackets, knees, fittings, etc.) with

longitudinal and transversal micro-fasteners.

To support hybrid joints design we have developed advanced model for precise calculation of

physical and mechanical characteristics of fibre-reinforced composites with embedded micro-

fastener(s) taking into account local effects.

Composite Structure DesignReliable design procedures and innovative approaches

What we offer: y Innovative design solutions for your specific needs

y Reliable design and multi-parametric optimization of composite structures of any complexity

y Advanced courses on composite structures design

y Full-composite aircraft fuselage section based on lattice stiffening concept and novel hybrid

joints application that has demonstrated sufficient benefits in terms of airframe weight and

manufacturing costs reduction

y Unidirectionally-reinforced universal attaching elements based on overlapped intersectional

elements for reliable joining of such main load-carrying elements as wing spar, skin, ribs, fuel

tanks, etc. with each other

y Load-carrying components (panels, rods, fairings, etc.) made of standard braided carbon or glass

sleeves that permit to realize any reinforcing angle(s) and fiber volume content in composite

structure

All these make us a strong partner for development of innovations in composites design.

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Advanced Strength AnalysisThe pathway for reliable and efficient design of composite structures

In the frame of composite structure design and manufacturing process development it is important

to ensure allowable level of residual manufacturing stresses, which could appear at curing or/and

assembly stages. To estimate potential residual stresses in the very beginning of structure design we

have developed:

Strength Analysis with Regard for Manufacturing History

Composites heterogeneity, variability of constituents’ performances and some other factors lead to

sufficient variation of composite material characteristics. That’s why an extra safety factor equal to

1.15…1.25 is used in design of aviation composite structures. Nevertheless, this approach is inefficient

in terms of both structure safety and cost efficiency.

We have developed and successfully validated the method for determination of the coefficients

of variation of physical and mechanical characteristics of arbitrarily-reinforced composite material

based on the results of standard material characterisation tests. It gives us a possibility to assign

reasonably an extra safety factor for composite structure design.

In turn, the use of reasonable safety factor at the design stage will ensure minimal weight and cost of

composite structure for specific loading and operation conditions as well as will increase efficiency

of composites application.

Accurate Definition of Safety Factor to Be Used in Composite Structure Design

y Universal phenomenological model of polymer resin curing kinetics

y Method for determination of mechanical characteristics of arbitrarily-reinforced composite

material at any moment of the curing cycle

y Model of thermal warping of laminated composite panels and profiles

y Theory of bending and twisting of thin-walled composite profiles of open/closed cross-section

with variable parameters along the profile length

y Method for determination of assembly stresses/strains that appear as a result of warped

composite panels installation to the load-bearing frame

y Structural and technological solutions for increasing of interlaminar shear strength in thick

composite panels to avoid delaminations caused by thermal and shrinkage stresses

We made a step towards advanced strength analysis of composite structure taking into account

composites characteristics variability and structure manufacturing history

What we do: y Perform all types of composite structures strength analysis

y Study composite structure stress-strain state under thermomechanical loading

y Realize Finite Element Analysis of composite structures

Abovementioned analytical models and algorithms are realised in the software, which allow efficient

composite structure design and optimal manufacturing process development taking into account

expected residual stresses.

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Non-Standard Approaches in Strength Analysis

Sometimes, for design or research purposes it is required to perform non-standard strength analysis

of composite structures or elements that could not be realized using available FEA software.

We have an experience in development of tailored analytical models for composite structures

strength analysis and their implementation in the software. Among others, we have successfully

solved the following tasks:

Combination of tailored analytical models and finite element modelling in advanced simulation

software increases design efficiency and shortens product time-to-market

Finite Element Analysis of Composite Structures

Our researchers have long-term experience in finite element analysis of complex aerospace

structures with the use of advanced simulation software like ANSYS, NASTRAN, ABAQUS, COSMOS,

etc. We are strong in:

Advanced Strength AnalysisThe pathway for reliable and efficient design of composite structures

What we offer: y Analytical and FEM-based strength analysis of composite structures of any complexity

y Development of tailored analytical models and software for composite structure strength analysis

y Creation of rational structural solutions of hybrid composite-metal parts based on FEA

y Modelling of heat conduction through the laminated composite shell during the curing cycle

taking into account exothermic effect of polymerization

y Modelling of stress-strain state of repaired composite/metal structure and repair composite patch

taking into account change of composite patch performances during the curing cycle

y Modelling of stress-strain state of hybrid composite-to-metal joints with longitudinal and

transversal micro-fasteners

y Modelling of physical and mechanical characteristics of braided and transversally-reinforced

laminated composites

All developed analytical models were experimentally validated and ensure accurate results.

y Linear/non-linear static and dynamic analysis of composite structures of any complexity, which

are subjected to multi-axial loading and temperature exposure

y Improved strength analysis of adhesive, mechanical and hybrid joints

y Buckling analysis and determination of natural frequency of vibration for composite structures

y Analysis of temperature fields in composite structures in case of steady-state or unsteady heat

transfer

High level of reliability and accuracy of simulation results is guaranteed through reasonable selection

of analysis nature and finite elements type(s), application of correct loading and bonding conditions,

as well as continuous monitoring of results accuracy and relevant optimization of finite element

mesh density.

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




To facilitate composites application, our researchers focus on “out-of-oven” curing of large-scale

composite structures by means of self-heated tooling application. This approach enables to

drastically reduce energy consumption and manufacturing costs.

For these purposes, we have developed and experimentally validated:

Energy-efficient Tooling for Composites Manufacturing

In case of composites, manufacturing process parameters and curing profile make significant

influence on prefabricated structure quality (i.e. mechanical characteristics, shape and dimensions).

We have developed analytical models and algorithms that enable to build curing profile

(temperature(s), heating/cooling rate(s), etc.) for specific composite structure, which will:

Development of Optimal Curing Profile for Composite Structure

y Thermodynamic model of unsteady heat transfer in composite components and self-heated

tooling

y Algorithm for selection of tooling resistive layer parameters to ensure required thermal field

y Methods and algorithms for precise temperature field control

y Advanced mathematical model for tooling lifetime assessment

Precise developent of curing profile and self-heated tooling application guarantee high quality of

large-scale composite structure as well as energy- and cost-efficiency of manufacturing process

What we do: y Study composites curing mechanisms and their influence on prefabricated structure characteristics

y Develop new solutions for large-scale composite structure manufacturing

y Carry out research on composite structures maintenance and repair

Using abovementioned models and algorithms we are able to design self-heated tooling that will

guarantee required geometry of prefabricated composite structure with minimal energy consumption

during the whole tooling lifetime.

We also have an experience in design and manufacturing of flexible silicon-based heating blankets

and their application for manufacturing and repair purposes.

y Guarantee the required structure quality and parameters

y Minimize and control residual stresses in the structure

y Minimize curing cycle duration and energy consumption

Directly at the stage of composite structure design, this methodology also enables to:

y Assess the possibility to guarantee the required structure quality or develop recommendations

for structure redesign

y Select appropriate process/tool for structure manufacturing

y Substantiate structure acceptance requirements in terms of allowable defects

Composites ManufacturingEnergy-efficient processes and tooling for high-quality production

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Assessment of Residual Strength of Damaged Composite Panels

Being widely used in airframe, composite laminated panels are frequently damaged and have to be

repaired or even totally replaced depending of their residual strength.

We have developed and experimentally validated analytical model for assessment of residual

strength of composite panel with a surface damage (dents, delaminations, part-through cracks, etc.)

of any shape, dimensions and location. The key model assumption consists in incapability of material

in the damaged area to take up and transfer the loads.

Using this model the maintenance engineer could make a reasonable decision regarding further

operation, repair or replacement of damaged panel taking into account its class (primary, secondary,

non-load bearing) and residual strength.

Also, it is possible to develop valid guidelines for surface damages repair taking into account both

structure characteristics and defect parameters.

Development of efficient maintenance procedures and improvement of repair techniques are the key

issues to increase economic efficiency of composite structures operation

Advanced Design of Composite Patch Repair Process

Composite patch repair is a widely used and efficient technique for surface damage repair in both

composite and metal structures.

To guarantee high-quality patch repair with minimal time, costs and influence on repaired structure

characteristics we are able to:

Composites MaintenanceEnergy-efficient processes and tooling for high-quality repair

What we offer: y Development of energy- and cost-efficient manufacturing processes and tooling for composites production

y Development of guidelines and recommendations for composite structure maintenance

y Development of efficient patch repair processes for damaged composite and metal structures

y Select the most suitable materials (sub-layer, adhesive, composites) to guarantee repair efficiency

and long-term reliability

y Design the repair patch of optimal shape and dimensions with stepwise change of thickness to

ensure the strength restoration and minimal increasing of the structure weight

y Develop optimal curing profile to minimize residual stresses in the repaired structure

y Develop repair procedure(s) to be followed by repair technician

For these purposes we use advanced analytical models and complex algorithm for patch repair

process design developed and experimentally validated by our researchers.

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Composites TestingFrom material characterization to component full-scale tests

The Department has a great experience in testing of various composite structural elements under

different static, dynamic and fatigue loading conditions. Recently, we have successfully realized

experimental investigation of hybrid composite-to-metal joints, wafer panels and other composite

structures for aerospace application.

We have experience in:

Static, Dynamic and Fatigue Tests

The Department has all required facilities to test standard composite coupons and determine

physical and mechanical characteristics of all available composite materials. Tests are performed

in accordance with international standards (ASTM, DIN, GOST, etc.) or proprietary methods and

techniques developed by our researchers (if standards are unavailable). Among them are:

Material Characterization

y Design of experiment (including selection of appropriate sample shape/dimensions, static/

fatigue loading conditions, etc.)

y Design and manufacturing of testing fixtures (if required)

y Realization of experiment in accordance with all standard requirements for composites testing

y Processing and reporting of experimental data

To support design and manufacturing activities we perform a full range of composite structure tests

following international standards and proprietary methods developed by our researchers

What we do: y Perform standard tests for determination of composites physical and mechanical characteristics

y Develop and validate new methods/techniques for composites characterization

y Design and realize static, dynamic and fatigue tests of composite structures of any complexity

Careful experiment design and preliminary FEM analysis ensure accurate correspondence of sample

fixation and loading contitions to component operation in real structure. Detailed design of testing

fixtures helps us to avoid non-nominal failure modes and to guarantee test results validity.

y Tensile, compression, shear and bending tests of composite coupons

y Experimental determination of shear and bearing strength of composites

y Shear and pull-off tests of adhesive joints

y Measurement of composites dielectric characteristics

We also perform experimental data processing and provide reports following the customer

requirements.

Application of certified equipment and long-term experience of the Department researchers

guarantee the validity and accuracy of test results.

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Full-Scale Tests of Large 3D Components

Testing of large composite components is extremely important and expensive process. The key task

is to ensure realistic component loading and to avoid inappropriate failure(s) that do not correspond

to operation conditions. We pay a lot of attention to experiment design and usually start it with finite

element analysis of component behaviour during testing. Based on the simulation results, we:

To ensure the validity of complex composite structures test we pay great attention to experiment design

and apply FEM analysis of component behaviour during testing

Our Manufacturing and Testing Capabilities

Our Laboratory is equipped with certified facilities and tools required for composite structures

manufacturing (samples, sub-components, and small-scale components) and further static and

dynamic testing:

Composites TestingFrom material characterization to component full-scale tests

What we offer: y Composite material characterization services

y Design and planning of non-standard test of composite structures and components

y Realization of static, dynamic and fatigue tests of composite structures and components

y Manufacturing facilities: 3D laser projection system, autoclave, ovens with different temperature

ranges, vacuum system for room-temperature curing and machining facilities

y Measuring equipment: thermal imager, RLC meter, durometer, dilatometer, cathetometer, etc.

y Tensile testing machine and automatic strain measuring system

We also have an access to the following University facilities:

y Determine how to fix component in the testing machine to ensure the best correspondence to

its real operation conditions

y Determine areas of maximal stresses/potential failures and points for installation of strain gauges

and measuring equipment

y Calculate the required rigidity and strength of test jig elements required for appropriate

component fixation and loading

After all this work done, we design and manufacture tailored test jig, perform composite component

and test jig assembly and installation to the testing machine, and realize planned test procedures.

Such comprehensive approach guarantees successful testing of complex composite structures.

y Structural test hall equipped with precise hydraulic loading systems (up to 100 kN/m2) and wide

range of hydraulic and electromechanical testing machines for static and fatigue tests

y Scanning electron microscope REM-106, transmission electron microscope PEM-100-01, optical

microscope Neophot 30, X-ray diffractometer DRON-3M

y Subsonic and supersonic wind tunnels with automated control and registration of flow parameters

for 1-4 Mach numbers wind tunnel tests

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Key Research Areas

KhAI aims to take a leading position and to be recognized both in the world and in Ukraine as an

excellent research centre involved in composites engineering

What we do

Composites Research at KhAIDepartment of Composite Structures and Aviation Materials

y Composite Materials Characteristics: We focus on composites characteristics modification via

careful selection of specific additives (incl. nano-particles) and develop new time- and cost-

efficient techniques for composites characterization applying invariant-based theory

y Mechanics of Composite Materials: We explore different aspects of composite materials

mechanics to apply them effectively for computational and engineering problem solving

y Optimal Design of Composite Structures: We develop analytical models, optimization algorithms,

and tailored software to simplify and speed-up of typical structures design (panels, rods, shells, etc.)

y Innovative Design Solutions for Composites: We create radically new design solutions like hybrid

composite-to-metal joints to overcome existing barriers and extend composites application

y Efficient Manufacturing of Composite Structures: We improve energy- and cost-efficiency of

composites production through the development and application of optimal/tailored curing

profile together with specially designed self-heated tooling

y Rational Maintenance of Composite Structures: We assess an influence of typical defects on

structural strength to plan efficient maintenance and develop high-quality repair processes with

minimal time/costs and influence on repaired structure

y Reliable Testing of Composite Structures: We carefully analyze composite structures operation

and loading conditions to realize them precisely during testing thanks to the application of

specially designed test jigs and accessories

y Fundamental research projects funded by the Ukrainian Government

y Applied research upon request of Ukrainian and international industrial enterprises

y International collaborative projects (incl. FP6 SENARIO, ALCAS; FP7 WASIS, KhAI-ERA)

Research Partnership and Cooperation

We successfully cooperate with research, academia and industrial partners from aerospace,

automotive, energy, shipbuilding, sport, leisure and other sectors. Today our research cooperation

goes far beyond the borders of Ukraine and covers well-know European and world-wide entities.

Our Team and Capabilities

Our multi-disciplinary team of experienced and young researchers is strong in various aspects of

composite structure life-cycle. Combination of different knowledge and skills gives us a possibility

to solve complex engineering problems in the most efficient way. We believe that our research

excellence and capabilities will make the Department of Composite Structures and Aviation Materials

your reliable partner.

17 Chkalova str.

Kharkiv, 61070

Ukraine

Tel: +38 057 788 44 03




Composites Education at KhAIDepartment of Composite Structures and Aviation Materials

Bachelor and Master Degrees

Degree Programmes and Training Courses

y High-qualified Academic Staff: Being active in education, our staff is widely involved in research

projects and industrial cooperation to strengthen links among research, innovation and education

y Balanced Curricula and Advanced Courses: We carefully design our curricula and continuously

update lecture and practical courses to include the latest research results and industrial

developments in the field of composites

y Wide Use of Information Technologies: Our students receive solid knowledge and practical skills

on advanced software (CATIA, NASTRAN/PATRAN, etc.) application for composite structures

design and strength analysis

y Modern Education and Training Facilities: The Department has 3 Laboratories intended

specifically for education purposes and well-equipped Research Laboratory that has all certified

facilities and tools required for composite structures manufacturing and testing

y Students’ Involvement into R&D Activities: We actively involve our students into industry-driven

and contractual research to provide them hands-on experience

y Industrial Internships: During the study period, our students have several short-term internships

at leading Ukrainian state enterprises and private companies dealing with composites application

in different sectors

y Support of Students’ Mobility: We support students’ individual mobility and actively participate in

ERASMUS+ European Programme to open access to the best European Universities for our students

Our strategic goal is to train graduates who are competitive at the global market, have up-to-date

knowledge and skills, ready for team work and aimed on lifelong learning

We offer 4-years Bachelor and 2-years Master Degree programmes in “Design and Manufacturing of

Composite Structures”. Every year we graduate 20+ students who easily get a job at state enterprises

and private companies focused on production of aircrafts, boats and yacht, medical equipment, sport

and leisure goods, etc.

PhD degree

We offer Doctoral Degree Programmes in two subjects: “Aircraft Design, Manufacturing, and Testing”

and “Mechanics of Deformable Solids”. Since the Department foundation in 1998 15 PhD thesis have

been prepared and defended by our full-time and distant PhD students.

Our Key Principles

Tailored Courses for Industrial Enterprises’ Staff

We organize short-term training courses on composite structures design, manufacturing,

maintenance and repair on request of industrial enterprises. We are ready to adapt our trainings for

your specific needs and provide them on-site.

Education

Research

Internationa-lization

Innovation

composite structure design - khai · 2018-08-27 · optimal design of composite structures y...

Documents