Overcoming the Challenges of Composite Design through Simulation

Keywords: Vehicle Development, Composite Materials

Composite materials have been used

in the aerospace industry for many

years due to their lightweight and high

performance characteristics, but the issue

of product weight is not limited to aircraft.

Automotive manufacturers are increasingly

viewing the material as a method of

minimizing mass and maximizing fuel

economy.

The material is not without its design

challenges. Composite ply layer stacking

order and fiber direction creates a huge

number of design variables to take into

account when simulating complex events

such as crash. Furthermore, the inherent

high cost of the material can lead many to

see composites as the reserve of high-end

sports vehicles.

UK based automotive design company,

Gordon Murray Design (GMD) believes

that composite materials can play a much

larger role in the manufacture of vehicles

and to prove its case, the company has

developed 'iStream', an efficient process for

manufacturing low and high volume cars

from lightweight mixed materials.

The iStream process seeks to reduce

all costs associated with developing a

vehicle, from factory development and

assembly to tooling design and end of life.

Whereas the traditional approach to vehicle

manufacturing sees stamped steels used for

the body structure, GMD's innovative iStream

manufacturing process uses lightweight

composite panels bonded to a tubular

metallic frame.

IndustryAutomotive

ChallengeComposite material modeling for a innovative new vehicle platform

Altair SolutionExtensive use of simulation technology to understand the behavior of the material under crash loads

Benefits•Accurate simulation of composites•Lighter, fuel efficient vehicles

Key Highlights

Success Story

“Working directly with the Altair ProductDesign team and how they integrate and interact with Altair’s software division and all the other components of the organization has been invaluable to us."

Simon Maher, Senior Stress & Materials Engineer, Gordon Murray Design

iStream is being developed as an intellectual

property for GMD which it intends to license

out to companies wishing to diversify into

the car market. However, in order to make

iStream successful, GMD must prove that

a vehicle which relies on composite panels

for much of its structural integrity can meet

strict performance targets. To do this, GMD

has developed a number of demonstrator

vehicles including the T.25 and T.27 that

utilize the iStream philosophy.

Selecting an Experienced Simulation Development PartnerGMD is a small, focused and highly talented

company with a huge amount of vehicle

engineering pedigree and experience.

The iStream project requires a deep

understanding of the behavior of composite

material and how it can be accurately

modeled to prove its suitability as a

structural component.

GMD is an established user of Altair's

HyperWorks suite of simulation technologies.

When the company was looking for an

external partner with simulation expertise,

Altair ProductDesign, was

the natural choice. Altair

is able to link its software

development business

with its engineering

services, allowing Altair

ProductDesign to apply

experiences gained during projects to

directly influence the functionality and

accuracy of the software suite. This was a

key decision factor for GMD who saw the

interaction between the two businesses as

a crucial differentiating factor over other

product development companies.

Streamlined Model BuildAltair ProductDesign was asked to improve

the virtual modeling of the composite

materials used in iStream to achieve

correlation with physical

test results.

The first task was to build

accurate material models

for the iStream sandwich

panels. The panels are

considerably lighter than metal alternatives

while maintaining strength and stiffness as

well as being inexpensive to maintain and

avoid many corrosion issues.

The T.25 Demonstrator Vehicle Showing the iStream Frame

T.27 Utilizes iSteam to Create a Lightweight Electric Drive Vehicle

Altair ProductDesign was asked to improve the virtual modeling of the composite

materials to achieve correlation with physical

test results

To effectively model the structure requires

detailed modeling of the glass fiber

laminates, soft core and the structural

adhesive used to bond the panels to the

frame. GMD tasked Altair ProductDesign

with creating a highly tuneable CAE model

of an iStream chassis in order to appraise

the load paths in frontal and side dynamic

impacts. Using Altair's HyperWorks suite,

Altair ProductDesign suggested a finite

element modeling method which utilized 1D

beam and shell elements

for different parts of the

vehicle structure with much

of the model creation

work conducted by Altair's

offshore capability to speed

up this time consuming phase.

This method allowed the analysis stage to

directly inform the design stage through the

creation of representative virtual models

of the composite material developed much

earlier than in a standard development

process. Design direction could be quickly

explored, manipulated and assessed but

without creating compute intensive analyses.

Accelerating the analysis process enables

GMD to rapidly investigate more design

variations and achieve the optimal design

configuration in a shorter timescale.

Defining Material BehaviorUnderstanding the behavior of the

composite materials is a crucial step in the

development cycle as the level of knowledge

within the automotive industry is not as

mature as with metallics.

Once a level of confidence

in the material behavior

at a component level is

achieved, the material

simulation will move

beyond discrete components and onto a

system characterization level. Here, sub

and full systems are analyzed, allowing the

engineers to view the interaction of each

part on the surrounding components during

loading.

Altair ProductDesign and GMD will carry

out a range of virtual simulation tests using

HyperWorks' RADIOSS solver to define

the material's behavior under various

loading conditions including crash. The

virtual testing process is performed with

an understanding of the physical test

requirements to ensure that results can be

effectively correlated without the need to

repeat tests unnecessarily.

Conclusion: Developing Innovative Vehicles with Added ConfidenceAs the analysis and correlation to physical

test stages of the project become finalized,

Altair ProductDesign will continue to

work with GMD and develop the iStream

structure to improve crash performance.

The use of advanced materials require

innovative methods of design and validation

to ensure that they perform at the highest

levels without compromise to safety. The

combination of simulation expertise from

Altair ProductDesign and the vehicle

development and composite expertise of

GMD has been a highly effective partnership

that will help to prove the value of the

innovative iStream process.

Gordon Murray Design was established in 2007 in the UK to develop an innovative and disruptive automotive manufacturing technology trademarked iStream, the design and prototyping of the T.25 City Car was central to the validation and development of iStream.

About Gordon Murray Design

Comparing Virtual Crash Model with Physical Test of the iStream based T.32 Nose Cone

Altair ProductDesign will continue to work closely

with GMD and develop the iStream structure to improve

crash performance

Find out more about Gordon Murray Design: www.gordonmurraydesign.com

Find out more about Altair ProductDesign:www.altairproductdesign.com

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Success Stories

Altair empowers client innovation and decision-making through technology that optimizes the analysis, management and visualization of business and engineering information. Privately held with more than 1,800 employees, Altair has offices throughout North America, South America, Europe and Asia/Pacific. With a 25-year-plus track record for innovative product design and development, advanced engineering software and grid computing technologies, Altair has more than 3,500 corporate clients representing the automotive, aerospace, government and defense, and consumer products verticals. Altair also has a growing client presence in the life sciences, financial services and energy markets.

Altair ProductDesign is a global, multi-disciplinary product development consultancy of more than 700 designers, engineers, scientists, and creative thinkers. As a wholly owned subsidiary of Altair Engineering Inc., this organization is best known for its market leadership in combining its engineering expertise with computer aided engineering (CAE) technology to deliver innovation and automate processes. Altair ProductDesign firmly advocates a user-centered, team-based design approach, and utilizes proprietary simulation and optimization technologies (such as Altair HyperWorks) to help clients bring innovative, profitable products to market on a tighter, more efficient time-scale.

HyperWorks is an enterprise simulation solution for rapid design exploration and decision-making. As one of the most comprehensive, open-architecture CAE solutions in the industry, HyperWorks includes best-in-class modeling, analysis, visualization and data management solutions for linear, nonlinear, structural optimization, fluid-structure interaction, and multi-body dynamics applications.

About Altair

www.altairproductdesign.com

www.altairhyperworks.com