1

Material parameter identification of concrete by an impact

(Combination of Radioss & HyperStudy)

by

Vitali Almendinger

2

Agenda

• Company/ Product introduction

• Hammer description

• Measurement/ Simulation principle

• Mesh Size/ Properties

• DOE

• Definition of design variables/ Specifications

• Definition of the responses: characteristic measures of test curve

• DOE results

• Optimization and results

3

Company/ Product introduction

Today DEWALT is a leading brand of professional power tools in the world and

in the last 5 years the fastest growing power tool brand in the world.

Compact Hammers Mid Size Hammers Demolition Hammers

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Hammer description

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Initial Velocity

Gravity

Measurement Points

Measurement/ Simulation principle

BCS mid Nodes

DOF (0,0,1)

Equivalent

Nodes

BCS Block

DOF (0,0,0)

Ram

Drill

Concrete

Core

Concrete

Block

/MAT/LAW1

/MAT/LAW24

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Measurement/ Simulation principle V

elo

cit

y o

f R

am

[m

/s]

Velo

cit

y o

f D

rill [

m/s

]

Time [ms]

Time [ms]

7

Measurement/ Simulation principle

Statistical

Reference

Curve Measurement

Curves

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Mesh Size/ Properties

9

Mesh Size/ Properties

Mesh parameters

• Concrete parts only HEX-Mesh

• Concrete Core constant Mesh size of ̴ 0.3 mm

Properties

• Steel parts Isolid=24

(with Isolid=1, to much Hourglassenergy)

• Concrete parts must have Isolid=1

(with Isolid=24, to much damping)

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Definition of design variables/ Specifications

7 Design variables

• fc (Concrete uniaxial compression strength)

• ft/fc (Concrete tensile strength ratio)

• ν (Poisson’s ratio)

• Ht (Concrete data tensile tangent modulus)

• ky (Concrete plasticity initial value of

hardening parameter)

• Stfac Type20 Ram and Tool (Interface

stiffness scale factor)

• Stfac Type20 Tool Tip and Concrete Core

(Interface stiffness scale factor)

DOE Specifications

• Hammersley

• Number of runs: choose by default (36 runs)

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Definition of the responses: characteristic

measures of test curve

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Max. D

ista

nce

Curvature Length

Pen

e_m

ax

Slope

Response

• Maximum Penetration

• Curvature Length (at a node displacement of 0.15mm)

• Slope

• Max. Distance (of the time axis 6e-4s until 9e-4s)

• Ram velocity at the end

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DOE Results

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Max. D

ista

nce

Curvature Length

Pen

e_m

ax

Slope

Curvature

Length

Slope

Max.

Distance

Ram V_end

Pene_Max C

urv

atu

re

Len

gth

Stf

ac

_R

am

_To

ol

Ma

x.

Dis

tan

ce

Ram

V_

en

d

Pe

ne_

Ma

x

Ht

f c

Stf

ac

_T

ip_

Co

re

f t/f

c

ky

Po

iss

on

’s

rati

o

Slo

pe

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DOE Results /

Optimization

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Optimization

Design variables

• fc (Concrete uniaxial compression strength)

• ft/fc (Concrete tensile strength ratio)

•Stfac Type20 Ram and Tool (Interface stiffness scale factor)

• Stfac Type20 Tool Tip and Concrete Core (Interface stiffness scale factor)

Optimization Specification

• Genetic Algorithm

Statistical

Reference

Curve Start Values For

Optimization

DOE Result

Curves

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Optimization Result

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Thanks for Your Attention!