Page 24 - Automotive Solution for Automotive

Reducing Weight

Improving Simulation Accuracy Rate of High-Tensile Steel Sheet Press Verification and Validation of Simulation Results for Uniaxial Tensile
Forming Simulations that Consider the Bauschinger Effect Testing of Composite Materials

High-tensile sheet steel has attracted attention as one way to improve fuel efficiency by enabling lighter weight transport equipment using Carbon fiber reinforced plastics (CFRPs) and other composite materials have started being used to reduce weight in an effort to reduce the
thinner materials. Shape defects tend to occur after press forming high-tensile sheet steel, which can cause problems by requiring large amounts environmental impact of automobiles and other transport equipment. Unlike metal materials, the internal complexity of composite materials is
of time and money to create the press dies. In recent years, advancements in computer-aided engineering (CAE) analysis technology have known to result in complex failure behavior that depends on the direction of the primary stress axis, which makes it difficult to establish accurate
improved the accuracy of predicting springback, a phenomenon that can cause shape defects. CAE analysis is also used to create dies for press strength design models. Computer-aided engineering (CAE) analysis is widely used for structural simulation during design and development of
forming and could potentially achieve shorter development times and significant cost savings. transportation equipment. Increasing the accuracy of CAE analysis is expected to improve the efficiency, and lower the cost of development and
In this example, material properties data obtained from uniaxial tensile tests and in-plane reverse loading tests performed with a Shimadzu is also expected to improve the reliability of complex or large structural members that are difficult to evaluate by actual measurements.
Autograph precision universal testing machine was used to successfully improve the accuracy of simulating press forming of automobile parts To confirm the reliability of results obtained from CAE analysis, it is considered important to verify and validate (V&V) the results by comparing
(actual panels) with complex shapes. them to actual measurements performed under the same conditions as the CAE analysis model. It is also becoming a general requirement of
Initial deformation
society that products be designed based on both CAE analysis and actual measurements. This example describes verification and validation (V&V)
Elasticity line
Press Forming Steel Plates and Springback Bauschinger Effect
Offset line of results from CAE analysis and actual measurement of a woven thermoplastic CFRP material.
If an initial load causes plastic deformation
Compression False -Spring Back-
in a metal material, and then a load is σYA Y A
applied in the opposite direction, the Stress (MPa)
Upper Die Includes error absolute value of the compressive yield Identification of the Material Constant and Verification of Evaluation of Strain Distribution within Microscopic Areas
stress σYB will be smaller than the the Analysis Model
0
absolute yield stress σYA applied during
Steel Plate Ideal Shape initial loading. That property is referred to Strain (%)
as the Bauschinger effect. By creating a σYB Y B AGX-V Series
Lower Die No error material model based on that property, the Precision Universal Testing
springback phenomenon of steel plates can Sample Machine
be predicted with high accuracy. Elasticity line during
unloading
Offset line
Creating a Model of
the Actual Panel Simulation Accuracy Rate (%) = NP/18 × 100 TRViewX (Customized)
NP: Number of points on actual panel within ±0.5 mm error inspeXio SMX-225CT HR Plus Non-Contact Elongation and
Microfocus X-Ray CT System Width Sensor
*Simulation Accuracy Rate: Percent of points where the perpendicular distance between the actual panel and simulation results is within ±0.5 mm.
Acquisition of Measurement Data (Uniaxial Tensile Test and In-Plane Reversed Stress-Strain Characteristics Data)
Sending Structural Data
Applicable area Overview of Analysis Model
Identifying Shape Parameters for
Microscopic Structures Creating a Fabric Model
SSG Clip-On by Image Processing
Extensometer
SIE-560SA TRViewX
Automatic Non-Contact Elongation
Extensometer and Width Sensor
General-purpose default AGX-V Series Strain Gauge Type Shape of
characteristics data used Precision Universal Testing Machine Width Sensor Jig for Evaluating Bauschinger Effect rectangular model Model of center area of sample
(1/4 symmetric model) (Red: Laterally-oriented fiber bundles;
Actual Panel CAE Analysis Results Blue: Longitudinally-oriented fiber bundles)
Simpleware® ANSYS® & Multiscale.Sim®
Front side Front side Sample shape actually
Model 1 Model 2 measured
(Using default structural data) (Using X-ray CT measurement data)
DIC Analysis ε
Results xx
Actual panel Blue Pass
Default values Red Fail Model 1 Model 2 Just before failure
Model that represents fiber Rigorous model using structural
Actual Panel CAE Analysis Results Back side Back side undulations as ideal sine curves data obtained by X-ray CT Actual measurements
Front side Front side
Model 2 ε
Actual panel Blue Pass Model 1 Zooming Analysis (CAE Analysis) Results yy DIC Analysis (Actual Measurement) Results
Default values Red Fail
Back side Back side
Perpendicular distances between actual panel and simulation results ε yy
Perpendicular distance between actual improved significantly, with the simulation accuracy rate increasing to 61 %. Homogenized Analysis Homogenized Analysis Uniaxial Tensile Tests ε xy
panel and simulation results is large. (Model 1) (Model 2) (Actual Measurements)
28 % simulation accuracy rate is low. Performing Virtual Materials Testing Longitudinal Consistency Longitudinal Consistency
with Actual
with Actual
Elasticity Measurements Elasticity Measurements Longitudinal Elasticity
(GPa)
(GPa) (%) (GPa) (%)
· Enables press forming simulation that considers the Bauschinger effect. ANSYS® & Multiscale.Sim® 32.56 58.7 51.75 93.3 55.46 Both analysis and actual measurement results were
consistent in showing alternating low and high strain areas
· The Bauschinger effect can be evaluated in steel plate materials using a general-purpose precision universal testing that correlated to the fiber spacing in fiber bundles.
machine, rather than a dedicated system. · Structural data from CFRP woven materials can be used to create a CAE analysis model. The indicated data was obtained jointly by Shimadzu
Corporation and Cybernet Systems Co., Ltd. from uniaxial
· Enables offering testing systems that can measure tensile elasticity, r-values, n-values, and plastic strain dependence of · Reasonableness of material constant can be evaluated. tensile simulation of a composite material.
Shimadzu obtained mechanical property values and internal
elasticity, for example. · Reasonableness of various component strains within microscopic areas can be evaluated. structural data and Cybernet Systems performed the CAE
analysis.
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