Sumitomo Case Study (1)
SUMITOMO RUBBER
TRANSPORTATION & MOBILITY CASE STUDY
Challenge
Engineers in Sumitomo Rubber’s Material Department needed to improve tire performance to help meet more stringent fuel economy/CO2 regulations, as well as new tire labeling standards for rolling resistance and wet grip.
Solution
Using Abaqus FEA and other simulation tools and methods, the engineering project team developed a multi-scale simulation that was able to analyze material behavior at the micro- and nano-scales within the tire rubber’s polymer-filler matrix.
Benefits
By creating innovative simulation techniques, engineers accurately predicted material behavior that can’t be measured using physical testing, shortened the tire development cycle while increasing its efficiency, and improved tire performance.
Figure 1. In earlier research, Sumitomo engineers used Abaqus to conduct tire simulations such as rolling resistance (top left, contour section of tire), hydroplaning and mode analysis (bottom, four views).
Simulation helps examine rolling resistance The U.S. auto industry has been abuzz about CAFE (corporate average fuel economy) standards since aggressive targets were recently set for the fleet: 34.1 mpg by 2016, increasing to 54.5 mpg by 2025. Regulations in the EU, Japan, and China—already higher than the U.S.—are also scheduled to increase sharply by 2020. The new numbers shift fuel-efficiency initiatives into the fast lane for engineering design teams at car-makers and suppliers worldwide. Performance capabilities—such as advanced injection, combustion and exhaust systems, hightech lubricants, lightweight materials, and aerodynamic enhancements—are a major focus in pursuit of reduced carbon emissions. And so are tires, which also have an important contribution to make in meeting the new goals. Roughly two-thirds of the oil consumed in the U.S. serves to power the country’s 250-million-vehicle fleet. Of that total (for cars and trucks combined, according to the International Energy Agency), about 20 percent is dedicated to simply overcoming the friction of tires rolling on pavement. Rolling resistance (RR), as this property is called, is dependent on two major factors: tire design—which includes size, structure, and material makeup; and operating conditions, encompassing inflation pressure, vehicle load, ambient temperature, rotating speed, and alignment. Tire makers have already improved rolling resistance by 25 to 30 percent over the last twenty years. Still, further advances in tire performance, and throughout the vehicle, are needed to achieve the new fuel-economy rules. But engineers are optimistic. They generally agree that advances in RR can cut fuel consumption by an additional three percent—and that those changes are well within current technical and financial capabilities. Improving tires, as compared with other automotive systems, is considered by most in the industry to be a relatively low-investment way to enhance automotive fuel efficiency.
Over the years, engineers in the research and development department at Sumitomo Rubber Industries in Kobe, Japan have played their part in RR-improvement studies. Efforts led by their simulation team have advanced both the structure and material makeup of tires. But the urgency of their redesign efforts has been upped by future standards, as well as an existing 2010 agreement among tire manufacturers to introduce a graded tireperformance labeling system. If squeezing better performance out of rubber tires was simply a matter of minimizing friction (as rubber deforms and then recovers, tires create heat which gives up energy), the engineering challenge would be easier to solve. But performance is also a function of safety, accomplished by making the tire grip the road, especially in wet conditions. From a design point of view, “wet grip” (as it’s known), is the functional opposite of RR. So the design challenge becomes one of tradeoffs: how to minimize friction for better RR, versus how to maximize grip to keep drivers safe. The secret to balancing these two opposing physical principles lies in the rubber. “The performance of a tire depends on the characteristics of various compounds and the complicated relationships between structures at the micro- and nano-levels,” says Naito Masato, assistant manager in Sumitomo’s Material Department.
“We chose Abaqus because it can handle large-scale simulations and has the capabilities to analyze the large, non-linear material deformations of rubber.” Naito Masato, assistant manager, Sumitomo Material Department
Rubber tires consist of an intricate mix of polymers, fillers, and cross-linkers. Polymers, known for their softness and elasticity, form the dominant matrix and are structured in strands of molecular-sized beads that can number in the hundreds of thousands. Silica and carbon—the fillers—serve as reinforcing agents and are added for strength and to improve wear. Dispersed through the matrix, fillers form bonds with the polymers (through intermediary coupling agents, or functional groups, in the polymer molecule). This makes the material more rigid. The spacing of the silica in the polymer matrix, and the position of the bonding between the two materials, inhibits the wasteful deformation and heat generation that is ultimately responsible for the tire’s rolling resistance. “We have a long history of simulating tires,” says Masato. “But until recently, it was not easy to examine these relationships in greater detail to further improve our material designs.” For more than fifteen years, Sumitomo engineers have been using Abaqus finite element analysis (FEA)—which is part of the Dassault Systèmes 3DEXPERIENCE technology portfolio under the SIMULIA brand—to conduct tire simulations (see Figure 1). “We chose Abaqus because it can handle largescale simulations and has the capabilities to analyze the large, non-linear material deformations of rubber,” says Masato. “The software is highly accurate and has a wide variety of allpurpose material models that are easy to calibrate.”
New simulation methods look deeper into the rubber Early material simulations were instrumental in helping Sumitomo engineers improve overall tire performance. But with market pressure rising, new techniques were needed to more closely understand the complex material behavior that occurs when the rubber meets the road.
For this purpose, the team developed a multi-scale simulation methodology—called 4D NANO DESIGN—which looked at tire materials at increasing depths of magnification. At the first level, FEA predicts micrometer-scale (1/1,000 mm) deformation of the rubber, including the exact location of the energy loss in the material. A molecular dynamic (MD) simulation, next analyzes the three-dimensional arrangement of silica particles and the bonding between the polymer and silica (or other compounds) at the nanometer scale (1/1,000,000 mm). A molecular orbital (MO) simulation at the sub-nanometer level (1/10,000,000 mm) then examines the reactivity (or electronic and energy status) of the materials (see Figure 2). “The material behavior of rubber tires could not previously be simulated with this degree of accuracy,” says Masato. For the FEA micrometer-scale analysis, the team needed to create a finite element model (FEM) that accurately reproduced the three-dimensional structure of the rubber, including the distribution and exact location of filler through the polymer matrix. This was done by collecting sophisticated test data: dynamic testing provided details of polymer behavior; transmission electron microscopy (TEM) and x-ray scattering were used to reveal 2D micrometer- to nanometer-scale structural details; and transmission electron micro tomography helped map the 3D structure. Because the computational challenges were formidable (due to the size of the matrices involved), Abaqus Standard’s newly introduced iterative solver was employed in a highperformance computing environment to simulate the response of the microstructure accurately and efficiently. The FEA results showed that the highest heat (the cause of rolling resistance) was generated where the filler particles contacted each other (see Figure 3). This finding highlighted the importance of achieving uniform dispersion of the filler throughout the polymer matrix.
Figure 2. The Sumitomo engineering team’s multi-scale simulation predicts the material behavior of tires at increasing magnification: Abaqus FEA was used to generate loading on tire rubber at the millimeter scale; these loads were utilized to predict material behavior at the micrometer scale, where excess heat is generated in the rubber; a Molecular Dynamics (MD) simulation, at the nanometer scale, was then performed using specialized soft-materials software; a final Molecular Orbital (MO) simulation analyzed the energy state of the silica-polymer bonding at the sub-nanometer level.
Guided by the FEA results, a molecular dynamics simulation (using COGNAC, a specialized softmaterial software that is part of OCTA) evaluated filler dispersion techniques and calculated polymer formulations with evenly distributed filler (which would lead to improved RR) (see Figure 4). The engineering team then worked with the development manager to ensure that the suggested materials fit within accepted manufacturing protocols and costs. This process helped avoid laborious trial-anderror polymer synthesis-and-testing cycles. The MO simulation examined the reactivity of the chosen materials and further optimized the rubber structure.
Sumitomo’s new 4D NANO DESIGN technology allows the company to look into tire performance in totally novel ways. “Our material development process is unique. We can now predict tire performance at the micro- and nano-levels. This can’t be done using physical testing,” says Masato. “Simulation has shortened our product development cycles and made our process more efficient.”
Figure 3. Using Abaqus FEA, a 459×712×489 nanometer block of rubber (far left) was modeled with approximately 10 million hexahedral elements, which separately considered polymer (green) and filler (red) and accounted for both non-linear viscoelasticity and elasticity characteristics while simulating tensile deformations. An enlarged view of the filler alone is shown (middle). In the strain distribution (far right), the rubber was deformed and where polymer was sandwiched between unevenly dispersed filler there was evidence of large strains (red), indicating the generation of heat, which increases rolling resistance.
Tires designed using these new methods—with better RR and improved wet grip—are already on the road. This means that vehicles are that much closer to meeting new fuel economy and CO2 emission standards. And further improvements in tires are likely just around the corner. “We anticipate that our new process will make a significant contribution to the more effective development of tires in the future,” Masato adds.
Figure 4. In the MD simulation, the dispersion of silica filler (white) in the polymer (blue) is shown in its initial condition (left) and its final condition (right). The distribution of silica influences the strain, generation of heat, and the rolling resistance for each polymer structure.
ENOVIA
3DSWYM
Modeling Apps 3D
SOLIDWORKS
Intelligenc eA pp s
Dassault Systèmes, the 3DEXPERIENCE Company, provides business and people with virtual universes to imagine sustainable innovations. Its world-leading solutions transform the way products are designed, produced, and supported. Dassault Systèmes’ collaborative solutions foster social innovation, expanding possibilities for the virtual world to improve the real world. The group brings value to over 170,000 customers of all sizes in all industries in more than 140 countries. For more information, visit www.3ds.com.
CATIA
tion ma for In
Our 3DEXPERIENCE ® Platform powers our brand applications, serving 12 industries, and provides a rich portfolio of industry solution experiences.
ollaborative Ap l&C ps cia So
GEOVIA
Co
n te
nt &
3DVIA
Europe/Middle East/Africa Dassault Systèmes 10, rue Marcel Dassault CS 40501 78946 Vélizy-Villacoublay Cedex France
S i m u la ti o n
DELMIA
Ap
EXALEAD
NETVIBES
ps
SIMULIA
Asia-Pacific Dassault Systèmes Pier City Shibaura Bldg 10F 3-18-1 Kaigan, Minato-Ku Tokyo 108-002 Japan
Americas Dassault Systèmes 175 Wyman Street Waltham, Massachusetts 02451-1223 USA
© Dassault Systèmes 2014, all rights reserved. CATIA, SOLIDWORKS, SIMULIA, DELMIA, ENOVIA, GEOVIA, EXALEAD, NETVIBES, 3DSWYM, 3DVIA are registered trademarks of Dassault Systèmes or its subsidiaries in the US and/or other countries.
The benefits of multi-scale simulation
TRANSPORTATION & MOBILITY CASE STUDY
Challenge
Engineers in Sumitomo Rubber’s Material Department needed to improve tire performance to help meet more stringent fuel economy/CO2 regulations, as well as new tire labeling standards for rolling resistance and wet grip.
Solution
Using Abaqus FEA and other simulation tools and methods, the engineering project team developed a multi-scale simulation that was able to analyze material behavior at the micro- and nano-scales within the tire rubber’s polymer-filler matrix.
Benefits
By creating innovative simulation techniques, engineers accurately predicted material behavior that can’t be measured using physical testing, shortened the tire development cycle while increasing its efficiency, and improved tire performance.
Figure 1. In earlier research, Sumitomo engineers used Abaqus to conduct tire simulations such as rolling resistance (top left, contour section of tire), hydroplaning and mode analysis (bottom, four views).
Simulation helps examine rolling resistance The U.S. auto industry has been abuzz about CAFE (corporate average fuel economy) standards since aggressive targets were recently set for the fleet: 34.1 mpg by 2016, increasing to 54.5 mpg by 2025. Regulations in the EU, Japan, and China—already higher than the U.S.—are also scheduled to increase sharply by 2020. The new numbers shift fuel-efficiency initiatives into the fast lane for engineering design teams at car-makers and suppliers worldwide. Performance capabilities—such as advanced injection, combustion and exhaust systems, hightech lubricants, lightweight materials, and aerodynamic enhancements—are a major focus in pursuit of reduced carbon emissions. And so are tires, which also have an important contribution to make in meeting the new goals. Roughly two-thirds of the oil consumed in the U.S. serves to power the country’s 250-million-vehicle fleet. Of that total (for cars and trucks combined, according to the International Energy Agency), about 20 percent is dedicated to simply overcoming the friction of tires rolling on pavement. Rolling resistance (RR), as this property is called, is dependent on two major factors: tire design—which includes size, structure, and material makeup; and operating conditions, encompassing inflation pressure, vehicle load, ambient temperature, rotating speed, and alignment. Tire makers have already improved rolling resistance by 25 to 30 percent over the last twenty years. Still, further advances in tire performance, and throughout the vehicle, are needed to achieve the new fuel-economy rules. But engineers are optimistic. They generally agree that advances in RR can cut fuel consumption by an additional three percent—and that those changes are well within current technical and financial capabilities. Improving tires, as compared with other automotive systems, is considered by most in the industry to be a relatively low-investment way to enhance automotive fuel efficiency.
Over the years, engineers in the research and development department at Sumitomo Rubber Industries in Kobe, Japan have played their part in RR-improvement studies. Efforts led by their simulation team have advanced both the structure and material makeup of tires. But the urgency of their redesign efforts has been upped by future standards, as well as an existing 2010 agreement among tire manufacturers to introduce a graded tireperformance labeling system. If squeezing better performance out of rubber tires was simply a matter of minimizing friction (as rubber deforms and then recovers, tires create heat which gives up energy), the engineering challenge would be easier to solve. But performance is also a function of safety, accomplished by making the tire grip the road, especially in wet conditions. From a design point of view, “wet grip” (as it’s known), is the functional opposite of RR. So the design challenge becomes one of tradeoffs: how to minimize friction for better RR, versus how to maximize grip to keep drivers safe. The secret to balancing these two opposing physical principles lies in the rubber. “The performance of a tire depends on the characteristics of various compounds and the complicated relationships between structures at the micro- and nano-levels,” says Naito Masato, assistant manager in Sumitomo’s Material Department.
“We chose Abaqus because it can handle large-scale simulations and has the capabilities to analyze the large, non-linear material deformations of rubber.” Naito Masato, assistant manager, Sumitomo Material Department
Rubber tires consist of an intricate mix of polymers, fillers, and cross-linkers. Polymers, known for their softness and elasticity, form the dominant matrix and are structured in strands of molecular-sized beads that can number in the hundreds of thousands. Silica and carbon—the fillers—serve as reinforcing agents and are added for strength and to improve wear. Dispersed through the matrix, fillers form bonds with the polymers (through intermediary coupling agents, or functional groups, in the polymer molecule). This makes the material more rigid. The spacing of the silica in the polymer matrix, and the position of the bonding between the two materials, inhibits the wasteful deformation and heat generation that is ultimately responsible for the tire’s rolling resistance. “We have a long history of simulating tires,” says Masato. “But until recently, it was not easy to examine these relationships in greater detail to further improve our material designs.” For more than fifteen years, Sumitomo engineers have been using Abaqus finite element analysis (FEA)—which is part of the Dassault Systèmes 3DEXPERIENCE technology portfolio under the SIMULIA brand—to conduct tire simulations (see Figure 1). “We chose Abaqus because it can handle largescale simulations and has the capabilities to analyze the large, non-linear material deformations of rubber,” says Masato. “The software is highly accurate and has a wide variety of allpurpose material models that are easy to calibrate.”
New simulation methods look deeper into the rubber Early material simulations were instrumental in helping Sumitomo engineers improve overall tire performance. But with market pressure rising, new techniques were needed to more closely understand the complex material behavior that occurs when the rubber meets the road.
For this purpose, the team developed a multi-scale simulation methodology—called 4D NANO DESIGN—which looked at tire materials at increasing depths of magnification. At the first level, FEA predicts micrometer-scale (1/1,000 mm) deformation of the rubber, including the exact location of the energy loss in the material. A molecular dynamic (MD) simulation, next analyzes the three-dimensional arrangement of silica particles and the bonding between the polymer and silica (or other compounds) at the nanometer scale (1/1,000,000 mm). A molecular orbital (MO) simulation at the sub-nanometer level (1/10,000,000 mm) then examines the reactivity (or electronic and energy status) of the materials (see Figure 2). “The material behavior of rubber tires could not previously be simulated with this degree of accuracy,” says Masato. For the FEA micrometer-scale analysis, the team needed to create a finite element model (FEM) that accurately reproduced the three-dimensional structure of the rubber, including the distribution and exact location of filler through the polymer matrix. This was done by collecting sophisticated test data: dynamic testing provided details of polymer behavior; transmission electron microscopy (TEM) and x-ray scattering were used to reveal 2D micrometer- to nanometer-scale structural details; and transmission electron micro tomography helped map the 3D structure. Because the computational challenges were formidable (due to the size of the matrices involved), Abaqus Standard’s newly introduced iterative solver was employed in a highperformance computing environment to simulate the response of the microstructure accurately and efficiently. The FEA results showed that the highest heat (the cause of rolling resistance) was generated where the filler particles contacted each other (see Figure 3). This finding highlighted the importance of achieving uniform dispersion of the filler throughout the polymer matrix.
Figure 2. The Sumitomo engineering team’s multi-scale simulation predicts the material behavior of tires at increasing magnification: Abaqus FEA was used to generate loading on tire rubber at the millimeter scale; these loads were utilized to predict material behavior at the micrometer scale, where excess heat is generated in the rubber; a Molecular Dynamics (MD) simulation, at the nanometer scale, was then performed using specialized soft-materials software; a final Molecular Orbital (MO) simulation analyzed the energy state of the silica-polymer bonding at the sub-nanometer level.
Guided by the FEA results, a molecular dynamics simulation (using COGNAC, a specialized softmaterial software that is part of OCTA) evaluated filler dispersion techniques and calculated polymer formulations with evenly distributed filler (which would lead to improved RR) (see Figure 4). The engineering team then worked with the development manager to ensure that the suggested materials fit within accepted manufacturing protocols and costs. This process helped avoid laborious trial-anderror polymer synthesis-and-testing cycles. The MO simulation examined the reactivity of the chosen materials and further optimized the rubber structure.
Sumitomo’s new 4D NANO DESIGN technology allows the company to look into tire performance in totally novel ways. “Our material development process is unique. We can now predict tire performance at the micro- and nano-levels. This can’t be done using physical testing,” says Masato. “Simulation has shortened our product development cycles and made our process more efficient.”
Figure 3. Using Abaqus FEA, a 459×712×489 nanometer block of rubber (far left) was modeled with approximately 10 million hexahedral elements, which separately considered polymer (green) and filler (red) and accounted for both non-linear viscoelasticity and elasticity characteristics while simulating tensile deformations. An enlarged view of the filler alone is shown (middle). In the strain distribution (far right), the rubber was deformed and where polymer was sandwiched between unevenly dispersed filler there was evidence of large strains (red), indicating the generation of heat, which increases rolling resistance.
Tires designed using these new methods—with better RR and improved wet grip—are already on the road. This means that vehicles are that much closer to meeting new fuel economy and CO2 emission standards. And further improvements in tires are likely just around the corner. “We anticipate that our new process will make a significant contribution to the more effective development of tires in the future,” Masato adds.
Figure 4. In the MD simulation, the dispersion of silica filler (white) in the polymer (blue) is shown in its initial condition (left) and its final condition (right). The distribution of silica influences the strain, generation of heat, and the rolling resistance for each polymer structure.
ENOVIA
3DSWYM
Modeling Apps 3D
SOLIDWORKS
Intelligenc eA pp s
Dassault Systèmes, the 3DEXPERIENCE Company, provides business and people with virtual universes to imagine sustainable innovations. Its world-leading solutions transform the way products are designed, produced, and supported. Dassault Systèmes’ collaborative solutions foster social innovation, expanding possibilities for the virtual world to improve the real world. The group brings value to over 170,000 customers of all sizes in all industries in more than 140 countries. For more information, visit www.3ds.com.
CATIA
tion ma for In
Our 3DEXPERIENCE ® Platform powers our brand applications, serving 12 industries, and provides a rich portfolio of industry solution experiences.
ollaborative Ap l&C ps cia So
GEOVIA
Co
n te
nt &
3DVIA
Europe/Middle East/Africa Dassault Systèmes 10, rue Marcel Dassault CS 40501 78946 Vélizy-Villacoublay Cedex France
S i m u la ti o n
DELMIA
Ap
EXALEAD
NETVIBES
ps
SIMULIA
Asia-Pacific Dassault Systèmes Pier City Shibaura Bldg 10F 3-18-1 Kaigan, Minato-Ku Tokyo 108-002 Japan
Americas Dassault Systèmes 175 Wyman Street Waltham, Massachusetts 02451-1223 USA
© Dassault Systèmes 2014, all rights reserved. CATIA, SOLIDWORKS, SIMULIA, DELMIA, ENOVIA, GEOVIA, EXALEAD, NETVIBES, 3DSWYM, 3DVIA are registered trademarks of Dassault Systèmes or its subsidiaries in the US and/or other countries.
The benefits of multi-scale simulation
