Prediction of springback in the forming of advanced high strength steel: simulation and experimental study
Dual Phase (DP) steel is categorized as advanced high-strength steels (AHSS) which has tensile strengths ranging from 500 to 800 MPa. DP steel is gaining popularity in automotive applications. It has higher formability than HSLA grades with similar initial yield strengths, but has much higher fin...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2011
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/2764/1/24p%20NORAISHAH%20MOHAMAD%20NOOR.pdf http://eprints.uthm.edu.my/2764/2/NORAISHAH%20MOHAMAD%20NOOR%20WATERMARK.pdf |
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| Summary: | Dual Phase (DP) steel is categorized as advanced high-strength steels (AHSS)
which has tensile strengths ranging from 500 to 800 MPa. DP steel is gaining popularity
in automotive applications. It has higher formability than HSLA grades with similar
initial yield strengths, but has much higher final part strength. With proper design
strategy, Dual Phase (DP) steels offers a great advantage in terms of body weight
reduction and crash performance. One of the major constraints in forming AHSS is the
occurrence of high springback caused by elastic relaxation after loading, which causes
ill-fitting in part assembly and geometric deviation of the intended design. This research
focused on finite element (FE) simulation of the sheet forming of dual phase steel and
the springback prediction. If springback could be accurately predicted, the forming die
could be correctly designed to compensate springback. The material used in this study
was DOCOL 800 DP manufactured by SSAB- Sweden with ultimate tensile strength of
870 MPa and thickness of 0.72mm. The plastic behavior of DP800 was presented by
exponential based constitutive equation known as isotropic hardening. From tensile test,
strain hardening value (n) was 0.308 and strength coefficient (K) was 1319.165 MP. The
FE simulations were conducted for tensile test, U-channel forming and springback
simulation. These simulations were carried out by using general purpose transient
dynamic FE code Lsdyna. The tensile test simulation result indicated the isotropic
hardening material model was suitable for DP800 behavior with standard deviation
value 62.45 MPa between simulation and experiment. Meanwhile, the springback
simulation using U-channel represented the deviation for BHF 10kN, 20kN, 30kN and
97kN were 0.019, 0.071, 0.341 and 0.231. Overall, the result of 20KN BHF applied
indicated the minimum springback in the forming of DP800. |
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