報(bào)告人：

Leroy Gardner教授（結(jié)構(gòu)工程教授、倫敦帝國理工學(xué)院、英國皇家工程院院士）

報(bào)告摘要：

增材制造或3D打印金屬材料在結(jié)構(gòu)工程領(lǐng)域的應(yīng)用前景廣闊。目前，增材制造技術(shù)在結(jié)構(gòu)工程領(lǐng)域取得了一系列新進(jìn)展，主要表現(xiàn)在科學(xué)研究、其他領(lǐng)域經(jīng)驗(yàn)借鑒、工程實(shí)踐等諸多方面。本報(bào)告基于建筑工程領(lǐng)域的要求，針對當(dāng)前最有應(yīng)用前景的“電弧增材制造技術(shù)〞(WAAM)，介紹WAAM薄壁型鋼、不銹鋼結(jié)構(gòu)的材料力學(xué)性能，以及其截面、構(gòu)件、連接、體系的結(jié)構(gòu)性能。圍繞WAAM金屬材料的固有幾何變異性、潛在各向異性，探討其研究與應(yīng)用方面的挑戰(zhàn)?？紤]增材制造技術(shù)對結(jié)構(gòu)優(yōu)化的推動作用，以及二者協(xié)同發(fā)展為結(jié)構(gòu)優(yōu)化帶來的機(jī)遇，討論近期采用增材制造技術(shù)開展結(jié)構(gòu)優(yōu)化的案例。

報(bào)告人簡介：

Leroy Gardner，倫敦帝國理工學(xué)院土木與環(huán)境工程系教授，英國皇家工程院院士。主要從事結(jié)構(gòu)工程教學(xué)、科研與工程咨詢工作，其帶領(lǐng)的研究團(tuán)隊(duì)長期活躍于國際研究領(lǐng)域。Gardner教授是國際鋼結(jié)構(gòu)領(lǐng)域的著名學(xué)者，其研究涵蓋了鋼結(jié)構(gòu)試驗(yàn)、模擬、分析、設(shè)計(jì)、建造等諸多方面?，F(xiàn)已累計(jì)出版4部著作、7篇專著章節(jié)，發(fā)表論文500余篇。Gardner教授是兩本國際期刊的主編，多部《歐洲規(guī)范》《美國規(guī)范》的編寫委員會成員。Gardner教授于2017年榮獲，國際橋梁與結(jié)構(gòu)工程協(xié)會國際結(jié)構(gòu)工程功勛獎(jiǎng)〞（IABSE），并于2021年榮獲美國土木工程師學(xué)會 ( ASCE) Shortridge Hardesty獎(jiǎng)〞

Digital Image Correlation (DIC)

Speckle patterns were applied to coupons (and other tested elements) to provide features for DIC system to capture to allow us to obtain full field strain measurements

Stress-strain curves of machined carbon steel coupons

Carbon steel σ-? response was found to be largely isotropic, with similar mechanical properties to conventionally formed material

stress-strain curves of machined stainless steel coupons

Microstructural analysis of WAAM carbon steel

Microstructural analysis of WAAM stainless steel

From the WAAM stainless steel (FCC), EBSD revealed a strong crystallographic texture, arising from solidification of the printed material under a thermal gradient. This explained the strong anisotropy.

Influence of as-built geometry on key mechanical property

Key 'effective' mechanical properties of as-built (AB) carbon steel?below machined (M) coupons typically by between about 0% an?larger reduction for stainless steel coupons owing to lower print quality.?Ductility more sensitive.

Ductility of as-built material - coupons before and after?loading

Fatigue behaviour of WAAM carbon steel

High-cycle fatigue testing performed on θ= 90°?machined and as-built coupons performed, covering various stress ranges and stress ratios (R = min/0.1, 0.2, 0.3 and 0.4).

Comparisons with steel butt welds and S355 structural steel

Fatigue crack growth (FCG) behaviour of WAAM steels

FCG tests on machined?compact tension (CT) specimens were conducted, extracted at different directions?to the print layer orientation (θ = 0°, 45° and 90°).

Analysis of geometry

Scan data used to determine volume, mean cross-sectional area, variation in thickness etc

Comparison with AISC 370 provisions

When weakening effect of geometric undulations is included in material properties (i.e. provided as-built 'effective' material properties are used), local buckling behaviour of 3D printed stub columns similar to that of conventional sections and well predicted by existing design provisions

Column buckling

Comparison with code predictions for columns