Experimental Mechanics最新文献_第9页

A Modified Losipescu Method for Evaluating In-Situ Shear Behavior Using High-Temperature X-Ray Computed Tomography 一种改进的Losipescu方法在高温x射线计算机断层扫描中评价原位剪切行为

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-26 DOI: 10.1007/s11340-025-01163-4

W. Lu, X. Li, W. Du, R. Huang, Y. Chen, Z. Qu

Background

Ceramic matrix composites (CMCs) are widely used in high-temperature environments, and due to their low shear strength, failure is primarily governed by shear performance. It is imperative to reveal their shear failure mechanism in-situ under high-temperature conditions.

Objective

The in-situ shear test of CMCs under high-temperature conditions was realized through the improved Iosipescu method.

Methods

Based on the traditional Iosipescu method, this study proposes an improved small-scale Iosipescu method with fewer parts and without threaded fastening parts. Furthermore, this method can be applied to high-temperature in-situ loading.

Results

The specimen's stress field and failure mode were obtained via numerical simulation under the improved Iosipescu method. The in-plane shear strength (IPSS) of the 2D-C/SiC composites from room temperature (RT) to 1100 °C was tested under atmospheric conditions using the improved Iosipescu method. The results showed that the IPSS of the 2D-C/SiC composites increased as the temperature rose to 900 °C and then decreased as the temperature continued to rise. Furthermore, the in-situ shear test of 2D-C/SiC composite materials at 900 °C was performed using the improved Iosipescu method. From the analysis of the tomographic images, it can be seen that the specimen had void defects before the load was applied, and as the load increased, composite material damage began to develop along the original defects until the specimen broke and failed. SEM observed the fracture surface of the sample, and the failure modes at different temperatures were obtained, explaining why IPSS changes with temperature.

Conclusions

The improved Iosipescu method is used to measure the high-temperature in-plane shear properties of CMCs and can enable high-temperature in-situ testing.

陶瓷基复合材料（cmc）广泛应用于高温环境中，由于其抗剪强度低，其破坏主要受剪切性能的影响。在高温条件下原位揭示其剪切破坏机制势在必行。目的采用改进的Iosipescu法实现高温条件下cmc的原位剪切试验。方法在传统Iosipescu方法的基础上，提出了一种零件较少、不需要螺纹紧固零件的改进小型Iosipescu方法。此外，该方法可应用于高温原位加载。结果采用改进的Iosipescu方法进行数值模拟，得到了试件的应力场和破坏模式。采用改进的Iosipescu法，在常压条件下测试了2D-C/SiC复合材料在室温~ 1100℃的面内剪切强度（IPSS）。结果表明：当温度升高至900℃时，2D-C/SiC复合材料的IPSS增大，随后随着温度的升高而减小；此外，采用改进的Iosipescu方法对2D-C/SiC复合材料进行了900℃的原位剪切试验。从层析图像分析可以看出，试样在加载前就存在空洞缺陷，随着载荷的增大，复合材料损伤开始沿原缺陷发展，直至试样破裂失效。SEM观察了试样的断裂面，得到了不同温度下的破坏模式，解释了IPSS随温度变化的原因。结论改进的Iosipescu方法可用于测量cmc的高温面内剪切性能，并可进行高温原位测试。

{"title":"A Modified Losipescu Method for Evaluating In-Situ Shear Behavior Using High-Temperature X-Ray Computed Tomography","authors":"W. Lu, X. Li, W. Du, R. Huang, Y. Chen, Z. Qu","doi":"10.1007/s11340-025-01163-4","DOIUrl":"10.1007/s11340-025-01163-4","url":null,"abstract":"<div><h3>Background</h3><p>Ceramic matrix composites (CMCs) are widely used in high-temperature environments, and due to their low shear strength, failure is primarily governed by shear performance. It is imperative to reveal their shear failure mechanism in-situ under high-temperature conditions.</p><h3>Objective</h3><p>The in-situ shear test of CMCs under high-temperature conditions was realized through the improved Iosipescu method.</p><h3>Methods</h3><p>Based on the traditional Iosipescu method, this study proposes an improved small-scale Iosipescu method with fewer parts and without threaded fastening parts. Furthermore, this method can be applied to high-temperature in-situ loading.</p><h3>Results</h3><p>The specimen's stress field and failure mode were obtained via numerical simulation under the improved Iosipescu method. The in-plane shear strength (IPSS) of the 2D-C/SiC composites from room temperature (RT) to 1100 °C was tested under atmospheric conditions using the improved Iosipescu method. The results showed that the IPSS of the 2D-C/SiC composites increased as the temperature rose to 900 °C and then decreased as the temperature continued to rise. Furthermore, the in-situ shear test of 2D-C/SiC composite materials at 900 °C was performed using the improved Iosipescu method. From the analysis of the tomographic images, it can be seen that the specimen had void defects before the load was applied, and as the load increased, composite material damage began to develop along the original defects until the specimen broke and failed. SEM observed the fracture surface of the sample, and the failure modes at different temperatures were obtained, explaining why IPSS changes with temperature.</p><h3>Conclusions</h3><p>The improved Iosipescu method is used to measure the high-temperature in-plane shear properties of CMCs and can enable high-temperature in-situ testing.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"683 - 697"},"PeriodicalIF":2.0,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144074126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Plasticity Bridges Microscale Martensitic Shear Bands in Superelastic Nitinol 超弹性镍钛诺中的塑性桥接微尺度马氏体剪切带

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-26 DOI: 10.1007/s11340-025-01161-6

A. Christison, H. M. Paranjape, S. Daly

Background

Superelastic shape memory alloys (SMAs) such as nickel-titanium, also known as Nitinol, recover large deformations via a reversible, stress-induced martensitic transformation.

Objective

Partitioning the deformation into the contributions from superelasticity and plasticity and quantifying the interaction between these mechanisms is key to modeling their fatigue behavior.

Methods

We capture these microscopic interactions across many grains using a combination of scanning electron microscopy digital image correlation (SEM-DIC) and electron backscatter diffraction (EBSD). Modeling our data as a statistical distribution, we employ a Gaussian Mixture Model (GMM) soft clustering framework to understand how these mechanisms interact and evolve as a function of global strain.

Results

Our findings show that, under globally-applied uniaxial tensile loading, plasticity bridges deformation in regions where competing positive and negative martensitic shear bands intersect. Early stage transformation-induced plasticity is concentrated at these intersections and forms concurrently with the Lüders-like martensitic transformation front, often appearing with a zig-zag pattern that is linked to compound twinning at the martensite-martensite interface. At higher strains, austenite slip is activated as a second mechanism of plastic deformation.

Conclusions

We propose that this plastic bridging mechanism underpins the prestrain effects previously reported in the literature, where higher prestrains can enhance the fatigue strength of superelastic materials within a given loading mode.

超弹性形状记忆合金（sma），如镍钛，也称为镍钛诺，通过可逆的应力诱导马氏体相变恢复大变形。目的将变形划分为超弹性和塑性两种机制的贡献，并量化这两种机制之间的相互作用是建立其疲劳行为模型的关键。方法我们利用扫描电子显微镜数字图像相关（SEM-DIC）和电子背散射衍射（EBSD）的组合来捕捉这些微观相互作用。我们将数据建模为统计分布，采用高斯混合模型（GMM）软聚类框架来理解这些机制如何作为全球应变的函数相互作用和演变。结果表明，在全球范围内施加的单轴拉伸载荷下，塑性桥梁在竞争的正、负马氏体剪切带相交的区域发生变形。早期相变诱导的塑性集中在这些交叉点，并与l德氏体相变前沿同时形成，经常以锯齿形图案出现，与马氏体-马氏体界面的复合孪晶有关。在较高应变下，奥氏体滑移作为塑性变形的第二种机制被激活。我们提出，这种塑性桥接机制支持先前文献中报道的预应变效应，其中较高的预应变可以提高超弹性材料在给定加载模式下的疲劳强度。

{"title":"Plasticity Bridges Microscale Martensitic Shear Bands in Superelastic Nitinol","authors":"A. Christison, H. M. Paranjape, S. Daly","doi":"10.1007/s11340-025-01161-6","DOIUrl":"10.1007/s11340-025-01161-6","url":null,"abstract":"<div><h3>Background</h3><p>Superelastic shape memory alloys (SMAs) such as nickel-titanium, also known as Nitinol, recover large deformations via a reversible, stress-induced martensitic transformation.</p><h3>Objective</h3><p>Partitioning the deformation into the contributions from superelasticity and plasticity and quantifying the interaction between these mechanisms is key to modeling their fatigue behavior.</p><h3>Methods</h3><p>We capture these microscopic interactions across many grains using a combination of scanning electron microscopy digital image correlation (SEM-DIC) and electron backscatter diffraction (EBSD). Modeling our data as a statistical distribution, we employ a Gaussian Mixture Model (GMM) soft clustering framework to understand how these mechanisms interact and evolve as a function of global strain.</p><h3>Results</h3><p>Our findings show that, under globally-applied uniaxial tensile loading, plasticity bridges deformation in regions where competing positive and negative martensitic shear bands intersect. Early stage transformation-induced plasticity is concentrated at these intersections and forms concurrently with the Lüders-like martensitic transformation front, often appearing with a zig-zag pattern that is linked to compound twinning at the martensite-martensite interface. At higher strains, austenite slip is activated as a second mechanism of plastic deformation.</p><h3>Conclusions</h3><p>We propose that this plastic bridging mechanism underpins the prestrain effects previously reported in the literature, where higher prestrains can enhance the fatigue strength of superelastic materials within a given loading mode.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"699 - 716"},"PeriodicalIF":2.0,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-025-01161-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144074125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the Cover: An Internal Digital Image Correlation Technique for High-Strain Rate Dynamic Experiments 封面：用于高应变速率动态实验的内部数字图像相关技术

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-26 DOI: 10.1007/s11340-025-01162-5

引用次数: 0

Dynamic Mechanical Behavior of Sinusoidal Corrugated Dual-Phase Lattice Metamaterials by Additive Manufacturing 增材制造正弦波纹双相晶格超材料的动态力学行为

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-20 DOI: 10.1007/s11340-025-01160-7

H. Wang, J. You, Y. Tian, Z. Chen, S. Yin

Background

Additive manufacturing enables lattice metamaterials designed with complex architectures. However, how to design the architecture for greater impact resistance remains not fully explored.

Objective

This study aims to develop bio-inspired dual-phase metamaterials and examine their dynamic performance.

Methods

By mimicking the impact region of mantis shrimp, dual-phase lattices (DPLs) were designed by incorporating reinforcement phase (RP) as sinusoidal corrugated forms with multiple phase differences. Then, those metamaterial composites were fabricated using additive manufacturing techniques with stainless steel powder and compressed under different strain rates.

Results

Under quasi-static compression conditions, DPLs demonstrated superior energy absorption capacity compared to traditional homogeneous lattice materials. For DPLs with various phase architectures, the differences in load-bearing capacity, failure modes, and impact energy dissipation time became more pronounced as strain rate increased. The dual-phase lattice metamaterials showed 2.83 times greater strength values under low-speed impact conditions than those under quasi-static compression, demonstrating excellent strain-rate hardening effects. Failure modes were found to be associated with both RP arrangement patterns and compressive strain rates. However, the shear band propagation paths under low-speed impact were consistent with those observed under quasi-static compression, indicating that RP pattern governed the shear band distribution irrespective of impact velocity.

Conclusions

This work provided valuable insights for the architecture design of lattice metamaterials in dynamic application.

增材制造使晶格超材料设计具有复杂的结构。然而，如何设计具有更大抗冲击性的结构仍未得到充分探索。目的研制仿生双相超材料，并对其动态性能进行研究。方法模拟螳螂虾的冲击区域，将增强相（RP）作为多相位差的正弦波形，设计双相晶格（dpl）。然后，采用增材制造技术，以不锈钢粉为原料，在不同应变速率下进行压缩，制备出这些超材料复合材料。结果在准静态压缩条件下，与传统的均匀晶格材料相比，DPLs具有更好的能量吸收能力。对于不同相结构的DPLs，随着应变率的增加，承载能力、破坏模式和冲击耗能时间的差异更加明显。双相晶格超材料在低速冲击条件下的强度值是准静态压缩条件下的2.83倍，表现出优异的应变速率硬化效果。发现破坏模式与RP排列模式和压缩应变率有关。然而，低速冲击下剪切带的传播路径与准静态压缩下剪切带的传播路径一致，表明无论冲击速度如何，剪切带的分布都以RP模式为主。结论本研究为晶格超材料在动态应用中的结构设计提供了有价值的见解。

{"title":"Dynamic Mechanical Behavior of Sinusoidal Corrugated Dual-Phase Lattice Metamaterials by Additive Manufacturing","authors":"H. Wang, J. You, Y. Tian, Z. Chen, S. Yin","doi":"10.1007/s11340-025-01160-7","DOIUrl":"10.1007/s11340-025-01160-7","url":null,"abstract":"<div><h3>Background</h3><p>Additive manufacturing enables lattice metamaterials designed with complex architectures. However, how to design the architecture for greater impact resistance remains not fully explored.</p><h3>Objective</h3><p>This study aims to develop bio-inspired dual-phase metamaterials and examine their dynamic performance.</p><h3>Methods</h3><p>By mimicking the impact region of mantis shrimp, dual-phase lattices (DPLs) were designed by incorporating reinforcement phase (RP) as sinusoidal corrugated forms with multiple phase differences. Then, those metamaterial composites were fabricated using additive manufacturing techniques with stainless steel powder and compressed under different strain rates.</p><h3>Results</h3><p>Under quasi-static compression conditions, DPLs demonstrated superior energy absorption capacity compared to traditional homogeneous lattice materials. For DPLs with various phase architectures, the differences in load-bearing capacity, failure modes, and impact energy dissipation time became more pronounced as strain rate increased. The dual-phase lattice metamaterials showed 2.83 times greater strength values under low-speed impact conditions than those under quasi-static compression, demonstrating excellent strain-rate hardening effects. Failure modes were found to be associated with both RP arrangement patterns and compressive strain rates. However, the shear band propagation paths under low-speed impact were consistent with those observed under quasi-static compression, indicating that RP pattern governed the shear band distribution irrespective of impact velocity.</p><h3>Conclusions</h3><p>This work provided valuable insights for the architecture design of lattice metamaterials in dynamic application.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 4","pages":"541 - 551"},"PeriodicalIF":2.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143918963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development of Kolsky Tension Bar Based Dynamic Incremental Strain and Singular Strain Loading Capability 基于动态增量应变和奇异应变加载能力的Kolsky拉力杆的发展

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-19 DOI: 10.1007/s11340-025-01159-0

B. Song, T. Martinez, A. Y. Ku, J. Deitz, P. Noell

Background

The multiple loadings in a conventional Kolsky bar test prevent an in-depth understanding of the relationship between microstructure change and load history under dynamic loading.

Objective

In order to correlate the microstructural changes to the dynamic load history, it is necessary to develop a new dynamic test capability that allows the specimen be incrementally deformed with a singular loading for each strain increment.

Methods

A dynamic incremental strain and singular strain loading (DI (epsilon) SϵL) capability based on Kolsky tension bar technique was developed. Different design options and considerations are presented to facilitate the DI (epsilon) SϵL capability such that the user can choose the combination that best meets their test requirements.

Results

To demonstrate the new capability, a dog-bone shaped 316L stainless steel was subjected to a series of dynamic tensile loadings with an incremental strain of ~ 11% for each singular loading test. The 316L stainless steel specimens were subjected to a singular loading but different strains under adiabatic condition. At the same dynamic strain rate, the 316L stainless steel became softer and less ductile under adiabatic condition due to adiabatic heating.

Conclusions

With this new capability, one could decouple the thermosoftening from a conventional dynamic tension test for predictive rate-dependent material model development. The information obtained from this capability may also be used to determine microstructural change and/or damage evolution during dynamic tension testing.

传统的科尔斯基杆试验中的多次加载阻碍了对动态加载下微观结构变化与加载历史之间关系的深入理解。目的为了将微观结构变化与动载荷历史联系起来，有必要开发一种新的动态试验能力，允许试样在每次应变增量的单一载荷下进行增量变形。方法开发基于Kolsky张力杆技术的动态增量应变和奇异应变加载（DI (epsilon) SϵL）能力。提出了不同的设计选项和考虑因素，以促进DI (epsilon) SϵL功能，以便用户可以选择最能满足其测试要求的组合。结果为了证明这种新能力，狗骨型316L不锈钢承受了一系列增量应变为11的动态拉伸载荷% for each singular loading test. The 316L stainless steel specimens were subjected to a singular loading but different strains under adiabatic condition. At the same dynamic strain rate, the 316L stainless steel became softer and less ductile under adiabatic condition due to adiabatic heating.ConclusionsWith this new capability, one could decouple the thermosoftening from a conventional dynamic tension test for predictive rate-dependent material model development. The information obtained from this capability may also be used to determine microstructural change and/or damage evolution during dynamic tension testing.

{"title":"Development of Kolsky Tension Bar Based Dynamic Incremental Strain and Singular Strain Loading Capability","authors":"B. Song, T. Martinez, A. Y. Ku, J. Deitz, P. Noell","doi":"10.1007/s11340-025-01159-0","DOIUrl":"10.1007/s11340-025-01159-0","url":null,"abstract":"<div><h3>Background</h3><p>The multiple loadings in a conventional Kolsky bar test prevent an in-depth understanding of the relationship between microstructure change and load history under dynamic loading.</p><h3>Objective</h3><p>In order to correlate the microstructural changes to the dynamic load history, it is necessary to develop a new dynamic test capability that allows the specimen be incrementally deformed with a singular loading for each strain increment.</p><h3>Methods</h3><p>A dynamic incremental strain and singular strain loading (DI <span>(epsilon)</span> S<i>ϵ</i>L) capability based on Kolsky tension bar technique was developed. Different design options and considerations are presented to facilitate the DI <span>(epsilon)</span> S<i>ϵ</i>L capability such that the user can choose the combination that best meets their test requirements.</p><h3>Results</h3><p>To demonstrate the new capability, a dog-bone shaped 316L stainless steel was subjected to a series of dynamic tensile loadings with an incremental strain of ~ 11% for each singular loading test. The 316L stainless steel specimens were subjected to a singular loading but different strains under adiabatic condition. At the same dynamic strain rate, the 316L stainless steel became softer and less ductile under adiabatic condition due to adiabatic heating.</p><h3>Conclusions</h3><p>With this new capability, one could decouple the thermosoftening from a conventional dynamic tension test for predictive rate-dependent material model development. The information obtained from this capability may also be used to determine microstructural change and/or damage evolution during dynamic tension testing.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"667 - 681"},"PeriodicalIF":2.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144073738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Understanding the Incident Wave Errors in Split Hopkinson Pressure Bar Test with Machine Learning Method 用机器学习方法分析Hopkinson压杆劈裂试验中入射波误差

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-18 DOI: 10.1007/s11340-025-01146-5

K. Wang, Y. Wu, X. Zhou, Y. Yu, L. Xu, G. Gao

Background

In Split Hopkinson Pressure Bar (SHPB) test, the misalignment of the striker bar leads to waveform errors in the incident wave, which results in inaccurate material mechanical property parameters.

Objective

The goal of this paper is to apply machine learning (ML) method to understand waveform errors in incident waves (error peak-valley features) and investigate the impact of imperfect striker bar on the incident wave.

Methods

ML projects were constructed by developing numerical models to establish waveform databases based on experimental data, and the continuous optimization of ML projects advances the application of a dual-output average curve (DOAC) method simulating the use of two strain gauges for error processing.

Results

The waveform errors were categorized into two types: non-parallel impact and parallel non-coaxial impact by continuously optimizing the ML model through error analysis, successfully understanding up to 24 types of waveforms. DOAC effectively eliminated the bending effect, and the error effects were decomposed into bending effects and other effects.

Conclusion

The high-accuracy ML results provide simple and real-time automatic correction solutions for waveform errors and quantify the errors, closing the loop between numerical simulation and experiments. The error and dispersion coupling effects can be successfully decoupled using DOAC, suggesting that bending waves are the main cause of error effects with the dominant bending effects.

在分离式霍普金森压杆（SHPB）试验中，冲击杆的不对准会导致入射波的波形误差，从而导致材料力学性能参数的不准确。目的应用机器学习（ML）方法了解入射波中的波形误差（误差峰谷特征），并研究不完善的冲击杆对入射波的影响。方法以实验数据为基础，建立数值模型建立波形数据库，通过对ML项目的不断优化，促进了双输出平均曲线法（DOAC）的应用，该方法模拟使用两个应变片进行误差处理。结果通过误差分析不断优化ML模型，将波形误差分为非平行冲击和平行非同轴冲击两种类型，成功理解了多达24种波形。DOAC有效地消除了弯曲效应，并将误差效应分解为弯曲效应和其他效应。结论高精度的ML结果为波形误差提供了简单、实时的自动校正方案，实现了误差的量化，完成了数值模拟与实验之间的闭环。使用DOAC可以成功地解耦误差和色散耦合效应，表明弯曲波是误差效应的主要原因，弯曲效应占主导地位。

{"title":"Understanding the Incident Wave Errors in Split Hopkinson Pressure Bar Test with Machine Learning Method","authors":"K. Wang, Y. Wu, X. Zhou, Y. Yu, L. Xu, G. Gao","doi":"10.1007/s11340-025-01146-5","DOIUrl":"10.1007/s11340-025-01146-5","url":null,"abstract":"<div><h3>Background</h3><p>In Split Hopkinson Pressure Bar (SHPB) test, the misalignment of the striker bar leads to waveform errors in the incident wave, which results in inaccurate material mechanical property parameters.</p><h3>Objective</h3><p>The goal of this paper is to apply machine learning (ML) method to understand waveform errors in incident waves (error peak-valley features) and investigate the impact of imperfect striker bar on the incident wave.</p><h3>Methods</h3><p>ML projects were constructed by developing numerical models to establish waveform databases based on experimental data, and the continuous optimization of ML projects advances the application of a dual-output average curve (DOAC) method simulating the use of two strain gauges for error processing.</p><h3>Results</h3><p>The waveform errors were categorized into two types: non-parallel impact and parallel non-coaxial impact by continuously optimizing the ML model through error analysis, successfully understanding up to 24 types of waveforms. DOAC effectively eliminated the bending effect, and the error effects were decomposed into bending effects and other effects.</p><h3>Conclusion</h3><p>The high-accuracy ML results provide simple and real-time automatic correction solutions for waveform errors and quantify the errors, closing the loop between numerical simulation and experiments. The error and dispersion coupling effects can be successfully decoupled using DOAC, suggesting that bending waves are the main cause of error effects with the dominant bending effects.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 2","pages":"283 - 303"},"PeriodicalIF":2.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Performance Analysis of Digital Camera in DIC: Physical Parameters, Noise, and Bit-Depths 数码相机在DIC中的性能分析：物理参数、噪声和位深

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-15 DOI: 10.1007/s11340-025-01157-2

A. Haghighi, N. Soltani, H. Asemani

Background

The accuracy of Digital Image Correlation is considerably influenced by the quality of images taken from the specimen surface. While previous have examined the impact of camera parameters on DIC results, the relationship between camera characteristics and DIC errors remains unclear.

Objective

In this study, a new theoretical model is introduced to estimate the DIC errors sourced from the camera.

Methods

The model is derived from the EMVA 1288 standard and contains camera gain, bit depth, and noise error. To validate the model, its results were compared with the real errors calculated from DIC results, and to determine the accurate error, various noise and gains effects were applied to digital images and then displacement and strain were numerically applied to these manipulated images and original images. The error calculated from the DIC successfully matched the error estimated by the model, proving the applicability of the models.

Results

The individual effects of noise, camera gain, and bit depth are analyzed separately, exploring their respective influences on the DIC. Subsequently, a simple formula is proposed to express camera performance in DIC.

Conclusions

Results showed that the DIC accuracy is considerably influenced by the camera gain, and temporal dark noise has a notable impact on DIC accuracy, particularly in scenarios with low-contrast speckle patterns. However, the influence of bit depth is negligible.

数字图像相关的精度很大程度上受到试样表面图像质量的影响。虽然之前已经研究了相机参数对DIC结果的影响，但相机特性与DIC误差之间的关系尚不清楚。目的引入一种新的理论模型来估计来自相机的DIC误差。方法该模型基于EMVA 1288标准，包含摄像机增益、位元深度和噪声误差。为了验证模型，将其结果与DIC结果计算的实际误差进行了比较，并对数字图像施加了各种噪声和增益效应，然后对这些处理图像和原始图像进行了位移和应变数值计算，以确定准确的误差。由DIC计算的误差与模型估计的误差成功匹配，证明了模型的适用性。结果分别分析了噪声、相机增益和比特深度的单独影响，探讨了它们各自对DIC的影响。随后，提出了一个简单的公式来表达相机在DIC中的性能。结果表明，DIC精度受相机增益的影响较大，而时间暗噪声对DIC精度有显著影响，特别是在低对比度散斑模式下。然而，比特深度的影响可以忽略不计。

{"title":"Performance Analysis of Digital Camera in DIC: Physical Parameters, Noise, and Bit-Depths","authors":"A. Haghighi, N. Soltani, H. Asemani","doi":"10.1007/s11340-025-01157-2","DOIUrl":"10.1007/s11340-025-01157-2","url":null,"abstract":"<div><h3>Background</h3><p>The accuracy of Digital Image Correlation is considerably influenced by the quality of images taken from the specimen surface. While previous have examined the impact of camera parameters on DIC results, the relationship between camera characteristics and DIC errors remains unclear.</p><h3>Objective</h3><p>In this study, a new theoretical model is introduced to estimate the DIC errors sourced from the camera.</p><h3>Methods</h3><p>The model is derived from the EMVA 1288 standard and contains camera gain, bit depth, and noise error. To validate the model, its results were compared with the real errors calculated from DIC results, and to determine the accurate error, various noise and gains effects were applied to digital images and then displacement and strain were numerically applied to these manipulated images and original images. The error calculated from the DIC successfully matched the error estimated by the model, proving the applicability of the models.</p><h3>Results</h3><p>The individual effects of noise, camera gain, and bit depth are analyzed separately, exploring their respective influences on the DIC. Subsequently, a simple formula is proposed to express camera performance in DIC.</p><h3>Conclusions</h3><p>Results showed that the DIC accuracy is considerably influenced by the camera gain, and temporal dark noise has a notable impact on DIC accuracy, particularly in scenarios with low-contrast speckle patterns. However, the influence of bit depth is negligible.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"653 - 666"},"PeriodicalIF":2.0,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144073923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Shape Function-Based Strain Determination in DIC for Solids and Lattice Structures 基于形状函数的固体和晶格结构DIC应变测定

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-12 DOI: 10.1007/s11340-025-01155-4

M. Hofmann, M. Greiner, M. Klein, M. Oechsner, C. Mittelstedt

Background

Additive Manufacturing offers the opportunity to build lattice structures with benefits in manufacturing efficiency and weight. For the determination of the fatigue properties of lattice structures, it lacks a method to determine the deformation under mechanic stress.

Objective

A digital image correlation (DIC) algorithm was implemented. The algorithm determines strains within a subset in an uncommon way by physically interpreting the subset shape function and does not need neighboring subsets, therefore.

Method

With a monochrome background this shape function-based strain determination is able to determine the deformation of a whole lattice unit cell, even if the background is visible in sectors of the subset. The implementation is validated by comparing the results in quasi-static tests on bulk material specimens to the results tactile sensors and a conventional DIC program. Then the deformation of lattice unit cells in fatigue tests is evaluated.

Results

The shape function-based strain determination performs well in quasi-static tests even for large deformations. The deformation of lattice unit cells is determined successfully, whereby conventional DIC algorithms can be challenged if the lattice’s strut diameter becomes close to the image resolution. The determined strains are appropriate for lifetime prediction and fractures can be detected.

Conclusion

The shape function-based strain determination is a suitable tool for determination of large local strains as well as strains in lattice structures, which do partially not cover the background in the whole region of interest due to periodic empty spaces between the lattice struts. For determination of strain fields, conventional DIC algorithms will still be more efficient in this state of development.

增材制造提供了构建晶格结构的机会，在制造效率和重量方面都有好处。在确定晶格结构的疲劳性能时，缺乏一种确定其在机械应力作用下变形的方法。目的实现一种数字图像相关（DIC）算法。该算法通过物理解释子集形状函数，以一种罕见的方式确定子集内的应变，因此不需要邻近的子集。方法在单色背景下，这种基于形状函数的应变测定能够确定整个晶格单元格的变形，即使背景在子集的扇区中可见。通过将块状材料试样的准静态测试结果与触觉传感器和传统DIC程序的测试结果进行比较，验证了该方法的有效性。然后对晶格单元格在疲劳试验中的变形进行了评价。结果基于形状函数的应变测定方法即使在大变形的准静态试验中也具有良好的性能。成功地确定了晶格单元格的变形，从而挑战了传统的DIC算法，当晶格的支柱直径接近图像分辨率时。所确定的应变适合于寿命预测，并且可以检测到断裂。结论基于形状函数的应变测定方法适用于大局部应变和晶格结构应变的测定，晶格结构由于晶格杆之间存在周期性的空白空间，不能部分覆盖整个目标区域的背景。对于应变场的确定，在这种发展状态下，传统的DIC算法仍然是更有效的。

{"title":"Shape Function-Based Strain Determination in DIC for Solids and Lattice Structures","authors":"M. Hofmann, M. Greiner, M. Klein, M. Oechsner, C. Mittelstedt","doi":"10.1007/s11340-025-01155-4","DOIUrl":"10.1007/s11340-025-01155-4","url":null,"abstract":"<div><h3>Background</h3><p>Additive Manufacturing offers the opportunity to build lattice structures with benefits in manufacturing efficiency and weight. For the determination of the fatigue properties of lattice structures, it lacks a method to determine the deformation under mechanic stress.</p><h3>Objective</h3><p>A digital image correlation (DIC) algorithm was implemented. The algorithm determines strains within a subset in an uncommon way by physically interpreting the subset shape function and does not need neighboring subsets, therefore.</p><h3>Method</h3><p>With a monochrome background this shape function-based strain determination is able to determine the deformation of a whole lattice unit cell, even if the background is visible in sectors of the subset. The implementation is validated by comparing the results in quasi-static tests on bulk material specimens to the results tactile sensors and a conventional DIC program. Then the deformation of lattice unit cells in fatigue tests is evaluated.</p><h3>Results</h3><p>The shape function-based strain determination performs well in quasi-static tests even for large deformations. The deformation of lattice unit cells is determined successfully, whereby conventional DIC algorithms can be challenged if the lattice’s strut diameter becomes close to the image resolution. The determined strains are appropriate for lifetime prediction and fractures can be detected.</p><h3>Conclusion</h3><p>The shape function-based strain determination is a suitable tool for determination of large local strains as well as strains in lattice structures, which do partially not cover the background in the whole region of interest due to periodic empty spaces between the lattice struts. For determination of strain fields, conventional DIC algorithms will still be more efficient in this state of development.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"637 - 652"},"PeriodicalIF":2.0,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-025-01155-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144073587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development of a New Pure Bending Tester for Small-Scale Specimens 小型试件纯弯曲试验机的研制

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-11 DOI: 10.1007/s11340-025-01154-5

L. Zhang, J. Hu, H. Liu, D. Liu

Background

The characterization of the moment–curvature relationship for thin components within the elastic–plastic regime yields crucial insights not readily ascertainable through conventional tensile testing. However, most conventional bending testers only measure the force–displacement data of specimens without providing the bending moment and curvature information directly.

Objective

We aim to develop a pure-bending tester based on the cochleoid theory that can directly measure the bending moment–curvature response of thin components.

Methods

The bending moment is determined by employing a flexural pivot with a known spring constant paired with dual laser displacement sensors. By approximating the cochleoid as an eccentric arc trajectory, we move and rotate one end of the specimen to increase the curvature gradually. Finally, the moment–curvature relationship of the specimens can be obtained.

Results

The practical capability of the bending tester is demonstrated by measuring moment–curvature data from various specimens, including PET sheets, aluminum sheets, and Nylon 6 monofilaments. Cyclic bending and relaxation tests are performed on these typical specimens. The measurement results agree well with the theoretical predictions.

Conclusions

The instrument serves as a valuable tool for characterizing the bending properties of diverse small-scale components. Its versatility facilitates comprehensive assessments of the bending behavior of various materials and structures.

在弹塑性状态下薄构件的力矩-曲率关系的表征产生了通过常规拉伸试验不易确定的关键见解。然而，大多数传统的弯曲试验机只测量试件的力-位移数据，而不直接提供弯矩和曲率信息。目的研制一种基于耳蜗理论的纯弯曲测试仪，可直接测量薄构件的弯矩曲率响应。方法采用已知弹簧常数的弯曲枢轴与双激光位移传感器配对来确定弯矩。通过将耳蜗近似为偏心弧形轨迹，我们移动和旋转标本的一端以逐渐增加曲率。最后，得到了试件的弯矩-曲率关系。结果通过测量PET片材、铝片材和尼龙6单丝的弯矩-曲率数据，证明了弯曲测试仪的实用性。对这些典型试件进行了循环弯曲和松弛试验。测量结果与理论预测吻合较好。结论该仪器可作为一种有价值的工具来表征各种小尺寸构件的弯曲特性。它的多功能性有助于对各种材料和结构的弯曲性能进行全面评估。

{"title":"Development of a New Pure Bending Tester for Small-Scale Specimens","authors":"L. Zhang, J. Hu, H. Liu, D. Liu","doi":"10.1007/s11340-025-01154-5","DOIUrl":"10.1007/s11340-025-01154-5","url":null,"abstract":"<div><h3>Background</h3><p>The characterization of the moment–curvature relationship for thin components within the elastic–plastic regime yields crucial insights not readily ascertainable through conventional tensile testing. However, most conventional bending testers only measure the force–displacement data of specimens without providing the bending moment and curvature information directly.</p><h3>Objective</h3><p>We aim to develop a pure-bending tester based on the cochleoid theory that can directly measure the bending moment–curvature response of thin components.</p><h3>Methods</h3><p>The bending moment is determined by employing a flexural pivot with a known spring constant paired with dual laser displacement sensors. By approximating the cochleoid as an eccentric arc trajectory, we move and rotate one end of the specimen to increase the curvature gradually. Finally, the moment–curvature relationship of the specimens can be obtained.</p><h3>Results</h3><p>The practical capability of the bending tester is demonstrated by measuring moment–curvature data from various specimens, including PET sheets, aluminum sheets, and Nylon 6 monofilaments. Cyclic bending and relaxation tests are performed on these typical specimens. The measurement results agree well with the theoretical predictions.</p><h3>Conclusions</h3><p>The instrument serves as a valuable tool for characterizing the bending properties of diverse small-scale components. Its versatility facilitates comprehensive assessments of the bending behavior of various materials and structures.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"625 - 636"},"PeriodicalIF":2.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144073682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

An Experimental Method for Fatigue Testing Cast Iron Water Pipes Using Combined Internal Water Pressure and Bending Loads 铸铁水管内水压与弯曲载荷联合疲劳试验方法研究

IF 2 3区工程技术 Q2 MATERIALS SCIENCE, CHARACTERIZATION & TESTING

Experimental Mechanics

Pub Date : 2025-02-10 DOI: 10.1007/s11340-025-01153-6

E. D. A. John, J. B. Boxall, R. P. Collins, E. T. Bowman, L. Susmel

Background

Investigations into the fatigue failures mechanism of Grey Cast Iron (GCI) water pipes are inhibited by the lack of a lab-based method to conduct extensive high-cycle biaxial fatigue test programmes.

Objective

The work presented in this paper developed and tested a novel experiment capable of causing controlled fatigue failures of GCI pipe specimens in the high-cycle fatigue regime using bending and internal water pressure fatigue loading.

Methods

A novel four-point bending and internal water pressure fatigue testing system was developed to apply constant amplitude out-of-phase biaxial loading to 58 mm diameter GCI pipes at 1.7 Hz. To verify the ability of this equipment to apply known stresses and repeatable loads to pipe specimens a series of tests were conducted. A finite element model of the pipe specimen was used to estimate the strains and displacements applied by the equipment.

Results

Experimental strains and displacements were mainly within ± 10% of the estimated values and the pressure amplitudes measured over 10³ cycles were within ± 3% of the average. Dynamic load effects occurred at higher bending loads, but these were quantified and accounted for. Trial destructive tests revealed that the lifespan of leaking fatigue cracks in GCI pipes with uniform wall-loss subject to combined internal pressure and bending fatigue loads is less than 1% of the total cycles-to-burst.

Conclusions

The experimental method developed was able to apply combined, out-of-phase internal pressure and bending fatigue loads accurately and consistently to small-dimeter GCI pipes, and cause these pipes to develop high-cycle fatigue regime failures.

灰口铸铁（GCI）水管疲劳失效机理的研究由于缺乏基于实验室的方法进行广泛的高周双轴疲劳试验而受到抑制。目的开发并测试了一种新的实验方法，该实验能够在弯曲和内水压疲劳加载的情况下引起GCI管试件在高周疲劳状态下的可控疲劳失效。方法研制了一种新颖的四点弯曲和内水压疲劳试验系统，对直径为58 mm的GCI管施加1.7 Hz的恒幅异相双轴加载。为了验证该设备对管道样品施加已知应力和可重复载荷的能力，进行了一系列测试。利用管道试样的有限元模型来估计设备施加的应变和位移。结果实验应变和位移主要在估计值的±10%以内，103个周期内测得的压力幅值在平均值的±3%以内。动载荷效应发生在较高的弯曲载荷下，但这些都是量化的。破坏试验表明，均匀壁损的GCI管道在内压和弯曲疲劳载荷联合作用下，泄漏疲劳裂纹的寿命小于总循环爆裂周期的1%。结论该实验方法能够准确、一致地对小口径GCI管道施加异相内压和弯曲疲劳载荷，使管道发生高周疲劳失效。

{"title":"An Experimental Method for Fatigue Testing Cast Iron Water Pipes Using Combined Internal Water Pressure and Bending Loads","authors":"E. D. A. John, J. B. Boxall, R. P. Collins, E. T. Bowman, L. Susmel","doi":"10.1007/s11340-025-01153-6","DOIUrl":"10.1007/s11340-025-01153-6","url":null,"abstract":"<div><h3>Background</h3><p>Investigations into the fatigue failures mechanism of Grey Cast Iron (GCI) water pipes are inhibited by the lack of a lab-based method to conduct extensive high-cycle biaxial fatigue test programmes.</p><h3>Objective</h3><p>The work presented in this paper developed and tested a novel experiment capable of causing controlled fatigue failures of GCI pipe specimens in the high-cycle fatigue regime using bending and internal water pressure fatigue loading.</p><h3>Methods</h3><p>A novel four-point bending and internal water pressure fatigue testing system was developed to apply constant amplitude out-of-phase biaxial loading to 58 mm diameter GCI pipes at 1.7 Hz. To verify the ability of this equipment to apply known stresses and repeatable loads to pipe specimens a series of tests were conducted. A finite element model of the pipe specimen was used to estimate the strains and displacements applied by the equipment.</p><h3>Results</h3><p>Experimental strains and displacements were mainly within ± 10% of the estimated values and the pressure amplitudes measured over 10<sup>3</sup> cycles were within ± 3% of the average. Dynamic load effects occurred at higher bending loads, but these were quantified and accounted for. Trial destructive tests revealed that the lifespan of leaking fatigue cracks in GCI pipes with uniform wall-loss subject to combined internal pressure and bending fatigue loads is less than 1% of the total cycles-to-burst.</p><h3>Conclusions</h3><p>The experimental method developed was able to apply combined, out-of-phase internal pressure and bending fatigue loads accurately and consistently to small-dimeter GCI pipes, and cause these pipes to develop high-cycle fatigue regime failures.</p></div>","PeriodicalId":552,"journal":{"name":"Experimental Mechanics","volume":"65 5","pages":"605 - 623"},"PeriodicalIF":2.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11340-025-01153-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144073840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0