REVIEW 3 major objections 5 minor 40 references
Inverse Bauschinger Effect in Active Ultrastable Glasses
T0 review · 3 major / 5 minor · reviewed 2026-08-15 · deepseek-v4-flash
Pith's one-line read Active glasses flip the Bauschinger memory effect
desk verdict Plausible and novel inverse Bauschinger claim in active glasses, but missing a time-matched aging control and any statistical averaging makes the central mechanism unproven. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing object is the transient network of shear bands that forms when a fraction of particles is driven by persistent run-and-tumble forces during shear. In the two-dimensional polydisperse soft-sphere glass with $\tau_p=0.1$ and $f_0=2.0$, activity turns the single brittle shear band of a passive ultrastable glass into a gradually evolving, branched network. The network is characterized by non-affine displacements $D^2_{\min}$ and a fabric-tensor anisotropy index $\alpha$ that measures the orientation bias of interparticle contacts; both show that plastic zones and contact anisotropy coincide. When shear is reversed shortly after yielding, this network dissolves at small reverse strains, so the system has to re-nucleate shear bands and yields later and at higher stress. Further pre-strain plasticizes the network, healing fails, and the classical Bauschinger effect returns.
What would settle it
Repeat the shear-reversal protocol for $\gamma_N=0.13$, $\tau_p=0.1$, and $f_0=2.0$ on at least twenty independently prepared glass samples; if the mean reverse yield stress is not higher than the mean forward yield stress by more than the standard error, the inverse Bauschinger effect as reported is not statistically established.
Extended reading notes
Core claim
The authors claim that in a two-dimensional ultrastable glass doped with run-and-tumble active particles, reversing the shear direction at a strain just beyond yielding produces a yield stress on reverse loading that exceeds the forward yield stress—opposite to the classical Bauschinger effect. The effect appears at small pre-strains, for example $\gamma_N=0.13$ with $\tau_p=0.1$ and $f_0=2.0$, and disappears as the pre-strain grows: around $\gamma_N\approx0.26$ the forward and reverse responses become equal, and at larger strains the system returns to the classical Bauschinger response. Passive ultrastable glasses show only the classical effect. The paper connects the inverse effect to the transient healing of shear band networks: at the zero-stress state after unloading, active systems retain a network of mobile regions that anneals on reverse shear, delaying yield; at larger deformation the network becomes permanently plasticized and can no longer heal. The authors state their belief that this is the first documented inverse Bauschinger effect in amorphous solids.
Load-bearing premise
The central claim rests on the assumption that the higher reverse yield stress seen in Fig. 3(c) is a real property of the active glass and not the fluctuation of a single simulation run, since the stress-strain curves are shown without ensemble averaging, error bars, or a stated system size.
Editorial extensions
If this is right
- A glass that fails through a single shear band cannot show the inverse effect; activity-induced multi-band networks are required, so active doping is a control parameter for the sign of the Bauschinger response.
- There is a tunable crossover: small pre-strains (near $\gamma_N=0.13$) give the inverse Bauschinger effect, while larger pre-strains give the classical Bauschinger effect, so deformation history alone selects the memory response.
- Cyclic shear of active ultrastable glasses above the yield point causes progressive shear softening, with yield stress falling each cycle and a less-branched, permanent shear band network emerging before steady state.
- Reversing shear can heal a just-formed shear band network, meaning a material can be made stronger against deformation in the opposite direction, not weaker.
Reading between the lines
- The reported asymmetry rests on single trajectories; averaging over independent glass samples and reporting error bars would establish whether the inverse effect is a robust material property or a fluctuation.
- A testable prediction follows directly: turning off activity before reversal should abolish the inverse effect and restore the passive drop in residual stress, which the supplementary activity-off runs already hint at.
- The mechanism suggests that any glass that yields through a transient multi-band network—for instance passive glasses sheared at high rates—might show an inverse Bauschinger effect if the network can heal, so the phenomenon need not require activity itself.
- If the effect is robust, active particles could serve as a reversible eraser for shear history: pre-shear writes a memory, reversal erases it, and repeated cycling overwrites it with a softer steady state.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper presents molecular dynamics simulations of a two-dimensional polydisperse soft-sphere ultrastable glass doped with 20% run-and-tumble active particles, subjected to shear deformation with direction reversal at various pre-shear strains. The authors report that, unlike the passive glass which shows the classical Bauschinger effect, the active glass at low persistence time exhibits an inverse Bauschinger effect for intermediate pre-shear strains: after unloading to a zero-stress state, the yield stress under reverse shear exceeds that under forward shear. The effect is attributed to the transient healing of a network of shear bands during reverse loading, and the system is reported to cross over to the classical Bauschinger effect at larger pre-shear strains. The paper also studies oscillatory shear, reporting progressive shear softening and irreversible restructuring of shear band networks in active systems.
Significance. The claimed observation, if statistically robust, would be the first report of an inverse Bauschinger effect in an amorphous solid, and it would connect active driving to mechanically encoded directional memory in ultrastable glasses. The study has notable strengths: the effect is extracted directly from simulated stress-strain curves with no fitted parameters, a systematic scan over active force magnitude, persistence time, and pre-shear strain is presented, and the fabric-tensor anisotropy analysis provides a plausible microstructural correlate. The shear-band healing mechanism is visually supported by D2min snapshots and movies. However, the central quantitative claim rests on single realizations without reported system-size dependence or ensemble averaging, and the protocol lacks a control for activity-induced aging during the reverse test, so the significance claim is currently conditional on closing these gaps.
major comments (3)
- [Models and Methods; Section II, Fig. 3(b-f)] The central claim of an inverse Bauschinger effect is based on the relative heights of forward and reverse yield peaks in Fig. 3, but the paper does not report the system size, the number of independent configurations, or any ensemble averaging or error bars. The stress-strain curves appear to be single realizations. Since shear band formation in small two-dimensional samples is strongly realization-dependent, the reported asymmetry between forward and reverse yield stress at γN = 0.13 could be within sample-to-sample fluctuations. Please state the system size and number of independent samples and show averaged stress-strain curves with standard errors, and provide the numerical yield stresses for the states in Fig. 3(b-f) with an explicit operational definition of yield stress.
- [Section II, Fig. 3(c) and 'Healing of Shear Band Networks'] The inverse Bauschinger claim conflates time under activity with the reversal of strain direction. At the zero-stress state used for Fig. 3(c) (γN = 0.13, τp = 0.1, f0 = 2.0), the active forces are still applied and the system continues to evolve even without shear. The forward and reverse tests are separate runs starting from this state, and the reverse branch yields at a larger strain and therefore after a longer simulated time. If activity alone heals or weakens the shear band network over that interval, the elevated reverse yield stress would be a waiting-time artifact rather than evidence of directional mechanical memory. The authors must perform a control in which the same zero-stress state is aged under activity for different waiting times before shear is applied in either direction, and show that the yield stress difference is not reproduced by aging alone. The claim that 'the system heals upon shear reversal' requires such a control to distinguish direction-dependent healing from simple time-dependent relaxation.
- [Section III, Discussion; Introduction] The manuscript's central novelty claim, 'we believe that our observation of the inverse Bauschinger effect in amorphous solids could be the first documented observation', is stronger than the evidence currently supports. A literature statement that, to the authors' knowledge, no previous simulation or experiment on amorphous solids has reported an inverse Bauschinger effect should be supported by a dedicated comparison with prior work on metallic glasses, polymer glasses, and computational amorphous solids, beyond the crystalline-metal references [21-23]. If prior observations exist or are ambiguous, the claim should be reworded accordingly.
minor comments (5)
- [Section II, Fig. 3 text] The sentence 'beyond this point, the system transitions to the classical Bauschinger effect, where the yield stress in the reverse direction decreases, a phenomenon well-documented [].' contains an empty citation; please fill in the reference.
- [Section II, Fig. 3 caption and text] The text refers to 'Fig. (a)' and 'Figs. (b-f)' without the figure number; please correct these to 'Fig. 3(a)' and 'Fig. 3(b-f)' for clarity.
- [Section I, Models and Methods] Several mathematical symbols appear garbled in the text (for example, '¯Ã', 'Ãij', and the square-root radicals in Eq. (6)). Please ensure the final typeset version renders these correctly, as the current encoding makes the potential and fabric-tensor definitions hard to read.
- [Supplementary Information, Fig. 2 caption] The caption states 'parameters τp = 1.0 and f=2.0'; the active force subscript is missing and should be 'f0 = 2.0' for consistency with the main text.
- [Supplementary Information, Movie Files] The supplementary text says 'Movie Files are added', but no files or links are listed. Please provide explicit file names or links so that reviewers and readers can access the claimed visual evidence.
Circularity Check
No circularity: the inverse Bauschinger effect is measured directly from simulation stress-strain curves, with no fitted parameters or self-citation chain used to produce the central claim.
full rationale
The paper's central claim is an observed, protocol-defined comparison between forward and reverse yield stresses starting from the same pre-sheared zero-stress state. No constitutive equation is derived, no parameter is fitted, and no 'prediction' is generated from an input that already contains the answer. The 'inverse Bauschinger effect' label is an interpretation of the measured asymmetry, not a derived quantity. The only self-citation is to companion work [19] for the observation that activity promotes gradual failure and less plasticized states; this is supporting context and is also evidenced in the present data, so it does not constitute load-bearing circularity. The screening criticism about a missing aging control concerns statistical or control robustness, not circularity, and would be a correctness or reproducibility concern. Therefore no circular step is present.
Assumptions & free parameters
free parameters (4)
- active force magnitude f0 =
2.0 (varied 0.0-8.0)
- persistence time tau_p =
0.1 (varied 0.1-4.0)
- active particle fraction =
20%
- strain rate =
5e-5
assumptions (4)
- standard math SLLOD equations of motion with Gaussian thermostat correctly model simple shear for this system
- domain assumption The 4-state clock active force with net momentum conservation represents run-and-tumble activity without spurious center-of-mass drift
- domain assumption D2_min non-affine displacement and fabric tensor anisotropy index accurately identify shear bands and structural memory
- domain assumption The ultrastable glass sample prepared by swap Monte Carlo at T=0.026 and quenched to T=0.001 is representative and reproducibly prepared
Cite this review
Pith. "Pith review of Inverse Bauschinger Effect in Active Ultrastable Glasses." pith.science (2026). https://pith.science/paper/KWH5IWI2
@misc{pith2026250507356,
author = {Pith},
title = {Pith review of: Inverse Bauschinger Effect in Active Ultrastable Glasses},
year = {2026},
howpublished = {\url{https://pith.science/paper/KWH5IWI2}},
note = {Machine review of arXiv:2505.07356}
}
read the original abstract
Memory effects in amorphous materials have been widely studied because of their possible widespread future applications. We show here that ultrastable glasses can exhibit a transient reversible memory effect when subjected to both a local driving force via Run-and-tumble active particles and global shear. We investigate the system's response across different yielding regimes by selectively switching the shear direction at different strains. We analyze how changes in shear direction influence yielding, post-yield behavior, and structural evolution in active amorphous solids. Our model active system exhibits an enhanced anisotropic response, displaying both conventional and inverse Bauschinger effects, depending on the deformation history. The results indicate that activity-induced shear band networks create structural memory, enabling the system to heal upon shear reversal due to the transient nature of this phenomenon. Additionally, we observe that shear softening under cyclic loading produces an irreversible, stable, and less branched network structure with increasing cycles. These findings provide novel insights into how activity and shear collectively contribute to mechanical response, including memory formation in ultrastable disordered systems.
Figures
Figures from the paper (4 more)
Reference graph
Works this paper leans on
-
[1]
J. Bauschinger, On the behavior of cast-iron, wrought- iron and stone columns in fire, and under rapid cooling, Van Nostrand’s Engineering Magazine 35, 456
- [2]
-
[3]
A. J. Kovacs, J. J. Aklonis, J. M. Hutchinson, and A. R. Ramos, Isobaric volume and enthalpy recovery of glasses. ii. a transparent multiparameter theory, Journal of Poly- mer Science: Polymer Physics Edition 17, 1097 (1979)
work page 1979
-
[4]
E. Bouchbinder and J. Langer, Nonequilibrium thermo- dynamics of the kovacs effect, Soft Matter 6, 3065 (2010)
work page 2010
-
[5]
N. C. Keim and S. R. Nagel, Generic transient memory formation in disordered systems with noise, Phys. Rev. Lett. 107, 010603 (2011)
2011
- [6]
-
[7]
M. Adhikari and S. Sastry, Memory formation in cycli- cally deformed amorphous solids and sphere assemblies, The European Physical Journal E 41, 105 (2018)
work page 2018
-
[8]
J. D. Paulsen, N. C. Keim, and S. R. Nagel, Multi- ple transient memories in experiments on sheared non- brownian suspensions, Phys. Rev. Lett. 113, 068301 (2014)
work page 2014
Show all 40 references
-
[9]
Zou and S
L.-N. Zou and S. R. Nagel, Glassy dynamics in ther- mally activated list sorting, Phys. Rev. Lett. 104, 257201 (2010)
2010
-
[10]
Jonason, E
K. Jonason, E. Vincent, J. Hammann, J. P. Bouchaud, and P. Nordblad, Memory and chaos effects in spin glasses, Phys. Rev. Lett. 81, 3243 (1998)
1998
-
[11]
N. C. Keim, J. D. Paulsen, Z. Zeravcic, S. Sastry, and S. R. Nagel, Memory formation in matter, Rev. Mod. Phys. 91, 035002 (2019)
2019
-
[12]
S. Lu, D. Huang, C. Liang, and Y. Feng, Orientation- dependent yield and bauschinger effects in two- dimensional yukawa solids, Phys. Rev. Res. 6, 033211 (2024)
2024
-
[13]
Patinet, A
S. Patinet, A. Barbot, M. Lerbinger, D. Vandembroucq, and A. Lema ˆ ıtre, Origin of the bauschinger effect in amorphous solids, Phys. Rev. Lett. 124, 205503 (2020)
2020
-
[14]
Karmakar, E
S. Karmakar, E. Lerner, and I. Procaccia, Plasticity- induced anisotropy in amorphous solids: The bauschinger effect, Phys. Rev. E 82, 026104 (2010)
2010
-
[15]
H.-B. Yu, Y. Luo, and K. Samwer, Ultrastable metallic glass, Advanced Materials 25, 5904 (2013), https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201302700
2013 doi
-
[16]
H. J. Barlow, J. O. Cochran, and S. M. Fielding, Ductile and brittle yielding in thermal and athermal amorphous materials, Phys. Rev. Lett. 125, 168003 (2020)
2020
-
[17]
A. D. S. Parmar, M. Ozawa, and L. Berthier, Ultrastable metallic glasses in silico, Phys. Rev. Lett. 125, 085505 (2020). 10
2020
-
[18]
Rodriguez-Tinoco, M
C. Rodriguez-Tinoco, M. Gonzalez-Silveira, M. A. Ramos, and J. Rodriguez-Viejo, Ultrastable glasses: new perspectives for an old problem, Nuovo Cimento Rivista Serie 45, 325 (2022)
2022
-
[19]
Priya, J
R. Priya, J. Horbach, and S. Karmakar, Mitigating brittle failure in ultrastable glasses via active particles doping, Manuscript in preparation (2025)
2025
-
[20]
Singh, M
M. Singh, M. Ozawa, and L. Berthier, Brittle yielding of amorphous solids at finite shear rates, Phys. Rev. Mater. 4, 025603 (2020)
2020
-
[21]
J. Zhou, J. Shen, F. Essa, and J. Yu, Twins and grain boundaries-dominated the reverse bauschinger effect and tension-compression asymmetry, Journal of Materials Re- search and Technology 18, 15 (2022)
2022
-
[22]
Koizumi and M
T. Koizumi and M. Kuroda, Measurement of bauschinger effect in ultrafine-grained a1070 aluminum rods, Key En- gineering Materials 725, 202 (2016)
2016
-
[23]
Lopes, E
W. Lopes, E. C. S. Corrˆ ea, H. B. Campos, M. T. P. Aguilar, and P. R. Cetlin, Effect of reverse and cyclic shear on the work-hardening of aisi 430 stainless steel, J. Mater. Sci. 44, 441 (2009)
2009
-
[24]
A. D. S. Parmar, S. Kumar, and S. Sastry, Strain local- ization above the yielding point in cyclically deformed glasses, Phys. Rev. X 9, 021018 (2019)
2019
-
[25]
Radjai, H
F. Radjai, H. Troadec, and S. Roux, Key features of gran- ular plasticity, Granular materials: Fundamentals and applications , 157 (2004)
2004
-
[26]
Similarly, our study also observes this behavior
shows that amorphous silica develops permanent anisotropy when subjected to external shear. Similarly, our study also observes this behavior. The anisotropy parameter derived from the fabric tensor can effectively capture structural anisotropy and helps in analyzing how shear a...
-
[27]
P. Das, A. D. S. Parmar, and S. Sastry, An- nealing glasses by cyclic shear deformation, The Journal of Chemical Physics 157, 044501 (2022), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/5.0100523/16651060/044501 1 online.pdf
2022 doi
-
[28]
C. L. Rountree, D. Vandembroucq, M. Talamali, E. Bouchaud, and S. Roux, Plasticity-induced structural anisotropy of silica glass, Phys. Rev. Lett. 102, 195501 (2009)
2009
-
[29]
W.-T. Yeh, M. Ozawa, K. Miyazaki, T. Kawasaki, and L. Berthier, Glass stability changes the nature of yield- ing under oscillatory shear, Phys. Rev. Lett. 124, 225502 (2020)
2020
-
[30]
Fiocco, G
D. Fiocco, G. Foffi, and S. Sastry, Oscillatory athermal quasistatic deformation of a model glass, Phys. Rev. E 88, 020301 (2013)
2013
-
[31]
Bhaumik, G
H. Bhaumik, G. Foffi, and S. Sastry, Yielding transition of a two dimensional glass former under athermal cyclic shear deformation, The Journal of Chemical Physics 156, 064502 (2022), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/5.0085064/16536503/064502 1 online.pdf
2022 doi
-
[32]
Leishangthem, A
P. Leishangthem, A. D. S. Parmar, and S. Sastry, The yielding transition in amorphous solids under oscillatory shear deformation, Nature Communications 8, 14653 (2017)
2017
-
[33]
Ninarello, L
A. Ninarello, L. Berthier, and D. Coslovich, Models and algorithms for the next generation of glass transition studies, Phys. Rev. X 7, 021039 (2017)
2017
-
[34]
P. K. Jana and N. V. Priezjev, Structural relaxation in amorphous materials under cyclic tension-compression loading, Journal of Non-Crystalline Solids 540, 120098 (2020)
2020
-
[35]
Zhang, D
F. Zhang, D. J. Searles, D. J. Evans, J. S. den Toom Hansen, and D. J. Isbister, Kinetic energy conserving integrators for Gaussian ther- mostatted SLLOD, The Journal of Chemical Physics 111, 18 (1999), https://pubs.aip.org/aip/jcp/article- pdf/111/1/18/19147906/18 1 online.pdf
1999
-
[36]
Berthier, E
L. Berthier, E. Flenner, C. J. Fullerton, C. Scalliet, and M. Singh, Efficient swap algorithms for molecular dynam- ics simulations of equilibrium supercooled liquids, Jour- nal of Statistical Mechanics: Theory and Experiment 2019, 064004 (2019)
2019
-
[37]
M. P. Allen and D. J. Tildesley, Computer Simulation of Liquids (Oxford University Press, 2017)
2017
-
[38]
G. Pan, J. F. Ely, C. McCabe, and D. J. Isbister, Oper- ator splitting algorithm for isokinetic SLLOD molecular dynamics, The Journal of Chemical Physics 122, 094114 (2005), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/1.1858861/15362086/094114 1 online.pdf
2005 doi
-
[40]
M. L. Falk and J. S. Langer, Dynamics of viscoplastic deformation in amorphous solids, Phys. Rev. E 57, 7192 (1998). Supplementary Information - Inverse Bauschinger Effect in Active Ultra stable Glasses Rashmi Priya 11 and Smarajit Karmakar 11 11 Tata Institute of Fundamental R...
1998
-
[4007]
Most computations are performed using the HPC clusters procured through Swarna Jayanti Fellowship grants DST/SJF/PSA01/2018-19 and SB/SFJ/2019- 20/05
SK acknowledges Swarna Jayanti Fellowship grants DST/SJF/PSA01/2018-19 and SB/SFJ/2019- 20/05 from the Science and Engineering Research Board (SERB) and Department of Science and Technology (DST). Most computations are performed using the HPC clusters procured through Swarna J...
2018
Reviewed August 15, 2026 · model on record in the stance chip above.
Discussion (0). Continue with ORCID to comment.