Shear Amplitude Research Articles

Ultrastable Shear-Jammed Granular Material

Dry granular materials, such as sand, gravel, pills, or agricultural grains, can become rigid when compressed or sheared. Under isotropic compression, the material reaches a certain jamming density and then resists further compression. Shear jamming occurs when resistance to shear emerges in a system at a density lower than the jamming density. Although shear jamming is prevalent in frictional granular materials, their stability properties are not well described by standard elasticity theory and thus call for experimental characterization. We report on experimental observations of changes in the mechanical properties of a shear-jammed granular material subjected to small-amplitude, quasistatic cyclic shear. We study a layer of plastic disks confined to a shear cell, using photoelasticimetry to measure all interparticle vector forces. For sufficiently small cyclic shear amplitudes and large enough initial shear, the material evolves to an unexpected “ultrastable” state in which all the particle positions and interparticle contact forces remain unchanged after each complete shear cycle for thousands of cycles. The stress response of these states to small imposed shear is nearly elastic, in contrast to the original shear-jammed state.5 MoreReceived 14 January 2022Revised 18 May 2022Accepted 8 July 2022DOI:https://doi.org/10.1103/PhysRevX.12.031021Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCollective behaviorDynamical phase transitionsElasticityFatigueGranular materialsJammingMechanical deformationRheologyStatistical PhysicsInterdisciplinary PhysicsCondensed Matter, Materials & Applied PhysicsNetworksPolymers & Soft Matter

Strain‐hardening and breakdown in poly(vinylidene fluoride) gels in methyl‐ethyl‐ketone and heptanone

AbstractGelation kinetics and rheological properties of poly(vinylidene fluoride‐co‐hexafluoropropylene) [P(VDF‐co‐HFP)] solutions in methyl‐ethyl‐ketone and in 2‐heptanone are investigated. Small‐angle X‐ray scattering measurements indicate that the systems undergo phase separation by a nucleation process. For concentrations between 6 and 10 wt% of copolymer, strain‐hardening appears when gels are sheared in the nonlinear regime, around 50% of deformation. At some critical shear amplitude, the rheological response changes abruptly, but reversibly, from hyperelastic towards viscous liquid. This indicates that the system undergo fracture or shear banding, in bulk or at walls. In other words the continuous network formed by the elastic, polymer‐rich phase is locally broken under high amplitude oscillatory shear, thus breaking down the overall elastic response of the material. More interestingly, when the strain amplitude is progressively decreased back to zero, the initial nonlinear viscoelastic behavior is quantitatively recovered. In addition, when the strain is removed, the solution turns back to gel state very fast as compared with thermal gelation kinetics. These observations indicate that the initial structure can heal within a short time. It is proposed that strain‐hardening depends on the intrinsic hyperelastic behavior of the polymer‐rich phase, which should have a high density of effective crosslinks and/or entanglements.

Lymphangion‐Chip Experimental Platform Supports Co‐culture and Signaling Between Lymphatic Endothelial and Mural Cells

The pathophysiology of several lymphatic diseases, such as lymphedema, depends on the function of lymphangions that drive lymph flow. Even though the signaling between two main cellular components of a lymphangion, Lymphatic Endothelial Cells (LECs) and Lymphatic Muscle Cells (LMCs), is responsible for crucial lymphatic functions, there are no in vitro models that have included both cell types in a physiologically relevant environment. Here, a fabrication technique (Gravitational Lumen Patterning or GLP) is developed to create Lymphangion‐Chip. This organ‐on‐chip consists of co‐culture of a monolayer of endothelial lumen surrounded by multiple and uniformly thick layers of muscle cells. The platform allows construction of a wide range of luminal diameters and muscular layer thicknesses, thus providing a toolbox to create variable anatomy. In this device, lymphatic muscle cells align circumferentially while endothelial cells aligned axially under flow, as only observed in vivo in the past. This model further demonstrated a robust sensitivity of this relative alignment of the two cells with respect to the presence or absence of co‐culture and mechanical forces (shear stress), thus suggesting that LECs and LMCs are biologically and functionally active within the chip. This system successfully characterizes the dynamics of cell size, density, growth, alignment, and intercellular gap due to co‐culture and shear. The time‐dependent decrease in the subendothelial gap strongly suggests proactive LEC‐LMC signaling as LECs and LMCs grow and proliferate within the device. Further exposure to pro‐inflammatory cytokines reveals that the device could produce the regulation of endothelial barrier function through the lymphatic muscle cells. Finally, measurement of intracellular calcium of LECs and LMCs while exposed to step and oscillatory flow profiles with various shear amplitudes revealed the bidirectional mechanism of calcium signaling within lymphatic vessel. Therefore, this organ‐chip technology allows researchers to include essential lymphatic vascular components in a tunable 3D microphysiological system that is suitable for use in preclinical research of lymphatic and blood mechanobiology, inflammation, and translational outcomes.

Abstract 378: Lymphangion-chip: It Recreates Intercellular Signaling Between Lymphatic Vascular Endothelial And Mural Cells In Health And Disease

The pathophysiology of several lymphatic diseases, such as lymphedema, depends on the function of lymphangions. Even though the signaling between two main cellular components of a lymphangion, Lymphatic Endothelial Cells (LECs) and Lymphatic Muscle Cells (LMCs), is responsible for crucial functions, there are no in vitro models that have included both cell types in a physiologically relevant environment. Here, a fabrication technique is developed to create a Lymphangion-Chip. This organ-on-chip consists of co-culture of a monolayer of endothelial lumen surrounded by multiple and uniformly thick layers of muscle cells. The platform allows construction of a wide range of luminal diameters and muscular layer thicknesses, thus providing a toolbox to create variable anatomy. In this device, the muscle cells align circumferentially while endothelial cells aligned axially under flow, as only observed in vivo in the past. This model further demonstrated a robust sensitivity of this relative alignment of the two cells as well as dynamics of cell size, density, growth, and intercellular gap with respect to the presence or absence of co-culture and mechanical forces (shear). The time-dependent decrease in the subendothelial gap strongly suggests proactive LEC-LMC signaling as LECs and LMCs grow and proliferate within the device. Further exposure to pro-inflammatory cytokines reveals that the device could produce the regulation of endothelial barrier function through the muscle cells. Finally, measurement of intracellular calcium of LECs and LMCs while exposed to step and oscillatory flow profiles with various shear amplitudes revealed the bidirectional mechanism of calcium signaling within the platform. Therefore, this technology allows researchers to include essential lymphatic vascular components in a tunable 3D microphysiological system that is suitable for use in preclinical research of lymphatic mechanobiology, inflammation, and translational outcomes.

Perpendicular heating of ions by low-frequency polarized Alfvén waves

The expression for the perpendicular saturation temperature of ions heated by a low-frequency shear Alfvén wave due to nonresonant interaction in low-β plasmas has been derived. This expression is closely related to the frequency, polarization, and amplitude of the low-frequency shear Alfvén wave. The derived expression has been verified by performing simulations. Because of the Doppler effect, the saturation temperature is different for different polarized waves. The saturation value of the perpendicular ion temperature has a lower limit for the left-handed polarized Alfvén wave and a higher limit for the right-handed polarized Alfvén wave. The results might be helpful to explain the heating of ions in the solar wind.

Spatial correlation of irreversible displacement in oscillatory-sheared metallic glasses

We report computer simulations on the oscillatory of CuZr metallic glasses at zero temperature with different shear amplitudes. In small system a homogenous shear deformation is found, while in large system an inhomogeneous shear deformation is found with a shear band formed. Concomitantly, spatial correlation of irreversible displacement exhibits an isotropic and exponential decay in the case of homogeneous deformation, whereas a mixed power-law and exponential decay in the case of anisotropic and inhomogeneous deformation. By projecting the azimuthal-dependent correlation function onto the spherical harmonics, we found a strong polar symmetry that accounts for the emerged shear band, and a weaker quadrupolar symmetry that accounts for the elastic filed generated by Eshelby inclusions. By this, we conclude that the anisotropy and decaying formula of the plastic correlation are dominated by the homogeneity or inhomogeneity for the deformation in the metallic glasses.

Testing of Fabric Reinforced Cementitious Matrix in Shear without Substrate

This paper aims at investigating the matrix-to-textile stress transfer in a fabric reinforced cementitious matrix FRCM system, not bonded to any substrate, under shear loads. To this end, direct shear tests are performed on a basalt FRCM specimen introduced into an innovative properly designed four-hinge frame loaded by a universal testing machine. The role of the single components in the global shear behavior of the FRCM is experimentally analyzed. Digital image correlation (DIC) is adopted for evaluating both the displacement and strain fields as well as for detecting the damage. Furthermore, the shear response of the tested FRCM material is reproduced via an effective numerical approach that considers the nonlinear behavior of the mortar and the possible micro-mechanisms that arise between the textile and the matrix, introducing suitable interfaces joining the FRCM constituent layers, i.e. textile and mortar layers. Experimental outcomes highlighted the non-negligible influence of the matrix in the shear response of the composite, both in strength and stiffness. The proven DIC technique demonstrated to be suitable also for this novel test type, since it allows to obtain shear strains, location and amplitude of cracks with satisfying accuracy, such as to make direct shear tests results a benchmark to be used for numerical simulations. Numerical analyses are performed in order to verify the efficiency of the proposed model in reproducing the mechanical behavior of FRCM composites under shear loads and in describing the damage patterns during the loading process.

Rheological elucidation of the viscoelastic properties and network interaction of mixed high-methoxyl pectin and kappa-carrageenan gels

The interaction between two anionic polysaccharides known for their gelation capability was investigated. Mixtures of high-methoxyl pectin (HMP) and κ-carrageenan (KC) were prepared at different volume fractions. The sample's complex rheological properties and microstructures were investigated by performing linear small amplitude oscillatory shear (SAOS) and nonlinear large amplitude oscillatory shear (LAOS). Pure KC and the HMP/KC mixtures exhibited gel-like properties, whereas pure HMP did not gel at the experimental conditions employed and was characterized as a viscoelastic liquid. Temperature-dependent rheological behavior of HMP/KC mixtures suggested the independent aggregation of KC chains. The viscoelastic properties of the HMP/KC mixtures, such as oscillatory spectrum, and material stiffness, followed that of pure KC, indicating that KC strongly influenced the final gel. The transient behavior of the HMP/KC mixtures in the time sweep and the monotonic decrease of the storage modulus in the linear regime, and the onset of nonlinear rheological behavior in the strain sweep measurements suggested the possibility of the phase-separated network structure of in HMP-rich and KC-rich phases in the mixtures. Based on the rheological data both in the linear and nonlinear regimes, we propose the possibility of a bicontinuous network structure in HMP/KC mixtures, composed of the weak HMP phase in random coil configuration and the dominant KC phase in double helix aggregates.

OrthoChirp: A fast spectro-mechanical probe for monitoring transient microstructural evolution of complex fluids during shear

Shear-induced microstructural changes are observed ubiquitously in materials as diverse as hydrogels, or drilling fluids, as well as many consumer products. Superposition rheometry, consisting of superimposing Small Amplitude Oscillatory Shear (SAOS) on top of a constant rate unidirectional shear has often been used to gain insight into these shear-induced changes. Orthogonal superposition (OSP), in which the two modes of deformation are perpendicular, has been preferred over parallel superposition to avoid non-linear cross-coupling of the steady shear and small amplitude oscillatory deformation fields. This cross-coupling can lead to unphysical sign changes in the measured material properties, and makes it difficult to unambiguously interpret the flow-induced mechanical properties. Recently, orthogonal superposition has been used to investigate the shear-induced anisotropy produced in colloidal gels by comparing the transient evolution of the orthogonal moduli with the parallel moduli immediately after cessation of shear. However, probing transient evolution using the OSP technique can be challenging for rapidly mutating complex materials which evolve on time scales comparable to the time scale of the experiment. Using a weakly associated alginate gel, we demonstrate the potential to substantially reduce the measurement time by superimposing fast Optimally Windowed Chirp (OWCh) deformations orthogonally to the steady shearing deformation. We evaluate the changes in the rate-dependent relaxation spectrum in the direction of the applied unidirectional shear rate, as well as in the orthogonal direction, by measuring the damping function and shear-induced changes in the orthogonal moduli respectively. We observe systematic differences between the two sets of spectra that we measure in the two orthogonal directions, enabling us to quantify the flow-induced generation of microstructural anisotropy in the alginate gel. • Reduction of measurement time for orthogonal superposition (OSP) rheometry. • Possible to superpose optimally windowed chirps (OWCh) orthogonally to steady shear. • Shear flow induces microstructural anisotropy in weakly associating alginate gels. • Observation of transient evolutions in rapidly mutating complex materials • Different rate-dependent relaxation spectra in orthogonal directions.

Characterization of highly stable water-based magnetorheological gel using OPTIGEL-WX as an additive: The study of magneto-induced rheological and viscoelastic properties

In this work novel kinds of highly stable MR gels were prepared by suspending flake-shaped micron-sized carbonyl iron (CI) particles into water/OPTIGEL-WX suspension, OPTIGEL-WX is a promising additive that forms a gel-like structure with water. We found that surface tension decreases when the concentration of OPTIGEL-WX was raised, and the contact angle increased due to a stronger adhesive force at the liquid–air interface between the host liquid molecules and the CI particles. We examined magneto-induced rheological and viscoelastic properties using Anton-Paar (MCR-102) rheometer. The theoretical Bingham model was used to fit the experimental shear stress versus shear rate curves and observed static and dynamic yield stress values were substantially identical. Amplitude sweep showed that the linear viscoelastic region (LVE) was obtained approximately at 0.1% of shear strain. A crossover point, modulusG'&G", and yield stress were enhanced as the magnetic field was increased. Frequency sweep showed that the storage modulus shows an increasing trend with the increase of frequency at first, while at higher frequency range storage modulus shows a steady plateau area. Time-dependent shear flow and amplitude sweep tests revealed complete reversibility of rheological and viscoelastic properties of the MR gel with time after destroying the microstructures.

Correlation between plastic rearrangements and local structure in a cyclically driven glass.

The correlation between the local structure and the propensity for structural rearrangements has been widely investigated in glass forming liquids and glasses. In this paper, we use the excess two-body entropy S2 and tetrahedrality ntet as the per-particle local structural order parameters to explore such correlations in a three-dimensional model glass subjected to cyclic shear deformation. We first show that for both liquid configurations and the corresponding inherent structures, local ordering increases upon lowering temperature, signaled by a decrease in the two-body entropy and an increase in tetrahedrality. When the inherent structures, or glasses, are periodically sheared athermally, they eventually reach absorbing states for small shear amplitudes, which do not change from one cycle to the next. Large strain amplitudes result in the formation of shear bands, within which particle motion is diffusive. We show that in the steady state, there is a clear difference in the local structural environment of particles that will be part of plastic rearrangements during the next shear cycle and that of particles that are immobile. In particular, particles with higher S2 and lower ntet are more likely to go through rearrangements irrespective of the average energies of the configurations and strain amplitude. For high shear, we find very distinctive local order outside the mobile shear band region, where almost 30% of the particles are involved in icosahedral clusters, contrasting strongly with the fraction of <5% found inside the shear band.

Using laboratory data to understand how pore aspect ratio influences elastic parameters and amplitude variation with offset

Pore geometry is an important parameter in reservoir characterization that affects the permeability of reservoirs and can also be a controlling factor on the impact of pressure and saturation on reservoirs elastic properties. We have used selective laser sintering 3D printing technology to build physical models to experimentally investigate the impacts of pore aspect ratio on compressional (P-) and shear wave (S-wave) velocities and amplitude variation with offset (AVO). We printed six models to study the effects of the pore aspect ratio of prolate and oblate pore structures on elastic properties and AVO signatures. We found that the P-wave velocity is reduced by decreasing the pore aspect ratio (flatter pore structure), whereas the S-wave velocity is less sensitive to the pore aspect ratio. This effect is reduced when the samples are water saturated. We developed new experimental and processing techniques to extract realistic AVO signatures from our experimental data and found that the pore aspect ratio has similar effects on AVO as fluid compressibility. This indicated that not considering the pore aspect ratio in AVO analysis can lead to misleading interpretations. We also found that these effects are reduced in water-saturated samples.

Tactile friction and rheological studies to objectify sensory properties of topical formulations

The aim of the work was to identify the physical parameters relevant to different perceptual attributes by comparing a range of commercial skin creams with various compositions. We investigated the possibility of predicting sensory properties using rheological and tribological methods. Rheological evaluations of the skin creams were carried out using continuous shear, creep, creep recovery, rheodestruction and recovery measurements, oscillatory strain sweep measurements [small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS)], and frequency sweep measurements. Friction measurements were performed on the nonbiological skin model to investigate how surface properties are influenced by the application of different topical formulations. Furthermore, the formulations were characterized by a broad range of instrumental texture measurements. In vivo sensory analysis based on the spectrum descriptive analysis method was performed to discriminate the skin creams during pickup, rub out, and after feel. Using principal component analysis meaningful correlation relating rheotribological properties and sensory attributes during the entire process of product application was carried out. Rheological parameters deduced from the nonlinear regime were found to be important parameters affecting the frictional response of skin creams. In addition, friction data were correlated with slipperiness and stickiness—subjective attributes used for the sensory evaluation of after feel. Furthermore, a number of key textural parameters and sensorial data showed good correlation with results obtained from linear and nonlinear rheological measurement, indicating rheological analysis can be sufficiently used as a precise and valid tool for sensorial mapping of topical formulations. Our study further suggests that objective evaluation based on the flow curve, oscillatory strain sweep (SAOS and LAOS), and friction measurements can be used for sensorial screening of large number of prototype formulations, which otherwise may be time consuming and costly using a sensory panel.

Turbulent-like velocity fluctuations in two-dimensional granular materials subject to cyclic shear.

We perform a systematic experimental study to investigate the velocity fluctuations in the two-dimensional granular matter of low and high friction coefficients subjected to cyclic shear of a range of shear amplitudes, whose velocity fields are strikingly turbulent-like with vortices of different scales. The scaling behaviors of both the transverse velocity power spectra ET(k) ∝ k-αT and, more severely, the longitudinal velocity power spectra EL(k) ∝ k-αL are affected by the prominent peak centered around k ≈ 2π of the inter-particle distance due to the static structure factor of the hard-particle nature in contrast to the real turbulence. To reduce the strong peak effect to the actual values of αν (the subscript 'ν' refers to either T or L), we subsequently analyze the second-order velocity structure functions of S(2)ν(r) in real space, which show the power-law scalings of S(2)ν(r) ∝ rβν for both modes. From the values of βν, we deduce the corresponding αν from the scaling relations of αν = βν + 2. The deduced values of αν increase continuously with the shear amplitude γm, showing no signature of yielding transition, and are slightly larger than αν = 2.0 at the limit of γm → 0, which corresponds to the elastic limit of the system, for all γm. The inter-particle friction coefficients show no significant effect on the turbulent-like velocity fluctuations. Our findings suggest that the turbulent-like collective particle motions are governed by both the elasticity and plasticity in cyclically sheared granular materials.

The Edwards volume ensemble in cyclically sheared granular experiments.

We experimentally investigate the Edwards volume ensemble in cyclically sheared bidisperse disks of two friction coefficients (μ ≈ 0.3 and μ → ∞) subjected to a range of shear amplitudes γm. Despite the local and global anisotropy, hysteresis, and the potential long-range correlation of the free volume, the Edwards volume ensemble surprisingly provides an excellent statistical description of disk packings in cyclically sheared systems. Our finding can be better understood from the comprehensive analysis of the geometric and statistical properties of Voronoi cells of individual particles. First, the average degrees of anisotropy of Voronoi cells are weak at both the microscopic and macroscopic scales within a range of shear amplitudes γm of up to γm = 12% regardless of the inter-particle friction coefficients μ even though the azimuthal distributions of the Voronoi cell depend on μ. Second, there is only negligible hysteresis of global compactivity and volume fluctuations. Finally, the spatial correlations of the free volume and the orientation are weakly anisotropic and short ranged for practical purposes. Both results are independent of μ. Interestingly, our free-volume statistical results are consistent with the simple physical picture that the free volume is directly proportional to the compactivity.

Bijel rheology reveals a 2D colloidal glass wrapped in 3D.

We present rheological evidence demonstrating the glass-like nature of bicontinuous interfacially jammed emulsion gels (bijels). Under small amplitude oscillatory shear, bijels exhibited rheological signatures akin to α and β relaxation that are also invariable to interfacial tension changes, behaviors which are reminiscent of caged particle dynamics found in colloidal glasses, and well described by a previously reported adaptation of mode-coupling theory for colloidal glass rheology. Guided by their rheological signatures and supported by particle detachment and attraction energy approximations, we rationalize that bijels can be represented as 2-dimensional (2D) colloidal glasses that percolate in 3-dimensional (3D) space, and attractive interactions are not required for their stability. To provide further support for this conjecture, we qualitatively compare the rheology of bijels and a capillary suspension that is stabilized by strong, rigid capillary bridges between the particles, beyond their limit of linear viscoelasticity. Our results demonstrate that the strong adsorption of particles to the continuous interface and the lack of strong attractive interparticle forces enable recovery by interfacial tension into new jammed configurations after shear deformation. These behaviors are qualitatively different from those in the capillary suspension, where the breaking of attractive interparticle bonds results in dramatic changes to the microstructure and rheology over a narrow range of shear amplitudes. Our findings unveil bijels as 2D colloidal glasses weaving in 3D space and establish that interparticle attractions are not required for stability in bijels, and interfacial jamming alone is sufficient to impart viscoelasticity and gel-like rheology to these materials.

Study of the transition from amorphous to crystalline phase in a granular system under shearing and vibration

We study a slightly tilted bidimensional vibrated hard-sphere system under periodic shearing as a macroscopic model for glass-crystal phase transition. The system starts close to a random closed packed (RCP) state, modeling an amorphous solid, and rearranges into a hexagonal closed packed (HCP) crystal configuration. The vibration is fixed in amplitude and frequency, modeling a constant temperature. Periodical deformations of a rhomboidal shape boundary provide an alternating shearing. Under these conditions, the system evolves toward an ordered arrangement by an annealing process. To characterize the order, we used the sixth-bond-orientational order parameter ψ6′ which is determined for each particle using the nearest neighbors obtained from the Delaunay criterion triangulation with the additional imposition that neighbors be in touch with the particle. We report the results of seven experimental cases where the maximum deformation shear amplitude is varied. We found correlations between shear amplitude with the average of the sixth-bond-orientational order parameter. The results indicate that the cyclic perturbation determines complex oscillatory hexagonal order dynamics. It is found correlations between the sheared boundary’s acceleration with the rate of change of ψ6′.

Influence of an electric field on flexopolarization induced by acoustic action on a liquid crystal

The work experimentally investigated the influence of an electric field on the direct flexoelectric effect that occurs under the influence of an acoustic field in liquid crystals. Thin layers of nematics 10-100 μm thick were studied. In this case, the liquid crystal sample was exposed to the piston method with an acoustic wave with a frequency of 1 kHz. The dependences of the first and second harmonics for different NLCs on the bias voltage value, shear amplitude, and crystal thickness were obtained. It was revealed that the flexosignal harmonics depend on the direction of the electric field; when a positive potential is applied to the movable plate, they take on smaller values than when negative. It was found that in low fields the magnitude of the flexosignal increases due to an increase in the amplitude of the director deviation, but at a critical value of the field it is suppressed, since the layer is stabilized by a constant electric field.

Geometrical properties of mechanically annealed systems near the jamming transition.

Geometrical properties of two-dimensional mixtures near the jamming transition point are numerically investigated using harmonic particles under mechanical training. The configurations generated by the quasi-static compression and oscillatory shear deformations exhibit anomalous suppression of the density fluctuations, known as hyperuniformity, below and above the jamming transition. For the jammed system trained by compression above the transition point, the hyperuniformity exponent increases. For the system below the transition point under oscillatory shear, the hyperuniformity exponent also increases until the shear amplitude reaches the threshold value. The threshold value matches with the transition point from the point-reversible phase where the particles experience no collision to the loop-reversible phase where the particles' displacements are non-affine during a shear cycle before coming back to an original position. The results demonstrated in this paper are explained in terms of neither of universal criticality of the jamming transition nor the nonequilibrium phase transitions.

First- and third-order shear nonlinearities across the structural relaxation peak of the deeply supercooled pharmaceutical liquid indomethacin

Nonlinear rheological properties of viscous indomethacin are studied in the frequency range of its structural relaxation, that is, in a range so far inaccessible to standard techniques involving medium-amplitude oscillatory shear amplitudes. The first- and third-order nonlinearity parameters thus recorded using a sequence of small and large shear excitations in a time efficient manner are compared with predictions from rheological models. By properly phase cycling the shear amplitudes, build-up and decay transients are recorded. Analogous to electrical-field experiments, these transients yield direct access to the structural relaxation times under linear and nonlinear shearing conditions. To demonstrate the broader applicability of the present approach, transient analyses are also carried out for the glass formers glycerol, ortho-terphenyl, and acetaminophen.