@article{63435,
author = {{Claes, Leander and Winkler, Michael}},
issn = {{1468-1218}},
journal = {{Nonlinear Analysis: Real World Applications}},
pages = {{104580}},
publisher = {{Elsevier BV}},
title = {{{Describing smooth small-data solutions to a quasilinear hyperbolic-parabolic system by W 1,P energy analysis}}},
doi = {{10.1016/j.nonrwa.2025.104580}},
volume = {{91}},
year = {{2026}},
}
@inproceedings{65625,
author = {{Friesen, Olga and Hölscher, Jonas and Siegmund, Michael B. K. and Claes, Leander and Henning, Bernd}},
title = {{{Experimental and Numerical Investigation of Jump Phenomena in the Frequency Response of Piezoelectric Systems}}},
year = {{2026}},
}
@article{65785,
abstract = {{Simulation-based design of high-power ultrasonic systems depends on the accurate modelling of the electromechanical behaviour of piezoceramic materials. In practical transducer applications, the relevant operating points are influenced by mechanical preload and heating, both of which give rise to changes in the elastic, dielectric, and piezoelectric material properties. Material parameters identified under idealised, unloaded conditions are therefore insufficient to represent piezoceramic material behaviour under realistic operating conditions. To overcome this limitation, experimental setups are developed that enable the measurement of electrical impedance spectra under controlled thermal and mechanical conditions. The acquired impedance data are used in an inverse identification procedure, in which the behaviour of a finite element forward model is iteratively fitted to the measurements using a block coordinate descent optimisation strategy guided by a sensitivity analysis. This yields effective linear material parameters as a function of temperature and mechanical stress at varying operating points. The identified temperature-dependent parameters, for instance, can be employed in a coupled thermo-electromechanical simulation framework to predict the temperature-dependent material behaviour during operation. The linear identification based on varying operation points provides an initial approximation of the nonlinear material response, establishing a basis for the development of corresponding nonlinear material models.}},
author = {{Friesen, Olga and Claes, Leander and Hölscher, Jonas and Henning, Bernd and Scheidemann, Claus and Hemsel, Tobias and Kuess, Raphael and Walther, Andrea and Spieker, Carsten and Förstner, Jens}},
issn = {{0171-8096}},
journal = {{tm - Technisches Messen}},
keywords = {{tet_topic_piezo}},
publisher = {{Walter de Gruyter GmbH}},
title = {{{Measurement of multiphysical material parameters of piezoceramic components for high-power ultrasonic applications}}},
doi = {{10.1515/teme-2026-0042}},
year = {{2026}},
}
@inproceedings{65588,
author = {{Spieker, Carsten and Kuess, Raphael and Walther, Andrea and Förstner, Jens}},
booktitle = {{Fortschritte der Akustik - DAGA 2026}},
keywords = {{tet_topic_piezo}},
pages = {{1066–1069}},
title = {{{Modellierung und Simulation des temperaturabhängigen Materialverhaltens von Piezokeramiken mit FEniCS}}},
doi = {{10.71568/DAGA2026.549}},
year = {{2026}},
}
@article{66060,
author = {{Claes, Leander and Winkler, Michael}},
issn = {{1420-9004}},
journal = {{Nonlinear Differential Equations and Applications NoDEA}},
number = {{4}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Local strong solutions in a quasilinear Moore-Gibson-Thompson type model for thermoviscoelastic evolution in a standard linear solid}}},
doi = {{10.1007/s00030-026-01239-7}},
volume = {{33}},
year = {{2026}},
}
@inproceedings{66604,
author = {{Friesen, Olga and Hölscher, Jonas and Spieker, Carsten and Förstner, Jens and Claes, Leander}},
location = {{München}},
title = {{{Quantitative Modelling of Dynamic Nonlinearity in Piezoelectric Components}}},
year = {{2026}},
}
@inproceedings{62300,
author = {{Claes, Leander and Hölscher, Jonas and Friesen, Olga and Scheidemann, Claus and Hemsel, Tobias and Henning, Bernd}},
booktitle = {{2025 International Congress on Ultrasonics}},
pages = {{142–145}},
publisher = {{AMA Service GmbH}},
title = {{{Estimation of third order elastic constants of piezoceramics using DC biased impedance measurements}}},
doi = {{10.5162/ultrasonic2025/a18-a6}},
year = {{2025}},
}
@article{59258,
author = {{Winkler, Michael}},
issn = {{0095-4616}},
journal = {{Applied Mathematics & Optimization}},
number = {{2}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Rough Data in an Evolution System Generalizing 1D Thermoviscoelasticity with Temperature-Dependent Parameters}}},
doi = {{10.1007/s00245-025-10243-9}},
volume = {{91}},
year = {{2025}},
}
@inproceedings{61755,
author = {{Scheidemann, Claus and Hemsel, Tobias and Sextro, Walter}},
location = {{Vilnius, Lithuania}},
title = {{{Time dependent material characteristics of prestressed piezoelectric ceramics in langevin transducers}}},
year = {{2025}},
}
@inproceedings{61757,
author = {{Scheidemann, Claus and Porzenheim, Julius and Hemsel, Tobias and Sextro, Walter}},
location = {{Paderborn, Germany}},
title = {{{Investigation of the Setting Behaviour of Mechanically Biased Piezoelectric Ultrasonic Transducers}}},
year = {{2025}},
}
@article{62000,
author = {{Claes, Leander and Koch, Kevin and Friesen, Olga and Meihost, Lars}},
issn = {{2681-4617}},
journal = {{Acta Acustica}},
number = {{65}},
publisher = {{EDP Sciences}},
title = {{{Machine Learning-Supported Inverse Measurement Procedure for Broadband, Temperature Dependent Piezoelectric Material Parameters}}},
doi = {{10.1051/aacus/2025044}},
volume = {{9}},
year = {{2025}},
}
@article{54837,
author = {{Claes, Leander and Lankeit, Johannes and Winkler, Michael}},
issn = {{1793-6314}},
journal = {{Mathematical Models and Methods in Applied Sciences}},
number = {{11}},
pages = {{2465--2512}},
publisher = {{World Scientific Pub Co Pte Ltd}},
title = {{{A model for heat generation by acoustic waves in piezoelectric materials: Global large-data solutions}}},
doi = {{10.1142/s0218202525500447}},
volume = {{35}},
year = {{2025}},
}
@inproceedings{62299,
author = {{Friesen, Olga and Scheidemann, Claus and Claes, Leander and Hemsel, Tobias and Henning, Bernd}},
booktitle = {{2025 International Congress on Ultrasonics}},
pages = {{138–141}},
publisher = {{AMA Service GmbH}},
title = {{{Sensitivity Analysis and Material Parameter Estimation of a Pre-Stressed Langevin Transducer}}},
doi = {{10.5162/ultrasonic2025/a18-a4}},
year = {{2025}},
}
@inproceedings{62298,
author = {{Kuess, Raphael and Friesen, Olga and Henning, Bernd and Walther, Andrea}},
booktitle = {{2025 International Congress on Ultrasonics}},
pages = {{134–137}},
publisher = {{AMA Service GmbH}},
title = {{{Identification of temperature-dependent material parameter functions in piezoelectricity}}},
doi = {{10.5162/ultrasonic2025/a18-a3}},
year = {{2025}},
}
@inproceedings{59689,
author = {{Friesen, Olga and Meihost, Lars and Koch, Kevin and Claes, Leander and Henning, Bernd}},
location = {{Copenhagen}},
title = {{{Estimation of piezoelectric material parameters under varying electric field conditions}}},
doi = {{10.71568/DASDAGA2025.078}},
year = {{2025}},
}
@article{63250,
abstract = {{Abstract
An initial-boundary value problem for
$$\begin{aligned} \left\{ \begin{array}{ll}u_{tt} = \big (\gamma (\Theta ) u_{xt}\big )_x + au_{xx} - \big (f(\Theta )\big )_x, \qquad & x\in \Omega , \ t>0, \\[1mm] \Theta _t = \Theta _{xx} + \gamma (\Theta ) u_{xt}^2 - f(\Theta ) u_{xt}, \qquad & x\in \Omega , \ t>0, \end{array} \right. \end{aligned}$$
u
tt
=
(
γ
(
Θ
)
u
xt
)
x
+
a
u
xx
-
(
f
(
Θ
)
)
x
,
x
∈
Ω
,
t
>
0
,
[
1
m
m
]
Θ
t
=
Θ
xx
+
γ
(
Θ
)
u
xt
2
-
f
(
Θ
)
u
xt
,
x
∈
Ω
,
t
>
0
,
is considered in an open bounded real interval
$$\Omega $$
Ω
. Under the assumption that
$$\gamma \in C^0([0,\infty ))$$
γ
∈
C
0
(
[
0
,
∞
)
)
and
$$f\in C^0([0,\infty ))$$
f
∈
C
0
(
[
0
,
∞
)
)
are such that
$$f(0)=0$$
f
(
0
)
=
0
, and
$$k_\gamma \le \gamma \le K_\gamma $$
k
γ
≤
γ
≤
K
γ
as well as
$$\begin{aligned} |f(\xi )| \le K_f \cdot (\xi +1)^\alpha \qquad \hbox {for all } \xi \ge 0 \end{aligned}$$
|
f
(
ξ
)
|
≤
K
f
·
(
ξ
+
1
)
α
for all
ξ
≥
0
with some
$$k_\gamma>0, K_\gamma>0, K_f>0$$
k
γ
>
0
,
K
γ
>
0
,
K
f
>
0
and
$$\alpha <\frac{3}{2}$$
α
<
3
2
, for all suitably regular initial data of arbitrary size a statement on global existence of a global weak solution is derived. By particularly covering the thermodynamically consistent choice
$$f\equiv id$$
f
≡
i
d
of predominant physical relevance, this appears to go beyond previous related literature which seems to either rely on independence of
$$\gamma $$
γ
on
$$\Theta $$
Θ
, or to operate on finite time intervals.
}},
author = {{Winkler, Michael}},
issn = {{0044-2275}},
journal = {{Zeitschrift für angewandte Mathematik und Physik}},
number = {{5}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Large-data solutions in one-dimensional thermoviscoelasticity involving temperature-dependent viscosities}}},
doi = {{10.1007/s00033-025-02582-y}},
volume = {{76}},
year = {{2025}},
}
@article{63249,
abstract = {{Abstract
The model
$$\begin{aligned} \left\{ \begin{array}{l}u_{tt} = \big (\gamma (\Theta ) u_{xt}\big )_x + au_{xx} - \big (f(\Theta )\big )_x, \\[1mm] \Theta _t = \Theta _{xx} + \gamma (\Theta ) u_{xt}^2 - f(\Theta ) u_{xt}, \end{array} \right. \end{aligned}$$
u
tt
=
(
γ
(
Θ
)
u
xt
)
x
+
a
u
xx
-
(
f
(
Θ
)
)
x
,
[
1
m
m
]
Θ
t
=
Θ
xx
+
γ
(
Θ
)
u
xt
2
-
f
(
Θ
)
u
xt
,
for thermoviscoelastic evolution in one-dimensional Kelvin–Voigt materials is considered. By means of an approach based on maximal Sobolev regularity theory of scalar parabolic equations, it is shown that if
$$\gamma _0>0$$
γ
0
>
0
is fixed, then there exists
$$\delta =\delta (\gamma _0)>0$$
δ
=
δ
(
γ
0
)
>
0
with the property that for suitably regular initial data of arbitrary size an associated initial boundary value problem posed in an open bounded interval admits a global classical solution whenever
$$\gamma \in C^2([0,\infty ))$$
γ
∈
C
2
(
[
0
,
∞
)
)
and
$$f\in C^2([0,\infty ))$$
f
∈
C
2
(
[
0
,
∞
)
)
are such that
$$f(0)=0$$
f
(
0
)
=
0
and
$$|f(\xi )| \le K_f \cdot (\xi +1)^\alpha $$
|
f
(
ξ
)
|
≤
K
f
·
(
ξ
+
1
)
α
for all
$$\xi \ge 0$$
ξ
≥
0
and some
$$K_f>0$$
K
f
>
0
and
$$\alpha <\frac{3}{2}$$
α
<
3
2
, and that
$$\begin{aligned} \gamma _0 \le \gamma (\xi ) \le \gamma _0 + \delta \qquad \hbox {for all } \xi \ge 0. \end{aligned}$$
γ
0
≤
γ
(
ξ
)
≤
γ
0
+
δ
for all
ξ
≥
0
.
This is supplemented by a statement on global existence of certain strong solutions, particularly continuous in both components, under weaker conditions on the initial data.
}},
author = {{Winkler, Michael}},
issn = {{1424-3199}},
journal = {{Journal of Evolution Equations}},
number = {{4}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Large-data regular solutions in a one-dimensional thermoviscoelastic evolution problem involving temperature-dependent viscosities}}},
doi = {{10.1007/s00028-025-01144-z}},
volume = {{25}},
year = {{2025}},
}
@article{63246,
abstract = {{Abstract
The hyperbolic-parabolic model
$$\begin{aligned} \left\{ \begin{array}{ll} u_{tt} = u_{xx} - \big (f(\Theta )\big )_x, \qquad & x\in \Omega , \ t>0, \\ \Theta _t = \Theta _{xx} - f(\Theta ) u_{xt}, \qquad & x\in \Omega , \ t>0, \end{array} \right. \end{aligned}$$
u
tt
=
u
xx
-
(
f
(
Θ
)
)
x
,
x
∈
Ω
,
t
>
0
,
Θ
t
=
Θ
xx
-
f
(
Θ
)
u
xt
,
x
∈
Ω
,
t
>
0
,
for the evolution of the displacement variable
u
and the temperature
$$\Theta \ge 0$$
Θ
≥
0
during thermoelastic interaction in a one-dimensional bounded interval
$$\Omega $$
Ω
is considered. Whereas the literature has provided comprehensive results on global solutions for sufficiently regular initial data
$$(u_0,u_{0t},\Theta _0)=(u,u_t,\Theta )|_{t=0}$$
(
u
0
,
u
0
t
,
Θ
0
)
=
(
u
,
u
t
,
Θ
)
|
t
=
0
when
$$f\equiv id$$
f
≡
i
d
, it seems to have remained open so far how far a solution theory can be built solely on the two fundamental physical principles of energy conservation and entropy nondecrease. The present manuscript addresses this by asserting global existence of weak solutions under assumptions which are energy- and entropy-minimal in the sense of allowing for any initial data
$$u_0\in W_0^{1,2}(\Omega )$$
u
0
∈
W
0
1
,
2
(
Ω
)
,
$$u_{0t} \in L^2(\Omega )$$
u
0
t
∈
L
2
(
Ω
)
and
$$0\le \Theta _0\in L^1(\Omega )$$
0
≤
Θ
0
∈
L
1
(
Ω
)
, and which apply to arbitrary
$$f\in C^1([0,\infty ))$$
f
∈
C
1
(
[
0
,
∞
)
)
with
$$f(0)=0$$
f
(
0
)
=
0
and
$$f'>0$$
f
′
>
0
on
$$[0,\infty )$$
[
0
,
∞
)
.
}},
author = {{Winkler, Michael}},
issn = {{0944-2669}},
journal = {{Calculus of Variations and Partial Differential Equations}},
number = {{1}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Rough solutions in one-dimensional nonlinear thermoelasticity}}},
doi = {{10.1007/s00526-025-03170-8}},
volume = {{65}},
year = {{2025}},
}
@inproceedings{62297,
author = {{Hölscher, Jonas and Friesen, Olga and Claes, Leander and Spieker, Carsten and Förstner, Jens and Henning, Bernd}},
booktitle = {{2025 International Congress on Ultrasonics}},
keywords = {{tet_topic_piezo}},
pages = {{130–133}},
publisher = {{AMA Service GmbH}},
title = {{{Multiscale thermo-piezoelectric simulations using the finite element method}}},
doi = {{10.5162/ultrasonic2025/a18-a2}},
year = {{2025}},
}
@inproceedings{62296,
author = {{Spieker, Carsten and Förstner, Jens and Hölscher, Jonas and Claes, Leander and Henning, Bernd}},
booktitle = {{2025 International Congress on Ultrasonics}},
keywords = {{tet_topic_piezo}},
pages = {{126–129}},
publisher = {{AMA Service GmbH}},
title = {{{Modeling and simulation of the behavior of piezoceramics with the discontinuous Galerkin method}}},
doi = {{10.5162/ultrasonic2025/a18-a1}},
year = {{2025}},
}