Physics-Informed Framework for Impact Identification in Aerospace Composites
Authors: Natália Ribeiro Marinho, Richard Loendersloot, Jan Willem Wiegman, Frank Grooteman, Tiedo Tinga
Organizations: Engineering Technology Faculty, Department of Mechanics of Solids, Surfaces and Systems, Dynamics Based Maintenance (DBM) Group, University of Twente (UT), Enschede, NL · Department of Aerospace Vehicles Integrity and Life Cycle Support (AVIL), Royal Netherlands Aerospace Centre (NLR), Marknesse, NL
This paper introduces a novel physics-informed impact identification (Phy-ID) framework. The proposed method integrates observational, inductive, and learning biases to combine physical knowledge with data-driven inference in a unified modelling strategy, achieving physically consistent and numerically stable impact identification. The physics-informed approach structures the input space using physics-based energy indicators, constrains admissible solutions via architectural design, and enforces governing relations via hybrid loss formulations. Together, these mechanisms limit non-physical solutions and stabilise inference under degraded measurement conditions. A disjoint inference formulation is used as a representative use case to demonstrate the framework capabilities, in which impact velocity and impactor mass are inferred through decoupled surrogate models, and impact energy is computed by enforcing kinetic energy consistency. Experimental evaluations show mean absolute percentage errors below 8% for inferred impact velocity and impactor mass and below 10% for impact energy. Additional analyses confirm stable performance under reduced data availability and increased measurement noise, as well as generalisation for out-of-distribution cases across pristine and damaged regimes when damaged responses are included in training. These results indicate that the systematic integration of physics-informed biases enables reliable, physically consistent, and data-efficient impact identification, highlighting the potential of the approach for practical monitoring systems.
Figures & tables
Figure 1: General framework of Physics-Informed Impact Identification (Phy-ID), showing how observational, inductive, and learning biases are combined in a structured integration step to achieve physics-informed impact energy estimation.
Figure 2: High-level overview of the sequential disjoint training process: the displacement network (top) generates a velocity estimate for the impactor mass network (bottom), which in turn produces a mass estimate fed back to the displacement model.
Parameter
Displacement network, wθ(x,t)
Mass network, mϕ(x)
fully connected layer size, nh
32, 64, 128, 256
16, 32, 64
number of hidden layers, Lh
2, 3, 4
2, 3
learning rate, lr
10−2 , 10−3
10−2 , 10−3
activation function
Sigmoid, Softplus, Tanh
Sigmoid, Softplus, Tanh
Table 1: Hyperparameter search space explored for the displacement and mass FCNNs.
Parameter
Value
Displacement network wθ(x,t)
architecture
FCNN, 3 hidden layers of size 256, activation tanh
output
impact velocity, v^0
learning rate
1×10−2
loss function
Ldisp=λv0Lv0+λicLIC+λkeLKE
weighting factors
λv0=1×10−4 , λIC=1×10−6 and λKE=1×10−4
Table 2: Implementation settings for the disjoint PINN architecture.
Figure 3: Parallel coordinate plots showing the performance of the displacement and mass networks across hyperparameter combinations. ( nh : fully connected layer size; Lh : number of fully connected layers; lr : learning rate; and σ : activation functions.)
Figure 4: Schematic impact test configuration; ∙ piezoelectric sensors (PZT) and ⋆ Impact Locations (IE): (a) drop-tower assembly with impact height ( h ) set by impact energy; (b) stiffened thermoplastic composite structure ( 1600×370 mm) with varying thicknesses t1=8.26 mm, t2=6.30 mm, and t3=5.46 mm; (c) experimental set-up, with stiffeners at the bottom-side of the panel. Adapted from ( Marinho et al., 2025b ; Marinho et al., 2024 ) .
ID
Coordinates [mm]
x
y
PZT1
255
428
PZT2
252
818
PZT3
250
945
PZT4
187
945
PZT5
125
945
Table 3: Impact locations and sensor network coordinates.
Number of unique targets
73
Minimum energy [J]
3.74
Maximum energy [J]
80.95
Mean energy [J]
35.92
Median energy [J]
29.83
Standard deviation [J]
24.04
Table 4: Impact energy statistics.
Figure 5: Phased array ultrasonic scans for different impact locations acquired after the impact events that precede and produce damage, highlighting the impact energy associated with damage onset. Each scan shows backwall attenuation, reflection view and cross-sectional view.
Case a,b
Description
Impact data
Training scenario
Samples
Data avail. [%]
Noise [%]
Energy range c [J]
P1
Predictive analytics
100
1.0
4–80
146
R1
Data availability sweep
25–100
0.0
4–80
variable
R2
Noise sweep
100
0–5
4–80
73
R3
Combined availability and noise
25–100
0–5
4–80
variable
G1
Out-of-distribution training ranges
100
1.0
variable
146
Table 5: Summary of data processing cases for predictive analytics, robustness analysis and generalisation assessment.
Figure 6: Data-processing workflow highlighting the associated analysis cases: P1 (predictive analytics), R1 (data availability sweep), R2 (noise sweep), R3 (combined availability and noise), and G1 (out-of-distribution training ranges).
Figure 7: Comparison between the original and noisy signals recorded by PZT5 due to an impact event of 10 J at impact location IE1. PZT: piezoelectric
Domain
Group
ID
wm
rm
sm
evaluation
Time
T1
RMS
0.58
0.97
0.57
∗∗ / ∙∙
T2
TE
0.59
0.95
0.56
∗∗ / ∙∙
T3
PA
0.61
0.99
0.60
∗∗ / ∙∙
T4
EPR
0.61
0.95
0.58
∗∗ / ∙∙
T5
RA
0.34
0.80
0.28
∗∗ / ⋄
Frequency
F1
PCR
0.34
0.81
0.28
∗∗ / ∙∙
Table 6: Feature ranking and selection for defining the physics-based energy indicators.
Figure 8: Predictive analytics results for Case P1. MAPE: Mean Absolute Percentage Error
Figure 9: Impact energy inferred after removing architectural priors, surrogate components, and hybrid loss terms.
Figure 10: Impact energy robustness analysis. Measured error across energy bins for (left) varying data availability at zero noise (Case R1), (centre) increasing noise levels at full data availability (Case R2), and (right) combined reductions in data availability and increases in noise (Case R3). MAPE: Mean Absolute Percentage Error
Figure 11: Generalisation behaviour for varying training intervals. Predictions are evaluated on Out-Of-Distribution (OOD) samples outside each training range, illustrating extrapolation in impact energy estimation.
Figure 12: Generalisation behaviour without physics-motivated architectural priors, surrogate components, and hybrid loss terms. Predictions on out-of-distribution samples illustrate extrapolation in impact energy estimation.
Criterion
Data-driven
Physics-based
Probabilistic
Physics-informed (Phy-ID)
Accuracy
Low–Medium ( Malekloo et al., 2021 ; Azimi et al., 2020 ; Jia and Li, 2023 )
Low–Medium ( Kralovec and Schagerl, 2020 ; Fan et al., 2021 )
Medium ( Blakseth et al., 2022 ; Arias Chao et al., 2022 )
High
Robustness
Low ( Azimi et al., 2020 ; Nicassio et al., 2025 )
Low–Medium ( Fan et al., 2021 ; Hassani et al., 2021 )
Medium ( Blakseth et al., 2022 ; Arias Chao et al., 2022 )
High
Generalisation
Low ( Azimi et al., 2020 ; Nicassio et al., 2025 )
Low–Medium ( Fan et al., 2021 ; Malekloo et al., 2021 )
Medium ( Blakseth et al., 2022 ; Arias Chao et al., 2022 )
Medium
Interpretability
Low ( Azimi et al., 2020 ; Nicassio et al., 2025 )
High ( Fan et al., 2021 ; Malekloo et al., 2021 )
Low–Medium ( Blakseth et al., 2022 ; Arias Chao et al., 2022 )
High
Table 7: Qualitative comparison of impact identification strategies under limited and noisy data with incomplete physics.
∗The MathWorks Inc., 1 Apple Hill Drive, Natick, MA 01760 USA · ∗∗ECE Dept., Northeastern University, Boston, MA 02115, USA · ∗∗∗Div. of Automatic Control, Linköping University, Sweden