diff --git a/source/user/manual/material/ndMaterial.rst b/source/user/manual/material/ndMaterial.rst
index 32fd14c7..9b92f723 100644
--- a/source/user/manual/material/ndMaterial.rst
+++ b/source/user/manual/material/ndMaterial.rst
@@ -27,6 +27,7 @@ The following contain information about matType? and the args required for each
 
    ndMaterials/ElasticIsotropic
    ndMaterials/ElasticOrthotropic
+   ndMaterials/TimberHoffman3D
    ndMaterials/J2Plasticity
    ndMaterials/DruckerPrager
    ndMaterials/ManzariDafalias
diff --git a/source/user/manual/material/ndMaterials/TimberHoffman3D.rst b/source/user/manual/material/ndMaterials/TimberHoffman3D.rst
new file mode 100644
index 00000000..2c63b707
--- /dev/null
+++ b/source/user/manual/material/ndMaterials/TimberHoffman3D.rst
@@ -0,0 +1,369 @@
+TimberHoffman3D Material
+========================
+
+This command is used to construct a nonlinear three-dimensional orthotropic timber material object based on the Hoffman failure criterion, isotropic hardening, and damage formulation.
+
+Tcl Version
+-----------
+
+.. code-block:: tcl
+
+   nDMaterial TimberHoffman3D $matTag $E1 $E2 $E3 $nu12 $nu13 $nu23 $G12 $G13 $G23 $fc1 $fc2 $fc3 $ft1 $ft2 $ft3 $f12 $f13 $f23 $h $Gf1t $Gf2t $Gf3t $eta
+
+Python Version
+--------------
+
+.. code-block:: python
+
+ops.nDMaterial('TimberHoffman3D', matTag, E1, E2, E3, nu12, nu13, nu23, G12, G13, G23, fc1, fc2, fc3, ft1, ft2, ft3, f12, f13, f23, h, Gf1t, Gf2t, Gf3t, eta)
+
++----------------------+-------------+------------------------------------+
+| **Argument**         | **Units /   | **Description**                    |
+|                      | type**      |                                    |
++======================+=============+====================================+
+| **matTag**           | integer     | Unique material tag.               |
++----------------------+-------------+------------------------------------+
+| **E1, E2, E3**       | Stress      | Young’s moduli in orthotropic      |
+|                      |             | material directions 1, 2, and 3.   |
++----------------------+-------------+------------------------------------+
+| **nu12, nu13, nu23** | —           | Independent Poisson ratios.        |
++----------------------+-------------+------------------------------------+
+| **G12, G13, G23**    | stress      | Shear moduli in planes 1–2, 1–3,   |
+|                      |             | and 2–3.                           |
++----------------------+-------------+------------------------------------+
+| **fc1, fc2, fc3**    | stress      | Compressive strengths in           |
+|                      |             | directions 1, 2, and 3.            |
++----------------------+-------------+------------------------------------+
+| **ft1, ft2, ft3**    | stress      | Tensile strengths in directions 1, |
+|                      |             | 2, and 3.                          |
++----------------------+-------------+------------------------------------+
+| **f12, f13, f23**    | stress      | Shear strengths in planes 1–2,     |
+|                      |             | 1–3, and 2–3.                      |
++----------------------+-------------+------------------------------------+
+| **h**                | stress      | Linear isotropic hardening         |
+|                      |             | modulus.                           |
++----------------------+-------------+------------------------------------+
+| **Gf1t, Gf2t, Gf3t** | energy/area | Tensile fracture energies in       |
+|                      |             | directions 1, 2, and 3.            |
++----------------------+-------------+------------------------------------+
+| **eta**              | —           | Viscous regularization parameter   |
+|                      |             | for damage evolution.              |
++----------------------+-------------+------------------------------------+
+
+**Theory:**
+
+1. **Orthotropic linear-elastic constitutive behavior:**
+
+In the elastic range the orthotropic material stress-strain relationship
+can be written in the form as:
+
+   |image1|
+
+   Where σ and ϵ are the applied stress and corresponding strain
+   tensors, respectively. E is the orthogonal elastic matrix which is
+   given as:
+
+|image2|
+
+Where *E\ i* represents the young’s moduli in the three orthotropic
+directions, υ\ :sub:`ij` and G\ :sub:`ij` are the Poisson’s ratio and
+shear moduli, respectively. Direction 1 is the direction parallel to
+grain (longitudinal) and directions 2 and 3 are the radial and
+tangential directions.
+
+2. **Elastoplastic constitutive behavior:**
+
+A constitutive relationship is adopted for timber material based on the
+isotropic hardening elastoplastic model using the Hoffman yield
+criterion, which is an extension of Hill’s criterion. **Hoffman yield
+function** along with the yield criterion combined with isotropic
+hardening is formulated as:
+
+   |image3|
+
+|image4|
+
+|image5|
+
+Where; **P** and **Q** are mapping matrices with the variables as stated
+in above formulas in which the **σ\ e** is the equivalent yield stress
+and **σ\ ek** is the formulation stated as below:
+
+|image6|
+
+In which the h is the hardening modulus and k is the hardening variable.
+“\ *k*\ ” depends on the equivalent plastic strain obtained by means
+iterative method (Newton-Raphson) for each load increment. However, “h”
+is an input parameter of the proposed model which can be directly
+obtained from the uniaxial stress–strain diagram. Depending on the
+chosen value of h, perfect plasticity, slight hardening or softening can
+be modelled. “h” parameter can simply be computed from:
+
+|image7|
+
+In which the **T\ 2** is the plastic tangent modulus in the orthotropic
+2 direction. In the hardening state, each yield value will change
+depending on the corresponding hardening parameter ki (i =1,2,..,9).
+Thus, the parameters in the mapping vector Q change also. Isotropic
+hardening is considered in this paper, because it assumes that the
+initial yield surface expands uniformly without translation and
+distortion as plasticity occurs. Thus, all the yield values change in
+the same order. Consequently, the parameters α11, α22 and α33 in the
+mapping vector Q will change depending on the hardening parameter k.
+
+|image8|
+
+If the stress reaches the yield condition, the elastoplastic radial
+mapping algorithm is used to constrain stress point on the yield
+surface. According to the theory of plasticity, the total strain
+increment *Δε* can be divided into elastic component *Δε\ e* and plastic
+component *Δε\ p* as:
+
+|image9|
+
+Where the associated flow rule was used to determine the plastic strain
+as:
+
+|image10|
+
+In which Δλ denotes the plastic multiplier and ∂f ∂σ is the gradient
+vector of the plastic potential energy function of f(σ,k) which can be
+written as:
+
+|image11|
+
+3. **Damage Evolution:**
+
+Anisotropic damage with non-uniform distribution of micro cracks and
+voids in all directions of the timber matrix is considered. To consider
+the anisotropic damage, three different damage factors must be
+introduced. The reduction of the elastic stiffness matrix is simulated
+here as a function of damage evolution in three orthogonal directions.
+Therefore, the damaged stiffness matrix with the damage factors can be
+written as:
+
+|image12|
+
+where d1, d2 and d3 are the damage factors defined in the longitudinal,
+radial and tangential directions, respectively. The damage factor, di (i
+=1,2,3), increases from 0 to 1 as damage grows from threshold value to
+its ultimate value.
+
+Since the timber has different damage evolution for tensile and
+compression failures, the damage models are used to define the tensile
+and compression damage evolutions. In this study, different tensile
+damages in three orthogonal directions and compressive damage in only
+longitudinal direction are considered as:
+
+|image13|
+
+In which dit, and Gfit are the tensile damage factor and fracture energy
+under tension in the i-th direction of the timber, respectively. d1c is
+the compression damage factor in the longitudinal direction of the
+timber. Lc is the element characteristic length. Fit and F1c are the
+variables and “A” and “B” are the material constants.
+
+The stress-based continuum damage formulation with different failure
+criteria in tension and compression is used in this study. It means,
+damage starts to accumulate as soon as the stresses satisfy the failure
+criterion. The failure criterion is described as:
+
+|image14|
+
+|image15|
+
+Damage models can encounter convergence problems in static analysis. To
+improve the convergence, viscous regularisation method is used to define
+the model. In the viscous regularisation, the response of damaged
+material is evaluated using a viscous regularised damage variable dv
+which is defined as:
+
+|image16|
+
+where η is the viscous parameter. A small value of the viscous parameter
+usually helps to improve the convergence rate of the model without
+significantly influencing the results. Thus, the value of viscous
+parameter is chosen to be equal to 0.0001.
+
+**Responses/Backbones:**
+
+**Example:
+**
+
++-----------------+----------------+-----------------+----------------+
+| **Property**    | **Value**      | **Property**    | **Value**      |
++=================+================+=================+================+
+| **E1**          | 2050.8         | **E2=E3**       | 172.1          |
++-----------------+----------------+-----------------+----------------+
+| **G23**         | 68             | **G12=G13**     | 145.2          |
++-----------------+----------------+-----------------+----------------+
+| **ν23**         | 0.5            | **ν12=ν13**     | 0.45           |
++-----------------+----------------+-----------------+----------------+
+| **fc1**         | 35             | **fc2=fc3**     | 2.5            |
++-----------------+----------------+-----------------+----------------+
+| **ft1**         | 20             | **ft2=ft3**     | 0.7            |
++-----------------+----------------+-----------------+----------------+
+| **f23**         | 0.5            | **f12=f13**     | 5              |
++-----------------+----------------+-----------------+----------------+
+| **h**           | 1200           | **Gf1t**        | 60             |
++-----------------+----------------+-----------------+----------------+
+| **Gf2t=Gf3t**   | 0.5            | **η**           | 0.0001         |
++-----------------+----------------+-----------------+----------------+
+
+**Without the Q evolution:**
+
+|image17|
+
+**With the Q evolution:**
+
+**Effect of damage and hardening on cyclic response.** The
+perpendicular-to-grain cyclic response exhibited progressively narrower
+hysteresis loops following the onset of damage. This behavior reflects
+the combined effects of stiffness degradation and isotropic hardening in
+the constitutive formulation. As damage accumulated, the effective
+stiffness decreased substantially, resulting in reduced nominal stress
+during subsequent loading cycles. Concurrently, evolution of the Hoffman
+yield surface through the hardening variable Q(k) allowed a larger
+portion of the unloading and reloading path to remain within the
+expanded yield surface, thereby limiting additional plastic deformation
+and associated hysteretic dissipation. Consequently, the combination of
+damage-induced stiffness degradation and reduced repeated plastic
+yielding produced thinner cyclic loops compared with the response
+obtained using the initial, non-evolving Q0. In the perpendicular
+specimen, this effect was particularly pronounced after localized damage
+approached unity, while the volume-averaged damage remained
+approximately 0.5, indicating a strongly nonuniform damage state.
+
+|image18|
+
+|image19|
+
+**Multi-Axial Tests:**
+
+**Combined compression–shear response.** The constitutive response under
+combined longitudinal compression and 1-2 shear was examined using a
+prescribed non-monotonic strain path involving shear reversal. During
+the initial loading stage, the equivalent plastic strain (k) increased
+together with the isotropic hardening variables Qi(k), while
+longitudinal damage (d1) progressively developed. During subsequent
+shear reversal, the normalized Hoffman yield function became negative,
+and both k and Qi(k) remained approximately constant, indicating elastic
+unloading/reloading within the expanded yield surface. Continued reverse
+loading brought the effective stress state back to the yield surface,
+producing a second increase in equivalent plastic strain and hardening.
+The accumulated directional damage remained irreversible throughout the
+reversal, with substantial damage developing only in the longitudinal
+direction. Overall, the response demonstrates the interaction of Hoffman
+plasticity, isotropic hardening, directional damage, and loading-path
+dependence under combined normal and shear deformation. The results are
+interpreted as constitutive material-point diagnostics rather than
+specimen-level or experimental validation.
+
+|image20|
+
+**Transverse compression–shear response.** The constitutive response
+under combined transverse compression and 2-3 shear was examined using a
+non-monotonic loading path involving shear reversal. During the initial
+loading stage, the equivalent plastic strain (k) increased together with
+the isotropic hardening variables Qi(k), indicating activation of the
+Hoffman plasticity model and expansion of the yield surface. During
+subsequent shear reversal, the normalized Hoffman yield function became
+negative, while k and Qi(k) remained approximately constant, indicating
+elastic unloading/reloading within the expanded yield surface. Continued
+reverse loading brought the effective stress state back to the yield
+surface, resulting in a second increase in equivalent plastic strain and
+isotropic hardening. In contrast to the longitudinal compression and 1-2
+shear case, no appreciable directional damage developed during this
+loading history, demonstrating that plastic yielding and damage
+initiation remain distinct mechanisms within the constitutive
+formulation. Overall, the response demonstrates the interaction of
+anisotropic Hoffman plasticity, isotropic hardening, and loading-path
+reversal under combined transverse compression and shear. The results
+are interpreted as constitutive material-point diagnostics rather than
+specimen-level or experimental validation.\ |image21| **Biaxial
+compression response.** The constitutive response under biaxial
+compression was examined by simultaneously prescribing compressive
+strains in the longitudinal and transverse material directions, followed
+by unloading. During the loading stage, plastic yielding resulted in an
+increase in the equivalent plastic strain (k) together with the
+isotropic hardening variables Qi(k), indicating progressive expansion of
+the Hoffman yield surface. Directional damage developed predominantly in
+the longitudinal direction, with d1 increasing substantially while d2
+and d3 remained negligible over most of the loading history. During
+unloading, the normalized Hoffman yield function became negative and
+moved into the interior of the evolved yield surface, while k and Qi(k)
+remained approximately constant, indicating that no significant
+additional plastic evolution occurred. The resulting nonlinear and
+path-dependent stress response reflects the combined effects of
+multiaxial Hoffman plasticity, isotropic hardening, and directional
+damage. The results are interpreted as constitutive material-point
+diagnostics rather than specimen-level or experimental validation.
+
+|image22|
+
+.. |image1| image:: media/image1.png
+   :width: 0.83341in
+   :height: 0.29169in
+.. |image2| image:: media/image2.png
+   :width: 6.5in
+   :height: 2.87083in
+.. |image3| image:: media/image3.png
+   :width: 2.87525in
+   :height: 0.58338in
+.. |image4| image:: media/image4.png
+   :width: 4.95876in
+   :height: 1.47513in
+.. |image5| image:: media/image5.png
+   :width: 4.00833in
+   :height: 5.56876in
+.. |image6| image:: media/image6.png
+   :width: 1.56712in
+   :height: 0.40833in
+.. |image7| image:: media/image7.png
+   :width: 1.42417in
+   :height: 0.57222in
+.. |image8| image:: media/image8.png
+   :width: 2.26686in
+   :height: 0.66672in
+.. |image9| image:: media/image9.png
+   :width: 1.20844in
+   :height: 0.37503in
+.. |image10| image:: media/image10.png
+   :width: 1.35012in
+   :height: 0.58338in
+.. |image11| image:: media/image11.png
+   :width: 3.892in
+   :height: 1.40012in
+.. |image12| image:: media/image12.png
+   :width: 6.68094in
+   :height: 1in
+.. |image13| image:: media/image13.png
+   :width: 3.06693in
+   :height: 1.34178in
+.. |image14| image:: media/image14.png
+   :width: 2.08351in
+   :height: 0.59172in
+.. |image15| image:: media/image15.png
+   :width: 3.71699in
+   :height: 1.64181in
+.. |image16| image:: media/image16.png
+   :width: 1.18344in
+   :height: 0.46671in
+.. |image17| image:: media/image17.png
+   :width: 9.12222in
+   :height: 4.77778in
+.. |image18| image:: media/image18.png
+   :width: 5.45238in
+   :height: 6.23121in
+.. |image19| image:: media/image19.png
+   :width: 5.56257in
+   :height: 6.35714in
+.. |image20| image:: media/image20.png
+   :width: 8.24306in
+   :height: 4.71032in
+.. |image21| image:: media/image21.png
+   :width: 8.45766in
+   :height: 4.83333in
+.. |image22| image:: media/image22.png
+   :width: 8.17949in
+   :height: 4.67437in
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